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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

x      QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2011

or

o         TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                      to                     

Commission File Number 001-33291

OPTIMER PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

10110 Sorrento Valley Road, Suite C
San Diego, CA 92121
(Address of principal executive offices, including zip code)

(858) 909-0736
(Registrant’s telephone number, including area code)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days:  Yes x  No o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files):  Yes x  No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See the definitions of “large accelerated filer”, “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act:

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act):  Yes o  No x

The number of shares of the registrant’s common stock, par value $0.001 per share, outstanding as of October 31, 2011 was 46,645,252 shares.

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OPTIMER PHARMACEUTICALS, INC.
FORM 10-Q
For the Quarterly Period Ended September 30, 2011

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PART I — FINANCIAL INFORMATION

Item 1.  Financial Statements

Optimer Pharmaceuticals, Inc.

Consolidated Balance Sheets

See accompanying notes.

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Optimer Pharmaceuticals, Inc.

Consolidated Statements of Operations

(unaudited)

See accompanying notes.

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Optimer Pharmaceuticals, Inc.

Consolidated Statements of Cash Flows

(unaudited)

See accompanying notes.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements

(unaudited)

1.              Interim Financial Information

Organization and Business Activities

Optimer Pharmaceuticals, Inc. (“Optimer” or the “Company”) was incorporated in Delaware on November 18, 1998. The Company has a majority-owned subsidiary, Optimer Biotechnology, Inc. (“OBI”), which is incorporated and located in Taiwan. In October 2009, Optimer sold 40% of its equity interest in OBI. Prior to the sale, OBI was a wholly owned subsidiary of Optimer.  Optimer also recently established a wholly-owned subsidiary, Optimer Pharmaceuticals Canada, Inc., which is incorporated and located in Canada.

Optimer is a biopharmaceutical company focused on discovering, developing and commercializing innovative hospital specialty products.  The Company currently has one anti-infective product, DIFICID™ (fidaxomicin), which is approved in the United States for the treatment of Clostridium difficile-associated diarrhea (“CDAD”) and is developing additional product candidates using its proprietary technology, including its OPopS™ drug discovery platform.

Basis of Presentation

The accompanying unaudited consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring accruals, considered necessary for a fair presentation of the results of these interim periods have been included. The results of operations for the three months and nine months ended September 30, 2011 are not necessarily indicative of the results that may be expected for the full year. These unaudited consolidated financial statements should be read in conjunction with the audited financial statements and related notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2010, which was filed with the Securities and Exchange Commission (“SEC”) on March 10, 2011.

The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates.

2.              Summary of Significant Accounting Policies

Cash, Cash Equivalents and Investments

Investments with original maturities of less than 90 days at the date of purchase are considered to be cash equivalents.  Except for one auction rate preferred security (“ARPS”), all other investments are classified as short-term investments which are deemed by management to be available-for-sale and are reported at fair value with net unrealized gains or losses reported

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

within other comprehensive loss in the consolidated statement of stockholders’ equity.  Realized gains and losses, and declines in value judged to be other than temporary, are included in investment income or interest expense.  The cost of securities sold is computed using the specific identification method.

Inventory

Inventory is stated at the lower of cost or market.  Cost is determined in a manner which approximates the first-in, first-out (“FIFO”) method. The Company capitalizes inventory produced in preparation for product launches upon FDA approval when costs are expected to be recoverable through the commercialization of the product.  The Company reserves for potentially excess, dated or obsolete inventories based on an analysis of inventory on hand compared to forecasts of future sales. As of September 30, 2011, inventories consist of $954,455 in raw materials, $479,975 in work in progress and $810,732 in finished goods.

Reclassifications

The Company has reclassified certain prior period amounts to conform to the current period presentation.  Specifically, it has consolidated its sales and marketing expense and its general and administrative expense into a single selling, general and administrative expense category.  This reclassification has no impact on the net loss from operations or stockholder’s equity as previously reported.

Revenue Recognition

DIFICID is available through three major wholesalers, AmerisourceBergen Corporation, Cardinal Health, Inc., and McKesson Corporation, and regional wholesalers that provide the DIFICID to hospital and retail pharmacies, and long-term care facilities. The Company applies the revenue recognition guidance in Staff Accounting Bulletin (“SAB”) 104 and does not recognize revenue from product sales until there is persuasive evidence of an arrangement, delivery has occurred, title has passed to the customer, the price is fixed and determinable, the buyer is obligated to pay the Company, the obligation to pay is not contingent on resale of the product, the buyer has economic substance apart from the Company, the Company has no obligation to bring about the sale of the product, the amount of returns can be reasonably estimated and collectability is reasonably assured. The Company recognizes product sales of DIFICID upon delivery of product to the wholesalers.

The Company’s net product revenues represent total product revenues less allowances for customer credits, including estimated rebates, discounts and returns. These allowances are established by management as its best estimate based on available information and will be adjusted to reflect

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

known changes in the factors that impact such allowances. Allowances for rebates, discounts and returns are established based on the contractual terms with customers, communications with customers as well as expectations about the market for the product and anticipated introduction of competitive products.  Product shipping and handling costs are included in cost of sales.

Product Sales Allowances.  The Company establishes reserves for prompt payment discounts, government rebates, product returns and other applicable allowances.  Reserves established for these discounts and allowances are classified as a reduction of accounts receivable.

Allowances against receivable balances primarily relate to prompt payment discounts and fee for service arrangements with our contracted wholesalers and are recorded at the time of sale, resulting in a reduction in product sales revenue.  Accruals related to government rebates, product returns and other applicable allowances are recognized at the time of sale, resulting in a reduction in product sales revenue and the recording of an increase in accrued expenses.

Prompt Payment Discounts.  The Company offers a prompt payment discount to its contracted wholesalers.  Since the Company expects its customers will take advantage of this discount, the Company accrues 100% of the prompt payment discount that is based on the gross amount of each invoice, at the time of sale.  The accrual is adjusted quarterly to reflect actual earned discounts.

Government Rebates and Chargebacks.  The Company estimates government mandated rebates and discounts relating to federal and state programs such as Medicaid, Veterans’ Administration (“VA”) and Department of Defense programs, the Medicare Part D Coverage Discount Program, as well as certain other qualifying federal and state government programs.  The Company estimates the amount of these reductions based on DIFICID patient data, actual sales data and market research data related to payor mix.  These allowances are adjusted each period based on actual experience.

Medicaid rebate reserves relate to the Company’s estimated obligations to states under statutory “best price” obligations which may also include supplemental rebate agreements with certain states.  Rebate accruals are recorded during the same period in which the related product sales are recognized.  Actual rebate amounts are determined at the time of claim by the state, and the Company will generally make cash payments for such amounts after receiving billings from the state.

VA rebates or chargeback reserves represent the Company’s estimated obligations resulting from contractual commitments to sell DIFICID to qualified healthcare providers at a price lower than the list price charged to the Company’s distributor.  The distributor will charge the Company for the difference between what the distributor pays for the product and the ultimate selling price to the qualified healthcare provider.  Rebate accruals are established during the same period in which the related product sales are recognized. Actual chargeback amounts for Public Health Service are determined at the time of resale to the qualified healthcare provider from the distributor, and the Company will generally issue credits for such amounts after receiving notification from the distributor.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

Although allowances and accruals are recorded at the time of product sale, certain rebates will generally be paid out, on average, up to six months or longer after the sale.  Reserve estimates are evaluated quarterly and, if necessary, adjusted to reflect actual results.  Any such adjustments will be reflected in the Company’s operating results in the period of the adjustment.

Product Returns.  The Company’s policy is to accept returns of DIFICID for six months prior to and twelve months after the product expiration date.  The Company also permits returns if the product is damaged or defective when received by its customers. The Company will provide a credit for such returns to customers with whom the Company has a direct relationship. Once product is dispensed, it cannot be returned, but the Company allows partial returns in states where such returns are mandated. The Company does not exchange product from inventory for the returned product.

Allowances for product returns are recorded during the period in which the related product sales are recognized, resulting in a reduction to product revenue.  The Company estimates product returns based upon historical trends in the pharmaceutical industry and trends for similar products sold by others.

Collaborations, Milestones and Royalties

In order to determine the revenue recognition for contingent milestones, the Company evaluates the contingent milestones using the criteria as provided by the Financial Accounting Standards Boards (“FASB”) guidance on the milestone method of revenue recognition at the inception of a collaboration agreement.

Accounting Standard Codification (“ASC”) Topic 605-28, Revenue Recognition — Milestone Method (“ASC 605-28”), established the milestone method as an acceptable method of revenue recognition for certain contingent event-based payments under research and development arrangements.  Under the milestone method, a payment that is contingent upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved.  A milestone is an event (i) that can be achieved based in whole or in part on either the Company’s performance or on the occurrence of a specific outcome resulting from the Company’s performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved, and (iii) that would result in additional payments being due to the Company.  The determination that a milestone is substantive is judgmental and is made at the inception of the arrangement.  Milestones are considered substantive when the consideration earned from the achievement of the milestone is (i) commensurate with either the Company’s performance to achieve the milestone or the enhancement of value of the item delivered as a result of a specific outcome resulting from the Company’s performance to achieve the milestone, (ii) relates solely to past performance and (iii) is reasonable relative to all deliverables and payment terms in the arrangement.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

Other contingent event-based payments received for which payment is either contingent solely upon the passage of time or the results of a collaborative partner’s performance are not considered milestones under ASC 605-28.  In accordance with ASC Topic 605-25, Revenue Recognition — Multiple-Element Arrangements, such payments will be recognized as revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; price is fixed or determinable; and collectability is reasonably assured.

Revenues recognized for royalty payments, if any, are recognized as earned in accordance with the terms of various research and collaboration agreements.

For collaboration agreements with multiple deliverables, the Company recognizes collaboration revenues and expenses by analyzing each element of the agreement to determine if it is to be accounted for as a separate element or single unit of accounting. If an element is to be treated separately for revenue recognition purposes, the revenue recognition principles most appropriate for that element are applied to determine when revenue is to be recognized. If an element is not to be treated separately for revenue recognition purposes, the revenue recognition principles most appropriate for the bundled group of elements are applied to determine when revenue is to be recognized.

Cash received in advance of services being performed is recorded as deferred revenue and recognized as revenue as services are performed over the applicable term of the agreement.

In connection with certain research collaboration agreements, revenues are recognized from non-refundable upfront fees, which the Company does not believe are specifically tied to a separate earnings process, ratably over the term of the agreement.  Research fees are recognized as revenue as the related research activities are performed.

With respect to revenues derived from reimbursement of direct out-of-pocket expenses for research costs associated with grants, where the Company acts as a principal, with discretion to choose suppliers, bears credit risk and performs part of the services required in the transaction, the Company records revenue for the gross amount of the reimbursement. The costs associated with these reimbursements are reflected as a component of research and development expense in the consolidated statements of operations.

In February 2011, the Company entered into a collaboration and license agreement with Astellas Pharma Europe Ltd. (“Astellas”).  Under the terms of the license agreement with Astellas, Astellas paid the Company an upfront fee of $69.2 million.  The Company is also eligible to receive additional payments under the collaboration and license agreement upon the achievement of specified regulatory and commercial milestones and contingent events.  The Company has assessed the revenue recognition method for the achievement of the milestones at the inception of the arrangement using the milestone method.

None of the payments that the Company has received from collaborators to date, whether recognized as revenue or deferred, are refundable even if the related program is not successful.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

Research and Development Expenses

The Company expenses costs related to research and development until technological feasibility has been established for the product.  Once technological feasibility is established, all product costs are generally capitalized until the product is available for general release to customers.  The Company has determined that technological feasibility for its product candidates will be reached when the requisite regulatory approvals are obtained to make the product available for sale, which, in the United States, generally occurs upon the approval of the New Drug Application (“NDA”) for such product.  In November 2010, the Company paid a $1.5 million filing fee to the FDA associated with the NDA for DIFICID.  The filing fee is potentially refundable for companies that qualify as a small business which is defined by the Small Business Association (“SBA”) as a company with 250 employees or less.  The Company asserted that it qualifies as a small business and submitted data to the SBA to support its assertion.  As the small business determination was uncertain, the Company recorded the $1.5 million NDA fee as research and development expense.  In March 2011, the Company received a letter from the SBA concurring with the Company’s assessment that it was a small business. Consequently, the Company recorded the $1.5 million fee as a receivable and reduced the research and development expenses in March 2011. In June 2011, the Company was refunded the $1.5 million fee from the SBA.

The Company’s research and development expenses consist primarily of license fees, salaries and related employee benefits, costs associated with clinical trials managed by the Company’s contract research organizations and costs associated with non-clinical activities and regulatory approvals.  The Company uses external service providers and vendors to conduct clinical trials, to manufacture supplies of product candidates to be used in clinical trials and to provide various other research and development-related products and services.

When nonrefundable payments for goods or services to be received in the future for use in research and development activities are made, the Company defers and capitalizes these types of payments. The capitalized amounts are expensed when the related goods are delivered or the services are performed.

Comprehensive Income (Loss)

Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources.  Net income (loss) and other comprehensive income (loss), including foreign currency translation adjustments and unrealized gains and losses on investments, is required to be reported, net of their related tax effect, to arrive at comprehensive income (loss).  Consolidated comprehensive loss was ($28.0) million and ($12.3) million for the three months ended September 30, 2011 and 2010, respectively. Consolidated comprehensive loss was ($7.5) million and ($36.2) million for the nine months ended September 30, 2011 and 2010, respectively.  As of September 30, 2011, the cumulative unrealized loss on investments and the cumulative loss on foreign currency translation adjustment was ($133,176) and ($119,432), respectively. As of December 31, 2010, the cumulative unrealized loss on investments and the cumulative gain on foreign currency translation adjustment was $3,020 and $301,870, respectively.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

Net Income (Loss) Per Share Attributable to Common Stockholders

Basic net income (loss) per common share is computed by dividing net loss by the weighted-average number of common shares outstanding. Diluted net income (loss) per common share is computed by dividing net loss by the weighted-average number of common shares and dilutive common share equivalents then outstanding. Common equivalent shares consist of common shares issuable upon the exercise of stock options and warrants.

Income Taxes

Income taxes are accounted for under the asset and liability method.  Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards.  Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.  The effect on deferred tax assets and liabilities of a change in tax rates is recognized as income in the period that includes the enactment date.  The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized.

Recently Issued Accounting Pronouncements

In May 2011, the FASB issued an update to existing guidance on fair value measurement and disclosure requirements under U.S. GAAP and International Financial Reporting Standards.  The amendments in this update change the wording used to describe many of the requirements under U.S. GAAP for measuring fair value and for disclosing information about fair value measurements. The amendments in this update will be effective for interim and annual periods beginning after December 15, 2011 and should be applied retrospectively. The adoption of these amendments is not expected to have a material impact on the Company’s financial position, cash flow or results of operations.

In June 2011, the FASB issued an update which amends the presentation of comprehensive income. The objective of this update is to improve the comparability, consistency, and transparency of financial reporting and to increase the prominence of items reported in other comprehensive income.  Under this update, an entity has the option to present the total of comprehensive income, the components of net income and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. Under either choice, an entity is required to present each component of net income along with total net income, each component of other comprehensive income along with a total for other comprehensive income, and a total amount for comprehensive income. The amendments in this update will be effective for fiscal years, and interim periods within those years, beginning after December 15, 2011 and should be applied prospectively. The adoption of these amendments is not expected to have a material impact on the Company’s financial position, cash flow or results of operations.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

3.   Fair Value of Financial Instruments

The following table summarizes the Company’s financial assets measured at fair value on a recurring basis subject to the disclosure requirements as of September 30, 2011:

Level 1:  Quoted prices in active markets for identical assets and liabilities; or

Level 2:  Quoted prices for identical or similar assets and liabilities in markets that are not active, or observable inputs other than quoted prices in active markets for identical assets and liabilities; or

Level 3:  Unobservable inputs.

A reconciliation of the beginning and ending balances of assets measured at fair value on a recurring basis using Level 3 inputs is as follows:

All of the Company’s investments in available-for-sale securities are recorded at fair value based on quoted market prices. As of September 30, 2011, the Company held one ARPS valued at $882,000 with a perpetual maturity date that resets every 28 days.  Although as of September 30, 2011, this ARPS continued to pay interest according to its stated terms, the market in these securities continues to be illiquid. Based on a discounted cash flow model used to determine the estimated fair value of its investment in the ARPS, the Company has previously recognized in the consolidated statement of operations an unrealized loss of approximately $118,000 in investment income since the Company had determined that the decline in value was other than temporary. The assumptions used for the discontinued cash flow model include estimates for interest rates, timing and amount of cash flows and expected holding period of the ARPS.  The Company’s ARPS is classified as a long-term investment on the consolidated balance sheets, as the Company does not believe it could liquidate its security in the near term.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

4.              Investment Securities

The following is a summary of the Company’s consolidated investment securities, all of which are classified as available-for-sale. Determination of estimated fair value is based upon quoted market prices as of the dates presented.

Investments in net unrealized loss positions as of September 30, 2011 are as follows:

The amortized cost and estimated fair value of securities available-for-sale at September 30, 2011, by contractual maturity, are as follows:

The weighted-average maturity of our short-term investments as of September 30, 2011 and 2010 was approximately nine months and six months, respectively.

The Company considered a number of factors to determine whether the decline in value in its investments is other than temporary, including the length of time and the extent to which the market value has been less than cost, the financial condition of the issuer and the Company’s

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

intent to hold and ability to retain these short-term investments.  Based on these factors, the Company believes that the decline in value is temporary and primarily related to the change in market interest rates since purchase.  The Company anticipates full recovery of amortized cost with respect to these securities at maturity or sooner in the event of a change in the market interest rate environment.

5.              Stockholders’ Equity

Noncontrolling Interest

In October 2009, the Company sold 40% of its equity interest in OBI and in February 2011, pursuant to an amendment to the October 2009 financing agreement, OBI sold newly-issued shares of its common stock for gross proceeds of approximately 462.0 million New Taiwan Dollars (approximately $15.5 million based on then-current exchange rates).  The Company purchased 277.2 million New Taiwan Dollars (approximately $9.3 million based on then-current exchange rates) of the shares issued in the financing, such that the Company continued to maintain a 60% equity interest in OBI.  Pursuant to authoritative guidance, the Company accounts and reports for minority interests, the portion of OBI not owned by the Company, as noncontrolling interests and classifies them as a component of stockholders’ equity on the consolidated balance sheets of the Company.  The Company includes the net loss attributable to noncontrolling interests as part of its consolidated net loss.

The following table reconciles equity attributable to noncontrolling interest:

Warrants

In connection with a registered direct offering which occurred in March 2009, the Company sold warrants to purchase up to an aggregate of 91,533 shares of its common stock.  These warrants had an exercise price of $10.93 per share and were exercised in June 2011.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

6.              Net Loss Per Share Attributable to Common Stockholders

The following table sets forth the computation of basic and diluted net loss per share for the periods indicated:

7.              Stock Based Compensation

Optimer Pharmaceuticals, Inc.

Stock Options

In November 1998, the Company adopted the 1998 Stock Plan (the “1998 Plan”).  The Company terminated and ceased granting options under the 1998 Plan upon the closing of the Company’s initial public offering in February 2007.

In December 2006, the Company’s board of directors approved the 2006 Equity Incentive Plan (“2006 Plan”).  The 2006 Plan became effective upon the closing of the Company’s initial public offering. A total of 2,000,000 shares of the Company’s common stock were initially made available for sale under the plan.  The 2006 Plan provides for annual increases in the number of shares available for issuance thereunder on the first day of each fiscal year equal to the lesser of (i) 5% of the outstanding shares of the Company’s common stock on the last day of the immediately preceding fiscal year; (ii) 750,000 shares; or (iii) such other amount as the board of directors may determine. Pursuant to this provision, 750,000 additional shares of the Company’s common stock were reserved for issuance under the 2006 Plan on January 1, 2011, 2010 and 2009.  Under the 2006 Plan, the exercise price of options granted must at least be equal to the fair market value of the Company’s common stock on the date of grant.

In March and in June 2011, the Company’s Board of Directors approved amendments to the 2006 Plan to provide for the reservation of an additional 1,750,000 shares and 1,000,000 shares, respectively, of the Company’s common stock to be used exclusively for the grant of awards to individuals not previously an employee or non-employee director of the Company (or following a bona fide period of non-employment with the Company), as an inducement material to the individual’s entry into employment with the Company within the meaning of Rule 5635(c)(4) of the NASDAQ Listing Rules.

Options granted under both the 1998 Plan and the 2006 Plan generally expire 10 years from the date of grant (five years for a 10% or greater stockholder) and vest over a period of four years.  The exercise price of options granted must at least be equal to the fair market value of the Company’s common stock on the date of grant.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

Performance-Based Stock Options, Performance-Based Restricted Stock Units, and Stock Awards

On May 5, 2010, the Company’s Board of Directors appointed Pedro Lichtinger as its President and CEO and as a member of its Board of Directors.  Pursuant to Mr. Lichtinger’s offer letter, he received performance-based stock options to purchase up to an aggregate of 480,000 shares of common stock and performance-based restricted stock units covering up to an aggregate of 120,000 shares of common stock, which vest over time beginning on the dates the Company achieves specified development and commercialization goals.  In February 2011, one of the performance criteria was met, and, in May 2011, another one of the performance criteria was met. As a result of the accomplishment of these goals, 1/4th of the performance-based stock options and performance-based restricted stock units related to each goal will vest on the one-year anniversary of the achievement of such goal and the remaining shares will vest in 36 equal monthly installments thereafter.

Simultaneously with Mr. Lichtinger’s appointment, Michael Chang resigned as the Company’s President and CEO.  The Company entered into a consulting agreement with Dr. Chang to provide general consulting services. Pursuant to his consulting agreement and as part of his compensation, Dr. Chang received performance-based stock options to purchase up to an aggregate of 400,000 shares of common stock which vest over time beginning on the dates certain regulatory filings are accepted and approved. Dr. Chang has continued to serve as the Chairman of the Company’s Board of Directors. In January 2011, one of the performance criteria was met, and, in May 2011, another one of the performance criteria was met. As a result of the accomplishment of these goals,1/4th of the option shares related to each goal vested upon the accomplishment of such goal. The remaining shares will vest in 24 equal monthly installments over the subsequent two-year period.

In September 2011, the Company’s Board of Directors awarded performance-based restricted stock units covering an aggregate of 3,000,000 of the Company’s shares of OBI common stock to certain executives of the Company and the Chairman of the Board of Directors.  The OBI shares underlying the performance-based restricted stock units will be issued upon OBI’s achievement of a specified corporate goal and will be subject to forfeiture to the extent the recipient’s service with the Company terminates prior to the three year anniversary of the share issuance date.

Employee Stock Purchase Plan

Optimer also grants stock awards under its employee stock purchase plan (“ESPP”). Under the terms of the ESPP, eligible employees may purchase shares of Optimer’s common stock at the lesser of 85% of the fair market value of Optimer’s common stock on the offering date or the purchase date.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

Valuations

The Black-Scholes option-pricing model was developed for use in estimating the fair value of traded options and stock awards, which have no vesting restrictions and are fully transferable.  In addition, the Black-Scholes option-pricing model requires the input of subjective assumptions, including the expected stock price volatility of the underlying stock.  The following table shows the assumptions used to compute stock-based compensation expense for the stock options, performance-based stock options, performance-based restricted stock units, and ESPP purchase rights during the three and nine months ended September 30, 2011 and 2010, using the Black-Scholes option pricing model:

The risk-free interest rate assumption was based on the United States Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued.  The assumed dividend yield was based on the Company’s expectation of not paying dividends in the foreseeable future.  The weighted-average expected life of options was calculated using the simplified method.  This decision was based on the lack of relevant historical data due to the Company’s limited history.  In addition, due to the Company’s limited historical data, the Company used the historical volatility of comparable companies whose share prices are publicly available to estimate the Company’s options volatility rate.

Total stock-based compensation expense related to all of the Company’s stock options, restricted stock units, stock awards issued to employees and consultants, and employee stock purchases, recognized for the three months and nine months ended September 30, 2011 and 2010, was comprised as follows:

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

At September 30, 2011, the total unrecognized compensation expense related to unvested stock options and restricted stock units issued to employees was approximately $24.6 million and the related weighted-average period over which such expense is expected to be recognized is approximately 3.3 years.

Optimer Biotechnology, Inc.

Stock Options

In March 2010, OBI’s board of directors approved a Stock Option Plan and reserved 8.0 million shares of OBI common stock for issuance of equity awards thereunder. The Stock Option Plan provides for the issuance of stock options, restricted stock awards and stock appreciation rights to employees of OBI. The options generally vest over four years and have a maximum contractual term of ten years.

Valuations

The following table shows the assumptions used to compute stock-based compensation expense for the stock options granted by OBI during the three months and nine months ended September 30, 2011 and 2010, using the Black-Scholes option pricing model:

The risk-free interest rate assumption was based on the Central Bank of China interest rates.  The assumed dividend yield was based on OBI’s expectation of not paying dividends in the foreseeable future.  The weighted-average expected life of options was calculated using the simplified method.  This decision was based on the lack of relevant historical data due to OBI’s limited history.  Due to OBI’s limited historical data, OBI used the historical volatility of OBI’s peers whose share prices are publicly available to estimate the volatility rate of OBI stock options.

The following table summarizes the stock-based compensation expense for OBI included in each operating expense line item in Optimer’s consolidated statements of operations for the three months and nine months ended September 30, 2011 and 2010:

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

At September 30, 2011, the total unrecognized compensation expense related to unvested stock options issued to OBI employees was approximately $534,000 and the related weighted-average period over which this expense is expected to be recognized was approximately 2.6 years.

8.              Other Collaborative Agreements

Revenues from Research Grants

The Company has one active grant from the National Institute of Allergy and Infectious Diseases. This $3.0 million grant was awarded in September 2007 for three years and was subsequently extended to August 2012. The award has been used to conduct supplementary studies to the DIFICID trials to confirm narrow spectrum activity and potency of DIFICID against hypervirulent epidemic strains and to support additional toxicology studies.  The award is currently being used for microbiological studies to demonstrate the safety and efficacy of DIFICID and its major metabolite in CDAD patients and to support surveillance studies of C. difficile isolates across North America to compare the activity of DIFICID with existing CDAD treatments.  For the three months ended September 30, 2011 and 2010, the Company recognized revenues related to research grants of $61,077, and $169,137, respectively. For the nine months ended September 30, 2011 and 2010, the Company recognized revenues related to research grants of $206,010, and $824,010, respectively.

OBI has one active grant from the Taiwan Ministry of Economic Affairs (“MOEA”). This grant was for an aggregate of $27.4 million New Taiwan Dollars and was awarded in January 1, 2011 for one year. The award has been used to obtain the first 45 patients safety report for the OPT-822/821 trials.  In order to withdraw funds from the grant, OBI had to meet certain criteria and obtain a contract with the Taiwan Department of Economic Affairs. In June 2011, OBI was able to meet the criteria and received the executed contract from the Department of Economic Affairs. OBI submitted a reimbursement request to the MOEA for expenses incurred from January 2011 through September 2011. For the quarter ended September 30, 2011, OBI recognized revenues related to research grants of $12.5 million New Taiwan Dollars.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

Other Collaborative Agreements

Cubist Pharmaceuticals, Inc.

On April 5, 2011, the Company entered into a co-promotion agreement with Cubist Pharmaceuticals, Inc. (“Cubist”) pursuant to which the Company engaged Cubist as its exclusive partner for the promotion of DIFICID in the United States.  Under the terms of the agreement, the Company and Cubist have agreed to co-promote DIFICID to physicians, hospitals, long-term care facilities and other healthcare institutions as well as jointly provide medical affairs support for DIFICID. In conducting their respective co-promotion activities, each party is obligated under the agreement to commit minimum levels of personnel, and Cubist is obligated to tie a portion of the incentive compensation paid to its sales representatives to the promotion of DIFICID in the United States.  Under the terms of the agreement, the Company is responsible for the distribution of DIFICID in the United States and for recording revenue from sales of DIFICID, and agreed to use commercially reasonable efforts to maintain adequate inventory and third party logistics support for the supply of DIFICID in the United States.  In addition, Cubist agreed to not promote competing products in the United States during the term of the agreement and, subject to certain exceptions, for a specified period of time thereafter. The initial term of the agreement is two years from the date of first commercial sale of DIFICID in the United States, subject to renewal or early termination as described below.

In exchange for Cubist’s co-promotion activities and personnel commitments, the Company is obligated to pay a quarterly fee of approximately $3.75 million to Cubist ($15.0 million per year) beginning upon the commencement of the sales program of DIFICID in the United States. Cubist is also eligible to receive an additional $5.0 million in the first year after first commercial sale and $12.5 million in the second year after first commercial sale if mutually agreed upon annual sales targets are achieved, as well as a portion of the Company’s gross profits derived from net sales above the specified annual targets, if any.

The agreement may be renewed by mutual agreement of the parties for additional, consecutive one-year terms.  The Company and Cubist may terminate the agreement prior to expiration upon the uncured material breach of the agreement by the other party, upon the bankruptcy or insolvency of the other party, or in the event that actual net sales during the first year of commercial sales of DIFICID in the United States are below specified levels, subject to certain limitations.  In addition, the Company may terminate the agreement, subject to certain limitations, if (i) the Company withdraws DIFICID from the market in the United States, (ii) Cubist fails to comply with applicable laws in performing its obligations, (iii) Cubist undergoes a change of control, (iv) certain market events occur related to Cubist’s product CUBICIN® (daptomycin for injection) in the United States, or (v) Cubist undertakes certain restructuring activities with respect to its sales force.  In addition, Cubist may terminate the agreement, subject to certain limitations, if (i) the Company experiences certain supply failures in relation to the demand for DIFICID in the United States, (ii) the Company is acquired by certain types of entities, including competitors of Cubist, (iii) certain market events occur related to CUBICIN in the United States, or (iv) the Company fails to comply with applicable laws in performing its obligations.

In June 2011, the Company paid Cubist $3.75 million for the first quarterly payment which the Company started expensing as a selling, general and administrative expense in the third quarter of 2011 in connection with the launch of DIFICID.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

Astellas Pharma Europe Ltd.

In February 2011, the Company entered into a collaboration and license agreement with Astellas pursuant to which the Company granted to Astellas an exclusive, royalty-bearing license under certain of the Company’s know-how and intellectual property to develop and commercialize DIFICID in Europe, and certain other countries in the Middle East, Africa and the Commonwealth of Independent States (“CIS”). In March 2011, the parties amended the agreements to include certain additional countries in the CIS and all additional territories in Africa (all such countries and territories are referred to as the Astellas territories). Under the terms of the agreement, Astellas has agreed to use commercially reasonable efforts to develop and commercialize DIFICID in the Astellas territory at its expense, and to achieve certain additional regulatory and commercial diligence milestones with respect to DIFICID in the Astellas territory.  The Company and Astellas may also agree to collaborate in, and share data resulting from, global development activities with respect to DIFICID, in which case the Company and Astellas will be obligated to co-fund such activities.  In addition, under the terms of the agreement, Astellas granted the Company an exclusive, royalty-free license under know-how and intellectual property generated by Astellas and its sublicensees in the course of developing DIFICID and controlled by Astellas or its affiliates for use by the Company and any of the Company’s sublicensees in the development and commercialization of DIFICID outside the Astellas territory and, following termination of the agreement and subject to payment by the Company of single-digit royalties, in the Astellas territory.  In addition, under the terms of a supply agreement entered into between the Company and Astellas on the same date, the Company will be the exclusive supplier of DIFICID to Astellas for Astellas’ development and commercialization activities in the Astellas territory during the term of the supply agreement, and Astellas is obligated to pay the Company an amount equal to cost plus an agreed mark-up for such supply.

Under the terms of the license agreement with Astellas, in March 2011, Astellas paid the Company an upfront fee of $69.2 million. The Company is eligible to receive additional cash payments totaling up to 115.0 million Euros upon the achievement by Astellas of specified regulatory and commercial milestones and contingent events. Of this amount, 40 million Euros will become due 30 days subsequent to the earlier to occur of launch in two major countries or six months after EMA approval and 10 million Euros will become payable to the Company upon the launch in any country in the Astellas territory.  When determining whether or not to account for the additional cash payments under the milestone method, the Company makes a determination of whether or not each milestone is considered substantive. During this assessment the Company considers if the milestone is achieved based in whole or in part on the Company’s performance or on the occurrence of a separate outcome resulting from the Company’s performance, if there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved, and if achievement will result in additional payments being due.  Based on the Company’s assessment process it was determined that additional payments due related to regulatory approval and product launch will be accounted for under the milestone method as technological hurdles create uncertainty as to whether or not the milestones will be met and the achievement of the milestones is based in part on the occurrence of a separate outcome resulting from the Company’s performance.  In addition, the Company will be entitled to receive escalating double-

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

digit royalties ranging from the high teens to low twenties on net sales of DIFICID products in the Astellas territory, which royalties are subject to reduction in certain, limited circumstances.  Such royalties will be payable by Astellas on a product-by-product and country-by-country basis until a generic product accounts for a specified market share of the applicable DIFICID product in the applicable country.

The Company assessed the deliverables under the authoritative guidance for multiple element arrangements. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver services, a right or license to use an asset, or another performance obligation.  Once the Company identified the deliverables under the arrangement, the Company determined whether or not the deliverables can be accounted for as separate units of accounting, and the appropriate method of revenue recognition for each element. Based on the results of the Company’s analysis, the Company determined that the upfront payment was earned upon the delivery of the license and related know-how, which occurred by March 31, 2011.

The agreements with Astellas will continue in effect on a product-by-product and country-by-country basis until expiration of Astellas’ obligation to pay royalties with respect to each DIFICID product in each country in the Astellas territory, unless terminated early by either party as more fully described below.  Following expiration, Astellas’ license to develop and commercialize the applicable DIFICID product in the applicable country will become non-exclusive.  The Company and Astellas may each terminate either of the agreements prior to expiration upon the material breach of such agreement by the other party, or upon the bankruptcy or insolvency of the other party.  In addition, the Company may terminate the agreements prior to expiration in the event Astellas or any of its affiliates or sublicensees commences an interference or opposition proceeding with respect to, challenges the validity or enforceability of, or opposes any extension of or the grant of a supplementary protection certificate with respect to, any patent licensed to it, and Astellas may terminate the agreements prior to expiration for any reason on a product-by-product and country-by-country basis upon 180 days’ prior written notice to the Company.  Upon any such termination, the license granted to Astellas (in total or with respect to the terminated product or terminated country, as applicable) will terminate and revert to the Company.

Par Pharmaceutical, Inc.

The Company holds worldwide rights to DIFICID.  In February 2007, the Company repurchased the rights to develop and commercialize DIFICID in North America and Israel from Par Pharmaceutical, Inc. (“Par”) under a prospective buy-back agreement.  The Company paid Par a one-time $5.0 million milestone payment in June 2010 for the successful completion by the Company of its second pivotal Phase 3 trial for DIFICID.  The Company is obligated to pay Par a 5% royalty on any net sales by the Company, its affiliates or its licensees of DIFICID in North America and Israel, including Cubist, and a 1.5% royalty on any net sales by the Company or its affiliates of DIFICID in the rest of the world.  In addition, in the event the Company licenses its right to market DIFICID in the rest of the world, such as the license granted to Astellas, the Company will be required to pay Par a 6.25% royalty on net revenues received by it related to

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

DIFICID.  The Company is obligated to pay each of these royalties, if any, on a country-by-country basis for seven years commencing on the applicable commercial launch in each such country. In March 2011, the Company paid Par $4.3 million in royalties for net revenues received by the Company under the Astellas agreement.

Biocon Limited

In May 2010, the Company entered into a long-term supply agreement with Biocon for the commercial manufacture of DIFICID’s active pharmaceutical ingredient (“API”).   Pursuant to the agreement, Biocon agreed to manufacture and supply to the Company, up to certain limits, DIFICID API and, subject to certain conditions, the Company agreed to purchase from Biocon at least a portion of its requirements for DIFICID API in the United States and Canada. The Company previously paid to Biocon $2.5 million for certain equipment purchases and manufacturing scale-up activities, and the Company may be entitled to recover up to $1.5 million of this amount under the supply agreement in the form of discounted prices for DIFICID API.  The Company may be obligated to make additional payments to Biocon if it fails to meet the minimum purchase requirements after Biocon has dedicated certain manufacturing capacity to the production of DIFICID API and if Biocon is unable to manufacture alternative products with the dedicated capacity.  Unless both the Company and Biocon agree to extend the term of the supply agreement, it will terminate seven and a half years from the date the Company obtained marketing authorization for DIFICID in the United States.  In addition, the supply agreement may be earlier terminated (i) by either party by giving two and a half years notice after the fifth anniversary of the Effective Date or upon a material breach of the supply agreement by the other party, (ii) by the Company upon the occurrence of certain events, including Biocon’s failure to supply requested amounts of DIFICID API, or (iii) by Biocon upon the occurrence of certain events, including the Company’s failure to purchase amounts of DIFICID API indicated in binding forecasts.

Patheon Inc.

In June 2011, the Company entered into a commercial manufacturing services agreement with Patheon Inc. (“Patheon”) to manufacture and supply fidaxomicin drug products, including DIFICID, in North America, Europe and other countries, subject to agreement by the parties to any additional fees for such countries. The Company has agreed to purchase a specified percentage of its fidaxomicin product requirements for North America and Europe from Patheon or its affiliates.

The term of the agreement extends through December 31, 2016 and will automatically renew for subsequent two year terms unless either party provides a timely notice of its intent not to renew or unless the Agreement is terminated early pursuant to its terms. The Company and Patheon may terminate the Agreement prior to expiration upon the uncured material breach of the agreement by the other party or upon the bankruptcy or insolvency of the other party. In addition, the agreement will terminate with respect to any fidaxomicin product if the Company provides notice to Patheon that it no longer requires manufacturing services for such product because the product has been discontinued. Additionally, the Company may terminate the agreement, subject

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

to certain limitations, (i) with respect to any fidaxomicin product, if any regulatory authority takes any action or raises any objection that prevents the Company from importing, exporting, purchasing or selling such product, or if the Company determines to discontinue development or commercialization of such product for safety or efficacy reasons, (ii) if any regulatory authority takes an enforcement action against Patheon’s manufacturing site that relates to fidaxomicin products or that could reasonably be expected to adversely affect Patheon’s ability to supply fidaxomicin products to the Company, (iii) if Patheon is unable to deliver or supply any firm orders for any two calendar quarters during any four consecutive calendar quarters, (iv) if Patheon uses any debarred or suspended person in the performance of its service obligations under the agreement, or (v) if Patheon fails to meet certain production yield requirements in relation to fidaxomicin API.

Cempra Pharmaceuticals, Inc.

In March 2006, the Company entered into a collaborative research and development and license agreement with Cempra Pharmaceuticals, Inc. (“Cempra”).  The Company granted to Cempra an exclusive worldwide license, except in Association of Southeast Asian Nations (“ASEAN”) countries, with the right to sublicense, to the Company’s patent and know-how related to the Company’s macrolide and ketolide antibacterial program.  As partial consideration for granting Cempra the license, the Company obtained equity of Cempra and the Company assigned no value to such equity.  The Company may receive milestone payments as product candidates are developed and/or co-developed by Cempra, in addition to milestone payments based on certain sublicense revenue.  The aggregate potential amount of such milestone payments is not capped and, based in part on the number of products developed under the agreement, may exceed $24.5 million.  The Company may also receive royalty payments based on a percentage of net sales of licensed products.  The milestone payments will be triggered upon the completion of certain clinical development milestones and in certain instances, regulatory approval of products.  In consideration of the foregoing, Cempra may receive milestone payments from the Company in the amount of $1.0 million for each of the first two products the Company develops which receive regulatory approval in ASEAN countries, as well as royalty payments on the net sales of such products.  The research term of the agreement was completed in March 2008.  Subject to certain exceptions, on a country-by-country basis, the general terms of this agreement continue until the later of: (i) the expiration of the last to expire patent rights of a covered product in the applicable country or (ii) ten years from the first commercial sale of a covered product in the applicable country.  Either party may terminate the agreement in the event of a material breach by the other party, subject to prior notice and the opportunity to cure.  Either party may also terminate the agreement for any reason upon 30 days’ prior written notice provided that all licenses granted by the terminating party to the non-terminating party will survive upon the express election of the non-terminating party.

Memorial Sloan-Kettering Cancer Center

In July 2002, the Company entered into a license agreement with Memorial Sloan-Kettering Cancer Center (“MSKCC”) to acquire, together with certain nonexclusive licenses, exclusive, worldwide licensing and sublicensing rights to certain patented and patent-pending carbohydrate-

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

based cancer immunotherapies.  As partial consideration for the licensing rights, the Company paid to MSKCC a one-time fee consisting of both cash and 55,383 shares of its common stock.  In anticipation of the various transactions involving OBI which the Company completed in October 2009, the Company assigned its rights and obligations under this agreement to OBI. Under the agreement, which was amended in June 2005, OBI owes MSKCC milestone payments in the following amounts for each licensed product: (i) $500,000 upon the commencement of Phase 3 clinical studies, (ii) $750,000 upon the filing of the first NDA, (iii) $1.5 million upon obtaining marketing approval in the United States and (iv) $1.0 million upon obtaining marketing approval in each and any of Japan and certain European countries, but only to the extent that OBI, and not a sublicensee, achieves such milestones.  OBI may owe MSKCC royalties based on net sales generated from the licensed products and income OBI sources from its sublicensing activities, which royalty payments are credited against a minimum annual royalty payment OBI owes to MSKCC during the term of the agreement.

Scripps Research Institute

In July 1999, the Company acquired exclusive, worldwide rights to its OPopS technology from the Scripps Research Institute (“TSRI”).  This agreement includes the license to the Company of patents, patent applications and copyrights related to OPopS technology.  The Company also acquired, pursuant to three separate license agreements with TSRI, exclusive, worldwide rights to over 20 TSRI patents and patent applications related to other potential drug compounds and technologies, including HIV/FIV protease inhibitors, aminoglycoside antibiotics, polysialytransferase, selectin inhibitors, nucleic acid binders, carbohydrate mimetics and osteoarthritis.  Under the four agreements with TSRI, the Company paid TSRI license fees consisting of an aggregate of 239,996 shares of its common stock with a deemed aggregate fair market value of $46,400, as determined on the dates of each such payment.  In October 2009, the Company assigned to OBI one of the agreements with TSRI related to the Company’s OPT-88 product candidate, which after further evaluation OBI decided not to pursue.  In February 2011, the license agreement related to OPT-88 was terminated and OBI returned the patents related to OPT-88. Under each of the three remaining agreements, the Company owes TSRI royalties based on net sales by the Company, its affiliates and sublicensees of the covered products and royalties based on revenue the Company generates from sublicenses granted pursuant to the agreements.  For the first licensed product under each of the three agreements, the Company also will owe TSRI payments upon achievement of certain milestones.  In two of the three TSRI agreements, the milestones are the successful completion of a Phase 2 trial or its foreign equivalent, the submission of an NDA or its foreign equivalent and government marketing and distribution approval.  In the remaining TSRI agreement, the milestones are the initiation of a Phase 3 trial or its foreign equivalent, the submission of an NDA or its foreign equivalent and government marketing and distribution approval.  The aggregate potential amount of milestone payments the Company may be required to pay TSRI under the remaining TSRI agreements is approximately $11.1 million.

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Optimer Pharmaceuticals, Inc.

Notes to Consolidated Financial Statements (continued)

(unaudited)

Optimer Biotechnology, Inc.

In October 2009, the Company entered into certain transactions involving OBI, then the Company’s wholly-owned subsidiary, to provide funding for the development of two of the Company’s early-stage, non-core programs.  The transactions with OBI included an Intellectual Property Assignment and License Agreement, pursuant to which the Company assigned to OBI certain patent rights, information and know-how related to OPT-88 and OPT-822/821.  In anticipation of these transactions, the Company also assigned, and OBI assumed, the Company’s rights and obligations under related license agreements with MSKCC and TSRI.  Under this agreement, the Company is eligible to receive up to $10 million in milestone payments for each product developed under the development programs and is also eligible to receive royalties on net sales of any product which is commercialized under the programs.  The term of the Intellectual Property Assignment and License Agreement continues until the last to expire of the patents assigned by the Company to OBI and the patents licensed to OBI under the TSRI and MSKCC agreements. After further evaluation, OBI determined not to pursue additional development of OPT-88 and in February 2011, OBI and TSRI agreed to terminate the license agreement and OBI returned the related OPT-88 patents to TSRI. To provide capital for OBI’s product development efforts, the Company and OBI also entered into a financing agreement with a group of new investors.  Simultaneously, the Company sold 40 percent of its existing OBI shares to the group of new investors, and the Company and the new investors also purchased new OBI shares.  The financing agreement also contemplated an additional financing pursuant to which the Company and the new investors would invest approximately an additional $184.8 million New Taiwan Dollars and $277.2 million New Taiwan Dollars, respectively, in exchange for new OBI shares. In February 2011, pursuant to an amendment to the October 2009 financing agreement, OBI completed the second financing and sold newly-issued shares of its common stock for gross proceeds of approximately 462.0 million New Taiwan Dollars (approximately $15.5 million based on then-current exchange rates).  The Company purchased 277.2 million New Taiwan Dollars (approximately $9.3 million based on then-current exchange rates) of the shares issued in the second financing, such that the Company maintained its 60% equity interest in OBI.

9.              Subsequent Events

In November 2011, the Company filed a new drug submission with the Therapeutic Products Directorate of Health Canada (“Health Canada”) for DIFICID for the treatment of CDAD.  Health Canada awarded the Company priority review of the DIFICID new drug submission enabling an accelerated review process.  In preparation for potentially commercializing DIFICID in Canada, the Company established a wholly-owned subsidiary, Optimer Pharmaceuticals Canada, Inc. located in Toronto, Canada.

On November 1, 2011, the Company made a strategic decision to discontinue the clinical development of Pruvel (prulifloxacin) as a treatment for traveler’s diarrhea. The Company notified Nippon Shinyaku, Co. Ltd. that it was terminating the related license agreement and the Company will return all rights to the compound to Nippon Shinyaku.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion and analysis should be read in conjunction with our consolidated financial statements and accompanying notes appearing elsewhere in this report, as well as the audited financial statements and accompanying notes included in our annual report on Form 10-K for the fiscal year ended December 31, 2010, as filed with the Securities and Exchange Commission, or SEC.  This discussion and other parts of this report may contain forward-looking statements based upon current expectations that involve risks and uncertainties.  Our actual results and the timing of selected events could differ materially from those anticipated in these forward-looking statements as a result of several factors, including those set forth under “Risk Factors” and elsewhere in this report.

Overview

We are a biopharmaceuticals company currently focused on commercializing and further developing our antibiotic product DIFICID™ (fidaxomicin).  DIFICID is the first antibacterial drug indicated for Clostridium difficile-associated diarrhea, or CDAD, to be approved in the United States in nearly 30 years. It is indicated for the treatment of CDAD in adults 18 years of age or older. We are currently marketing DIFICID in the United States through our own sales force and through our co-promotion agreement with Cubist Pharmaceuticals, Inc, or Cubist. In addition, we have filed a Marketing Authorization Application with the European Medicines Agency, or EMA, for approval of fidaxomicin, and the Committee for Medicinal Products for Human Use of the EMA recently expressed a positive opinion for fidaxomicin tablets for the treatment of adults suffering with Clostridium difficile infection, or CDI, also known as CDAD.  If approved by the EMA, we expect that DIFICID will be marketed by Astellas under the name DIFICLIR™ in Europe.

In February 2011, we entered into an exclusive collaboration and license agreement with Astellas to develop and commercialize DIFICID in Europe, Africa and certain other countries in the Middle East and the Commonwealth of Independent States, or CIS, which we refer to as the Astellas territory. In return for an exclusive license to DIFICID in the Astellas territory, Astellas paid to us an upfront cash payment of $69.2 million and we are eligible to receive additional cash payments totaling up to 115 million Euros upon the achievement of certain regulatory and commercial milestones and contingent events.  Furthermore, we will be entitled to receive escalating double-digit royalties ranging from the high teens to low twenties on net sales of DIFICID in the Astellas territory, if approved.  Astellas is responsible for all future costs associated with the development and commercialization of DIFICID in the Astellas territory including the costs associated with the MAA for DIFICID in Europe.  In connection with the collaboration and license agreement, we also entered into a supply agreement with Astellas pursuant to which we will be the exclusive supplier of DIFICID to Astellas in the Astellas territory and Astellas is obligated to pay us an amount equal to cost plus an agreed mark-up for such supply.

In April 2011, we entered into a co-promotion agreement with Cubist pursuant to which we engaged Cubist as our exclusive partner for the promotion of DIFICID in the United States.  Under the terms of the agreement, we and Cubist have agreed to co-promote DIFICID to physicians, hospitals, long-term care facilities and other healthcare institutions as well as jointly

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provide medical affairs support for DIFICID. Under the terms of the agreement, we will be responsible for the distribution of DIFICID in the United States and for recording revenue from sales of DIFICID, and we agreed to use commercially reasonable efforts to maintain adequate inventory and third party logistics support for the supply of DIFICID in the United States.  The initial term of the agreement is two years from the date of first commercial sale of DIFICID in the United States, subject to renewal or early termination.

In exchange for Cubist’s co-promotion activities and personnel commitments, we are obligated to pay a quarterly fee of approximately $3.75 million to Cubist ($15.0 million per year) upon the commencement of the DIFICID sales program in the United States.  Cubist is also eligible to receive an additional $5.0 million in the first year after first commercial sale and $12.5 million in the second year if mutually agreed upon annual sales targets are achieved, as well as a portion of our gross profits derived from net sales above the specified annual targets, if any.

We are developing additional product candidates using our proprietary technology, including our OPopS drug discovery platform. OPopS is a computer-aided technology that allows the development of potential drug candidates through carbohydrate mediated medicinal chemistry and enables the rapid synthesis of a wide variety of proprietary molecules. It includes GlycoOptimization, which enables the modification of a carbohydrate group on an existing drug to improve its properties, and De Novo Glycosylation, which introduces new carbohydrate groups on existing drugs to create new patentable compounds with improvement of pharmacokinetics.

We previously acquired exclusive rights to OPT-822/821, a combination of a novel carbohydrate-based cancer immunotherapy together with an adjuvant, which we licensed from Memorial Sloan-Kettering Cancer Center, or MSKCC.  In October 2009, we assigned to OBI certain of our patent rights and know-how related to OPT-822/821 and also assigned to OBI our rights and obligations under a related license agreement with MSKCC. In April 2010, OBI filed an investigational new drug application, or IND, in Taiwan for OPT-822/821, and in January 2011, OBI initiated a Phase 2/3 clinical trial for the treatment of metastatic breast cancer and is currently conducting the clinical trial in Taiwan and Hong-Kong.  We have the right to receive up to $10 million from OBI in future milestone payments related to the development of OPT-822/821 as well as royalties on net sales of this product candidate.  In February 2011, pursuant to an amendment to an October 2009 financing agreement, OBI sold newly-issued shares of its common stock for gross proceeds of approximately 462.0 million New Taiwan Dollars (approximately $15.5 million based on then-current exchange rates).  We purchased 277.2 million New Taiwan Dollars (approximately $9.3 million based on then-current exchange rates) of the shares issued in the financing, and we currently maintain a 60% equity interest in OBI.

We were incorporated in November 1998.  Since inception, we have focused on developing and commercializing DIFICID. We have never been profitable in any fiscal year and have incurred significant net losses since our inception.  As of September 30, 2011, we had an accumulated deficit of $228.3 million.  These losses have resulted principally from costs incurred in connection with research and development activities, including the costs of clinical trial activities, license fees and general and administrative expenses.  We expect to continue to incur

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operating losses for the next several years as we pursue the commercialization of DIFICID, conduct post-marketing and Phase 4 studies and undertake life cycle management projects for DIFICID. We may also acquire or in-license additional products or product candidates, technologies or businesses that are complementary to our own.

Critical Accounting Policies

Our Management’s Discussion and Analysis of Financial Condition and Results of Operations is based on our consolidated financial statements, which have been prepared in conformity with generally accepted accounting principles in the United States.  The preparation of these consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities, expenses and related disclosures.  Actual results could differ from those estimates. While our significant accounting policies are described in more detail in Note 2 of the Notes to Consolidated Financial Statements appearing elsewhere in this report, we believe the following accounting policies to be critical to the judgments and estimates used in the preparation of our consolidated financial statements.

Inventory

Inventory is stated at the lower of cost or market.  Cost is determined in a manner which approximates the first-in, first-out (FIFO) method. We capitalize inventory produced in preparation for product launches upon FDA approval when costs are expected to be recoverable through the commercialization of the product.  We reserve for potentially excess, dated or obsolete inventories based on an analysis of inventory on hand compared to forecasts of future sales. As of September 30, 2011, inventories consist of $954,455 in raw materials, $479,975 in work in progress and $810,732 in finished goods.

Revenue Recognition

DIFICID is available only through three major wholesalers, AmerisourceBergen Corporation, Cardinal Health, Inc., and McKesson Corporation, and regional wholesalers that provide the DIFICID to hospital and retail pharmacies, and long-term care facilities. We apply the revenue recognition guidance in Staff Accounting Bulletin (“SAB”) 104 and do not recognize revenue from product sales until there is persuasive evidence of an arrangement, delivery has occurred, title has passed to the customer, the price is fixed and determinable, the buyer is obligated to pay us, the obligation to pay is not contingent on resale of the product, the buyer has economic substance apart from us, we have no obligation to bring about the sale of the product, the amount of returns can be reasonably estimated and collectability is reasonably assured. We recognize product sales of DIFICID upon delivery of product to the wholesalers.

During the three months ended and nine months ended September 30, 2011, the $10.6 million in net product revenue to wholesalers reflected a total of 4,335 DIFICID treatments. 2,505 DIFICID treatments were shipped to hospitals, retail pharmacies and long-term care facilities.  As of September 30, 2011, 535 hospitals had ordered DIFICID with 304 of those hospitals having placed DIFICID on their formularies.

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Our net revenues represent total revenues less allowances for customer credits, including estimated rebates, discounts and returns. These allowances are established by management as its best estimate based on available information and will be adjusted to reflect known changes in the factors that impact such allowances. Allowances for rebates, discounts and returns are established based on the contractual terms with customers, communications with customers as well as expectations about the market for the product and anticipated introduction of competitive products.  Product shipping and handling costs are included in cost of sales.

Product Sales Allowances.  We establish reserves for prompt payment discounts and fee for service arrangements with our contracted wholesalers, government rebates, product returns and other applicable allowances.  Reserves established for these discounts and allowances are classified as a reduction of accounts receivable.

Allowances against receivable balances primarily relate to prompt payment discounts and are recorded at the time of sale, resulting in a reduction in product sales revenue.  Accruals related to government rebates, product returns and other applicable allowances are recognized at the time of sale, resulting in a reduction in product sales revenue and the recording of an increase in accrued expenses.

Prompt Payment Discounts.  We offer a prompt payment discount to our contracted wholesalers.  Since we expect our customers will take advantage of this discount, we accrue 100% of the prompt payment discount that is based on the gross amount of each invoice, at the time of sale.  The accrual is adjusted quarterly to reflect actual earned discounts.

Government Rebates and Chargebacks.  We estimate government mandated rebates and discounts relating to into federal and state programs such as Medicaid, Veterans’ Administration, or VA, and Department of Defense programs, the Medicare Part D Coverage Discount Program, as well as with respect to certain other qualifying federal and state government programs.  We estimate the amount of these reductions based on historical trends for similar competitive products, until such time as DIFICID patient data, actual sales data and market research data related to payor mix has reached an established steady state.  These allowances are adjusted each period based on actual experience.

Medicaid rebate reserves relate to our estimated obligations to states under statutory “best price” obligations which may also include supplemental rebate agreements with certain states.  Rebate accruals are recorded during the same period in which the related product sales are recognized.  Actual rebate amounts are determined at the time of claim by the state, and we will generally make cash payments for such amounts after receiving billings from the state.

VA rebates or chargeback reserves represent our estimated obligations resulting from contractual commitments to sell DIFICID to qualified healthcare providers at a price lower than the list price charged to our distributor.  The distributor will charge us for the difference between what the distributor pays for the product and the ultimate selling price to the qualified healthcare provider.  Rebate accruals are established during the same period in which the related product sales are recognized. Actual chargeback amounts for Public Health Service are determined at the time of resale to the qualified healthcare provider from the distributor, and we will generally issue credits for such amounts after receiving notification from the distributor.

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Although allowances and accruals are recorded at the time of product sale, certain rebates will be generally paid out, on average, up to six months or longer after the sale.  Reserve estimates are evaluated quarterly and, if necessary, adjusted to reflect actual results.  Any such adjustments will be reflected in our operating results in the period of the adjustment.

Product Returns.  Our policy is to accept returns of DIFICID for six months prior to and twelve months after the product expiration date.  We also permit returns if the product is damaged or defective when received by its customers. We will provide a credit for such returns to customers with whom we have a direct relationship. Once product is dispensed it cannot be returned, but we allow partial returns in states where such returns are mandated. We do not exchange product from inventory for the returned product.

Allowances for product returns are recorded during the period in which the related product sales are recognized, resulting in a reduction to product revenue.  We estimate product returns based upon historical trends in the pharmaceutical industry and trends for similar products sold by others.

Collaborations, Milestones and Royalties

In order to determine the revenue recognition for contingent milestones, we evaluate the contingent milestones using the criteria as provided by the Financial Accounting Standards Boards, or FASB, guidance on the milestone method of revenue recognition at the inception of a collaboration agreement.

Accounting Standard Codification (“ASC”) Topic 605-28, Revenue Recognition — Milestone Method (“ASC 605-28”), established the milestone method as an acceptable method of revenue recognition for certain contingent event-based payments under research and development arrangements.  Under the milestone method, a payment that is contingent upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved.  A milestone is an event (i) that can be achieved based in whole or in part on either our performance or on the occurrence of a specific outcome resulting from our performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved, and (iii) that would result in additional payments being due to us.  The determination that a milestone is substantive is judgmental and is made at the inception of the arrangement.  Milestones are considered substantive when the consideration earned from the achievement of the milestone is (i) commensurate with either our performance to achieve the milestone or the enhancement of value of the item delivered as a result of a specific outcome resulting from our performance to achieve the milestone, (ii) relates solely to past performance and (iii) is reasonable relative to all deliverables and payment terms in the arrangement.

Other contingent event-based payments received for which payment is either contingent solely upon the passage of time or the results of a collaborative partner’s performance are not considered milestones under ASC 605-28.  In accordance with ASC Topic 605-25, Revenue Recognition — Multiple-Element Arrangements (“ASC 605-25”), such payments will be recognized as revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; price is fixed or determinable; and collectability is reasonably assured.

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Revenues recognized for royalty payments, if any, are recognized as earned in accordance with the terms of various research and collaboration agreements.

For collaboration agreements with multiple deliverables, we recognize collaboration revenues and expenses by analyzing each element of the agreement to determine if it is to be accounted for as a separate element or single unit of accounting. If an element is to be treated separately for revenue recognition purposes, the revenue recognition principles most appropriate for that element are applied to determine when revenue is to be recognized. If an element is not to be treated separately for revenue recognition purposes, the revenue recognition principles most appropriate for the bundled group of elements are applied to determine when revenue is to be recognized.

Cash received in advance of services being performed is recorded as deferred revenue and recognized as revenue as services are performed over the applicable term of the agreement.  In connection with certain research collaboration agreements, revenues are recognized from non-refundable upfront fees, which we do not believe are specifically tied to a separate earnings process, ratably over the term of the agreement.  Research fees are recognized as revenue as the related research activities are performed.

With respect to revenues derived from reimbursement of direct out-of-pocket expenses for research costs associated with grants, where we act as a principal, with discretion to choose suppliers, bear credit risk and perform part of the services required in the transaction, we record revenue for the gross amount of the reimbursement. The costs associated with these reimbursements are reflected as a component of research and development expense in the consolidated statements of operations.

Research and Development

Research and development costs are expensed as incurred and consist primarily of costs associated with clinical trials, compensation, including stock-based compensation, and other expenses related to research and development, including personnel costs, facilities costs and depreciation.

When nonrefundable payments for goods or services to be received in the future for use in research and development activities are made, we defer and capitalize these types of payments. The capitalized amounts are expensed when the related goods are delivered or the services are performed.

Stock-Based Compensation

The FASB authoritative guidance requires that share-based payment transactions with employees be recognized in the financial statements based on their fair value and recognized as compensation expense over the vesting period.  We used the modified prospective method and accordingly we did not restate the results of operations for the prior periods.

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Total consolidated stock-based compensation expense of $2.7 million and $1.9 million was recognized in the three months ended September 30, 2011 and 2010, respectively.  Total consolidated stock-based compensation expense of $7.4 million and $5.0 million was recognized in the nine months ended September 30, 2011 and 2010, respectively.  The stock-based compensation expense recognized during the three months and nine months ended September 30, 2011 included expense from performance-based stock options and restricted stock units.

Stock-based compensation expense is estimated as of the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which generally represents the vesting period. We estimate the fair value of our stock options using the Black-Scholes option-pricing model and the fair value of our stock awards based on the quoted market price of our common stock.

Estimating the fair value for stock options requires judgment, including estimating stock-price volatility, expected term, expected dividends and risk-free interest rates. Due to Optimer’s and OBI’s limited historical data, the expected volatility incorporates the historical volatility of comparable companies whose share prices are publicly available. The average expected term is calculated using the Simplified Method for Estimating the Expected Term.  Expected dividends are estimated based on Optimer’s and OBI’s dividend history as well as Optimer’s and OBI’s current projections. The risk-free interest rate for Optimer is based on the United States Treasury rate for U.S. Treasury zero-coupon bonds with maturities similar to the periods approximating the expected terms of the options. The risk-free rate for OBI is based on the Central Bank of China interest rates. These assumptions are updated on an annual basis or sooner if there is a significant change in circumstances that could affect these assumptions.

Equity instruments issued to non-employees are recorded at their fair value and are periodically revalued as the equity instruments vest and are recognized as expense over the related service period.

Income taxes

We estimate income taxes based on the jurisdictions where we conduct business.  Significant judgment is required in determining our worldwide income tax provision.  We estimate our current tax liability and assess temporary differences that result from differing treatments of certain items for tax and accounting purposes.  These differences result in net deferred tax assets and liabilities.  We then assess the likelihood that deferred tax assets will be realized.  A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized.  We review the need for a valuation allowance each interim period to reflect uncertainties about whether we will be able to utilize deferred tax assets before they expire.  The valuation allowance analysis is based on estimates of taxable income for the jurisdictions in which we operate and the periods over which our deferred tax assets may be realized.  Changes in our valuation allowance could result in material increases or decreases in our income tax expense in the period such changes occur, which could have a material impact on our operating results.

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We estimate that our federal and state taxable income for the current year will be fully offset by net operating losses and research and development credit carryovers.  As such, no current tax provision has been recorded.  We also have recorded a full valuation allowance for the remaining net deferred tax benefits.

We have completed a section 382/383 analysis regarding the limitation of the net operating losses and credit carryovers and have considered the annual limitation when determining the amount available for utilization in the current year.

We recognize and measure benefits for uncertain tax positions using a two-step approach.  The first step is to evaluate the tax position taken and expected to be taken in a tax return by determining if the weight of available evidence indicates that it is more likely than not that the tax position will be sustained upon audit, including resolution of any related appeals or litigation processes.  For tax positions that are more likely than not to be sustained upon audit, the second step is to measure the tax benefit as the largest amount that has more than a 50% chance of being realized upon settlement.  Significant judgment is required to evaluate uncertain tax positions.  We evaluate uncertain tax positions on a quarterly basis.  The evaluations are based upon a number of factors, including changes in facts or circumstances, changes in tax law, correspondence with tax authorities during the course of audits and effective settlement of audit issues.  Changes in recognition or measurement of uncertain tax positions could result in material increases or decreases in our income tax expense in the period such changes occur, which could have a material impact on our effective tax rate and operating results.

Results of Operations

Comparison of Three Months Ended September 30, 2011 and 2010

Revenues

Total revenues for the three months ended September 30, 2011 and 2010 were $11.1 million and $669,000, respectively. The increase was primarily due to recognition of $10.6 million of net product revenue from the sale of DIFICID. We launched DIFICID, our first commercial product, in July 2011.

Cost and expenses

Cost of product sales.  Cost of product sales for the three months ended September 30, 2011 primarily represents the 5% royalty due to Par on net sales of DIFICID in the United States.  A significant portion of the cost of DIFICID sold during the quarter was expensed when manufactured in the first quarter of 2011 since DIFICID had not been approved by the FDA at that time.

Research and development expense.  Research and development expense for the three months ended September 30, 2011 and 2010 was $10.4 million and $8.1 million, respectively, an increase of $2.3 million. The increase was primarily due to higher health economics research, pharmacovigilance, medical affairs, and publication expenses. The increase was offset by a decrease in DIFICID and Pruvel development expenses.

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Selling, general and administrative expense. Selling, general and administrative expense for the three months ended September 30, 2011 and 2010 was $26.9 million and $4.8 million respectively, an increase of $22.1 million. The increase was related to the build-up of our commercial infrastructure for the launch of DIFICID as well as a significant increase in related marketing expenses in 2011.  We hired approximately 100 hospital account managers from May through July 2011 which significantly increased our compensation expenses and related personnel costs. In addition, we expensed $2.9 million related to the Cubist service fee as part of our co-promotion agreement.

Interest income and other, net. Interest income and other, net for the three months ended September 30, 2011 and 2010 was $108,000 and $23,000, respectively. The increase was primarily due to a higher cash balance over the same period in the prior year.

Comparison of Nine Months Ended September 30, 2011 and 2010

Revenues

Total revenues for the nine months ended September 30, 2011 and 2010 were $80.4 million and $1.3 million, respectively. The increase was due to recognition of $10.6 million of net product revenue from the sale of DIFICID. We launched DIFICID, our first commercial product, in July 2011. We also received a $69.2 upfront payment from Astellas under the DIFICID collaboration and license agreement during the nine months ended September 30, 2011.  The payment was earned upon delivery of the license and related know-how which occurred in the quarter ended March 31, 2011.

Cost and expenses

Cost of product sales.  Cost of product sales for the nine months ended September 30, 2011 primarily represents the 5% royalty due to Par on net sales of DIFICID in the United States.  A significant portion of the cost of DIFICID sold during the nine months ended September 30, 2011 was expensed when manufactured in the first quarter of 2011, since DIFICID had not been approved by the FDA at that time.

Cost of licensing.  Cost of licensing for the nine months ended September 30, 2011 was $4.3 million.  This amount represents a 6.25% royalty payment we made to Par based on net revenue from the Astellas upfront payment. We did not have cost of licensing expense in the same period of the prior year.

Research and development expense.  Research and development expense for the nine months ended September 30, 2011 and 2010 was $29.1 million and $25.9 million, respectively, an increase of approximately $3.2 million.  The increase was primarily due to higher health economics research, pharmacovigilance, medical affairs, publication expenses as well as higher research and development expenses by OBI for its Phase 2/3 breast cancer clinical trial. The increase was partially offset by a $5.0 million milestone payment due to Par in the prior year period for the successful completion of the second DIFICID Phase 3 trial.

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Selling, general and administrative expense. Selling, general and administrative expense for the nine months ended September 30, 2011 and 2010 was $53.5 million and $11.8 million respectively, an increase of $41.7 million. The increase was related to the build-up of our commercial infrastructure for the launch of DIFICID as well as a significant increase in related marketing expenses in 2011.  We hired approximately 100 hospital account managers as well as sales support and marketing personnel and thus significantly increased our compensation expenses and related personnel costs. In addition, we expensed $2.9 million related to the Cubist service fee as part of our co-promotion agreement.

Interest income and other, net. Interest income and other, net for the nine months ended September 30, 2011 and 2010 was $228,000 and $101,000, respectively. The increase was primarily due to a higher cash balance over the same period in the prior year.

Liquidity and Capital Resources

Sources of Liquidity

Prior to our launch of DIFICID in July 2011, our operations have been financed primarily through the sale of equity securities.  Through September 30, 2011, we received gross proceeds of approximately $333.8 million from the sale of shares of our preferred and common stock in various private and public financing transactions.

In March 2011, pursuant to our collaboration and license agreement with Astellas, we received approximately $69.2 million as an upfront payment from Astellas.

Until required for operations, we invest a substantial portion of our available funds in money market funds, U.S. government instruments and other readily marketable debt instruments, all of which are investment-grade quality.  We have established guidelines relating to diversification and maturities of our investments to preserve principal and maintain liquidity.

Cash Flows

As of September 30, 2011, our consolidated cash, cash equivalents and short-term investments totaled approximately $129.4 million as compared to $49.4 million as of December 31, 2010, an increase of approximately $80.0 million.  The increase in our cash, cash equivalents and short-term investments was primarily due to our receipt of net proceeds of $73.1 million in February 2011 in a public common stock offering and a $69.2 million upfront payment from Astellas in March 2011 in connection with a collaboration and license agreement for DIFICID. Additionally, in February 2011 OBI raised approximately $15.5 million in gross proceeds in a private placement of common shares. Of our consolidated cash, cash equivalents and short-term investments, $15.0 million was held by OBI as of September 30, 2011.

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Although we started selling DIFICID in July 2011, we cannot be certain if, when or to what extent we will receive meaningful cash inflows from our commercialization activities.  We expect our commercialization expenses to be substantial and to increase over the next few years. We also expect to continue to incur development expenses as we pursue life cycle management opportunities and build our pipeline.

On April 5, 2011, we entered into a co-promotion agreement with Cubist pursuant to which we engaged Cubist as our exclusive partner for the promotion of DIFICID in the United States.  Under the terms of the agreement, we and Cubist have agreed to co-promote DIFICID to physicians, hospitals, long-term care facilities and other healthcare institutions as well as jointly provide medical affairs support for DIFICID. In exchange for Cubist’s co-promotion activities and personnel commitments, we are obligated to pay a quarterly fee of approximately $3.75 million to Cubist ($15.0 million per year) which we began paying upon the commencement of the DIFICID sales program in the United States. Cubist is also eligible to receive an additional $5.0 million in the first year after first commercial sale and $12.5 million in the second year after first commercial sale if mutually agreed upon annual sales targets are achieved, as well as a portion of our gross profits derived from net sales above the specified annual targets, if any.

In February 2011, we entered into a collaboration and license agreement with Astellas pursuant to which we granted to Astellas an exclusive, royalty-bearing license under certain of our know-how and intellectual property to develop and commercialize DIFICID in the Astellas territory. Under the terms of the license agreement with Astellas, Astellas paid to us an upfront fee of $69.2 million.We are eligible to receive additional cash payments totaling up to 115.0 million Euros upon the achievement by Astellas of specified regulatory and commercial milestones with 40 million Euros of this amount due 30 days following the earlier to occur of launch of DIFICID in two major territories or six months after EMA approval and 10 million Euros payable to us upon launch of DIFICID in any Astellas territory.  In addition, we will be entitled to receive escalating double-digit royalties ranging from the high teens to low twenties on net sales of DIFICID products in the Astellas territory, which royalties are subject to reduction in certain, limited circumstances.  Such royalties will be payable by Astellas on a product-by-product and country-by-country basis until a generic product accounts for a specified market share of the applicable DIFICID product in the applicable country.

In May 2010, we entered into a long-term supply agreement with Biocon for the commercial manufacture of DIFICID’s active pharmaceutical ingredient, or API. Pursuant to the agreement, Biocon agreed to manufacture and supply to us, up to certain limits, DIFICID API and, subject to certain conditions, we agreed to purchase from Biocon at least a portion of our requirements for DIFICID API in the United States and Canada.  We previously paid to Biocon $2.5 million for certain equipment purchases and manufacturing scale-up activities, and we may be entitled to recover up to $1.5 million of this amount under the supply agreement in the form of discounted prices for DIFICID API.  We may be obligated to make additional payments to Biocon if we fail to meet minimum purchase requirements after Biocon has dedicated certain manufacturing capacity to the production of DIFICID API and if Biocon is unable to manufacture alternative products with the dedicated capacity.

In October 2008, our Compensation Committee adopted a Severance Benefit Plan covering certain eligible employees of the Company, including executive officers.  In May 2010, the Severance Benefit Plan was amended and restated.  Pursuant to the plan, upon an involuntary

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termination other than for cause or a constructive termination, an eligible employee may be entitled to receive specified severance benefits. The benefits may include cash severance payments and acceleration of stock award vesting.  The level of benefits provided under the plan depends upon an eligible employee’s position and years of service, and whether the termination is related to a change in control.

In February 2007, we regained worldwide rights to DIFICID from Par under a prospective buy-back agreement.  We paid Par a one-time $5.0 million milestone payment in June 2010 for our successful completion of the second Phase 3 trial for DIFICID.  We are obligated to pay Par a 5% royalty on net sales by us or our affiliates of DIFICID in North America and Israel, and a 1.5% royalty on net sales by us or our affiliates of DIFICID in the rest of the world.  In addition, we are required to pay Par a 6.25% royalty on net revenues we receive from licensees of our right to market DIFICID in the rest of the world.  We are obligated to pay each of these royalties, if any, on a country-by-country basis for seven years commencing on the applicable commercial launch in each such country. In March 2011, we paid Par a $4.3 million royalty payment associated with the upfront payment we received under the Astellas agreement.

Funding Requirements

Our future capital uses and requirements depend on numerous factors including, but not limited to, the following:

·                  our ability to successfully market and sell DIFICID;

·                  the costs of establishing, maintaining and managing our commercial infrastructure including our sales or distribution capabilities and the timing of such efforts;

·                  the amount and timing of payments we may receive or be required to make under strategic collaborations, including licensing, co-promotion and other arrangements;

·                  our decision to partner or license DIFICID or commercialize DIFICID ourselves in countries outside the United States and the Astellas territory;

·                  our decision to conduct future clinical trials, including the timing and progress of such clinical trials;

·                  our ability to establish and maintain strategic collaborations, including licensing and other arrangements;

·                  the costs of preparing and pursuing applications for regulatory approvals and the timing of such approvals;

·                  the costs involved in prosecuting, enforcing or defending patent claims or other intellectual property rights; and

·                  the extent to which we in-license, acquire or invest in other indications, products, technologies and businesses.

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We believe that our existing cash and cash equivalents will be sufficient to meet our capital requirements for at least the next 12 months.

Until we can generate significant cash from our operations, we expect to continue to fund our operations with existing cash resources, revenues from sales of DIFICID in the United States and revenues from existing and future collaboration agreements.  In addition, we may finance future cash needs through the sale of additional equity securities, strategic collaboration agreements and debt financing.  However, we may not be successful in completing future equity financings, in entering into additional collaboration agreements, in receiving milestone or royalty payments under new or existing collaboration agreements, in obtaining new government grants or in obtaining debt financing.  In addition, we cannot be sure that our existing cash and investment resources will be adequate, that financing will be available when needed or that, if available, financing will be obtained on terms favorable to us or our stockholders.  The credit markets continue to be volatile which has generally made equity and debt financing more difficult to obtain, and may negatively impact our ability to complete financing transactions.  Having insufficient funds may require us to delay, scale-back or eliminate some or all of our planned commercialization activities and development programs, relinquish some or even all of our rights to product candidates at an earlier stage of development or negotiate less favorable terms for rights to our products or product candidates than we would otherwise choose.  Failure to obtain adequate financing also may adversely affect our ability to operate as a going concern.  If we raise funds by issuing equity securities, substantial dilution to existing stockholders would likely result.  If we raise funds by incurring debt, the terms of the debt may involve significant cash payment obligations as well as covenants and specific financial ratios that may restrict our ability to operate our business.

Item 3. Quantitative and Qualitative Disclosures about Market Risk

Cash Equivalents and Marketable Securities Risk

Our cash and cash equivalents and short-term investments as of September 30, 2011 consisted primarily of money market funds and U.S. government instruments and other readily marketable debt instruments.  Our primary exposure to market risk is interest income sensitivity, which is affected by changes in the general level of U.S. interest rates.  The primary objective of our investment activities is to preserve principal while at the same time maximizing the income we receive from our investments without significantly increasing risk.  A hypothetical ten percent change in interest rates during the quarter ended September 30, 2011 would have resulted in an approximately $14,000 change in net income. Accordingly, we would not expect our operating results or cash flows to be affected to any significant degree by a sudden change in market interest rates applicable to our securities portfolio.  In general, money market funds are not subject to market risk because the interest paid on such funds fluctuates with the prevailing interest rate.

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Fair Value Measurements

All of our investment securities are available-for-sale securities and are reported on the consolidated balance sheet at market value except for one auction rate preferred security, or ARPS, with a par value of approximately $1.0 million. As a result of the negative conditions in the global credit markets, our ARPS is currently not liquid.  In the event we need to access the funds that are in an illiquid state, we will not be able to do so without a loss of principal, until the security is redeemed by the issuer or it matures.

Foreign Currency Risk

While we operate primarily in the United States, we are exposed to foreign currency risk.  Our agreement with Astellas includes milestone and royalty payments which are denominated in Euros.  Our DIFICID API manufacturer, Biocon, is located in India and our manufacturer of DIFICID tablets, Patheon, is located in Canada.  Although we pay Biocon and Patheon in U.S. dollars changes in the Rupee and the Canadian dollar may result in price adjustments and affect our operating results.

In addition, certain transactions related to us and our subsidiary, OBI, are denominated primarily in Taiwan dollars.  We also recently established a subsidiary in Canada, Optimer Pharmaceuticals Canada, Inc. and we expect Optimer Canada’s transactions to be denominated primarily in Canadian dollars.  As a result, our financial results could be affected by factors such as changes in foreign currency exchange rates or weak economic conditions in foreign markets where we conduct business, including the impact of the existing conditions in the global financial markets in such countries and the impact on both the U.S. dollar , the New Taiwan dollar and the Canadian dollar.

We do not use derivative financial instruments for speculative purposes. We do not engage in exchange rate hedging or hold or issue foreign exchange contracts for trading purposes. Currently, we do not expect the impact of fluctuations in the relative fair value of other currencies to be material to our results of operations. However, we may, in the future, enter into  forward foreign currency exchange contracts to reduce foreign currency risk.

Item 4. Controls and Procedures

We maintain disclosure controls and procedures that are designed to ensure that information required to be disclosed in our reports under the Securities Exchange Act of 1934, as amended, or the Exchange Act, and the rules and regulations thereunder, is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms and that such information is accumulated and communicated to our management, including our chief executive officer and chief financial officer, as appropriate, to allow for timely decisions regarding required disclosure. In designing and evaluating our disclosure controls and procedures, management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives, and management is required to apply its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

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Evaluation of disclosure controls and procedures. As required by Exchange Act Rule 13a-15(b), we carried out an evaluation, under the supervision and with the participation of our management, including our chief executive officer and chief financial officer, of the effectiveness of the design and operation of our disclosure controls and procedures as of the end of the period covered by this report. Based on the foregoing, our chief executive officer and chief financial officer concluded that our disclosure controls and procedures were effective at the reasonable assurance level.

Changes in internal control over financial reporting. In connection with entering the Astellas collaboration agreement in February 2011 and the commercial launch of DIFICID, we have developed and will continue developing additional internal controls over our revenue recognition process.  In connection with the FDA approval of DIFICID in May 2011, we have developed and will continue developing internal controls over inventory processes. Except for the development of the additional internal controls over revenue recognition and inventory, there was no change in our internal control over financial reporting that occurred during the period covered by this report that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

PART II — OTHER INFORMATION

Item 1a. Risk Factors

The risk factors set forth below with an asterisk (*) next to the title are new risk factors or risk factors containing changes, including any material changes, from the risk factors previously disclosed in Item 1A of our Annual Report on Form 10-K for the year ended December 31, 2010, as filed with the SEC.

Risks Related to Our Business

Our success largely depends on our ability to successfully commercialize our only product, DIFICID.*

Our success depends on our ability to effectively commercialize our only product, DIFICID, which was approved by the FDA in May 2011, for the treatment of CDAD in adults 18 years of age and older.

We launched DIFICID in July 2011, and our ability to effectively commercialize and generate revenues from DIFICID will depend on several factors, including:

·                  our ability to create market demand for DIFICID through our own marketing and sales activities as well as through our co-promotion agreement with Cubist;

·                  our ability to train, deploy and support a qualified sales force;

·                  our ability to secure formulary approvals for DIFICID at a substantial number of targeted hospitals and long-term care facilities;

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·                  adequate coverage or reimbursement for DIFICID by government healthcare programs and third-party payors, including private health coverage insurers and health maintenance organizations;

·                  the performance of our third-party manufacturers and our ability to ensure that our supply chain for DIFICID efficiently and consistently delivers DIFICID to our customers;

·                  the ability to implement and maintain agreements with wholesalers and distributors on commercially reasonable terms; and

·                  our ability to maintain and defend our patent protection and regulatory exclusivity for DIFICID.

Any disruption in our ability to generate revenues from the sale of DIFICID or lack of success in its commercialization will have a substantial adverse impact on our results of operations.

The success of our efforts to commercialize DIFICID in the United States will be partially dependent on our co-promotion agreement with Cubist.*

Pursuant to our co-promotion agreement with Cubist, we engaged Cubist as our exclusive partner for the promotion of DIFICID in the United States. We have limited control over the amount and timing of resources that Cubist may devote to the co-promotion of DIFICID. If Cubist fails to adequately promote DIFICID, or if Cubist’s efforts are not effective for any other reason, our business may be negatively affected.  In particular, we are relying on our co-promotion agreement with Cubist to reach a broader segment of the CDAD market than we could otherwise reach on our own.  If Cubist is unsuccessful or the co-promotion agreement is terminated earlier than we expect, we may not be able to address these broader CDAD market segments, and the revenues we may generate from sales of DIFICID in the United States will be limited.

We are subject to a number of other risks associated with our dependence on our co-promotion agreement with Cubist, including:

·                  Cubist could fail to devote sufficient resources to the promotion of DIFICID, including by failing to maintain or train sufficient sales or medical affairs personnel to promote or provide information regarding DIFICID;

·                  Cubist may not comply with applicable regulatory guidelines with respect to the promotion of DIFICID, which could adversely impact sales of DIFICID in the United States;

·                  Cubist may not provide us with timely and accurate information regarding promotion and sales activities with respect to DIFICID, which could adversely impact our ability to manage our own inventory of DIFICID in the United States, as well as our ability to generate accurate financial forecasts;

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·                  we and Cubist may not be successful in coordinating our respective sales and promotion activities under the co-promotion agreement, which could lead to inefficiencies, the failure to maximize DIFICID sales in the Unites States, and/or disagreements between us and Cubist; or

·                  business combinations or significant changes in Cubist’s business strategy, including the acquisition or development by Cubist of other products, may adversely affect Cubist’s ability or willingness to perform its obligations under our co-promotion agreement.

Our co-promotion agreement with Cubist is subject to early termination, including through Cubist’s right to terminate if we experience certain supply failures in relation to the demand for DIFICID in the United States or if we are acquired by certain types of entities, including competitors of Cubist.  If the agreement is terminated early, we may not be able to find another partner to co-promote DIFICID in the United States on acceptable terms, or at all, and we may be unable to sufficiently promote and commercialize DIFICID in the United States on our own.

We are dependent on our collaboration agreement with Astellas to commercialize and further develop DIFICID in the Astellas territory.  The failure to maintain this agreement or the failure of Astellas to perform its obligations under this agreement, could negatively impact our business.*

Pursuant to the terms of our collaboration agreement with Astellas, we granted to Astellas exclusive rights to develop and commercialize DIFICID in the Astellas territory, and pursuant to the terms of our supply agreement with Astellas, we are obligated to supply to Astellas all of its requirements of DIFICID for such development and commercialization activities.  Consequently, our ability to generate any revenues from DIFICID in the Astellas territory depends on Astellas’ ability to obtain regulatory approvals for and successfully commercialize DIFICID in the Astellas territory.  We have limited control over the amount and timing of resources that Astellas will dedicate to these efforts.

We are subject to a number of other risks associated with our dependence on our collaboration agreement with Astellas, including:

·                  Astellas may not comply with applicable regulatory guidelines with respect to developing or commercializing DIFICID, which could adversely impact sales or future development of DIFICID in the Astellas territory;

·                  we and Astellas could disagree as to future development plans and Astellas may delay future clinical trials or stop a future clinical trial;

·                  there may be disputes between us and Astellas, including disagreements regarding the collaboration agreement, that may result in (1) the delay of or failure to achieve regulatory and commercial objectives that would result in milestone or royalty payments, (2) the delay or termination of any future development or commercialization of DIFICID, and/or (3) costly litigation or arbitration that diverts our management’s attention and resources;

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·                  because the milestone and royalty payments in the collaboration agreement are stated in terms of Euros but paid to us in U.S. Dollars, the amounts of any milestone or royalty payments that may be paid to us under the collaboration agreement could be less than what we expect, depending on the applicable exchange rate at the time of such payments;

·                  Astellas may not provide us with timely and accurate information regarding sales and marketing activities and supply forecasts, which could adversely impact our ability to comply with our supply obligations to Astellas and manage our own inventory of DIFICID, as well as our ability to generate accurate financial forecasts;

·                  business combinations or significant changes in Astellas’ business strategy may adversely affect Astellas’ ability or willingness to perform its obligations under our collaboration and supply agreements;

·                  Astellas may not properly maintain or defend our intellectual property rights in the Astellas territory or may use our proprietary information in such a way as to invite litigation that could jeopardize or invalidate our intellectual property rights or expose us to potential litigation;

·                  the royalties we are eligible to receive from Astellas may be reduced or eliminated based upon Astellas’ and our ability to maintain or defend our intellectual property rights and the presence of generic competitors in the Astellas territory;

·                  limitations under the agreement on our or an acquiror’s ability to maintain or pursue development or commercialization of products that are competitive with DIFICID could deter a potential acquisition of us that our stockholders may otherwise view as beneficial; and

·                  if Astellas is unsuccessful in obtaining regulatory approvals for or commercializing DIFICID in the Astellas territory, we may not receive any additional milestone or royalty payments under the collaboration agreement and our business prospects and financial results may be materially harmed.

The collaboration and supply agreements are subject to early termination, including through Astellas’ right to terminate without cause upon advance notice to us.  If the agreements are terminated early, we may not be able to find another collaborator for the commercialization and further development of DIFICID in the Astellas territory on acceptable terms, or at all, and we may be unable to pursue continued commercialization or development of DIFICID in the Astellas territory on our own.

We may enter into additional agreements for the commercialization of DIFICID or other of our drug candidates, and may be similarly dependent on the performance of third parties with similar risk.

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Other than our collaboration agreement with Astellas, we may not be able to enter into acceptable agreements to commercialize DIFICID outside of the United States or if, needed, adequately build our own marketing and sales capabilities.*

We intend to pursue the development of and potentially commercialize DIFICID outside of the United States through collaboration arrangements with third parties, such as our collaboration with Astellas, or independently.  We may be unable to enter into additional collaboration arrangements in international markets outside of the Astellas territory.  In addition, there can be no guarantee that Astellas or any other parties that we may enter into collaboration arrangements with will be successful or result in more revenues than we could obtain by marketing DIFICID on our own. If we are unable to enter into additional collaboration arrangements for our products or develop an effective international sales force, our ability to generate product revenues would be limited, which would adversely affect our business, financial condition, results of operations and prospects. If we are unable to enter into such collaboration arrangements for development of DIFICID in countries outside of the United States and outside of the Astellas territory, or if we otherwise decide to market DIFICID ourselves in these countries, we will need to develop our own marketing and sales force to market DIFICID in these territories to hospital-based and long-term care physicians.  These efforts, including our anticipated efforts in Canada through our recently established subsidiary, Optimer Canada, may not be successful as we have limited relationships among such hospital-based and long-term care physicians and may not currently have sufficient funds to develop an adequate sales force in each of these regions.  There is no guarantee that we will be able to develop an effective international sales force to successfully commercialize our products in these international markets.  If we cannot commercialize DIFICID, either through a collaboration or independently, in any territory that represents a significant market opportunity, our ability to achieve and sustain profitability will be substantially limited.

We have incurred significant operating losses since inception and anticipate that we will incur continued losses for the foreseeable future.*

We have experienced significant operating losses since our inception in 1998.  As of September 30, 2011, we had an accumulated deficit of approximately $228.3 million.  We have generated minimal revenues from product sales to date and we expect our expenses to increase substantially in the near term as we execute the commercial launch of DIFICID due to, among other things, increases to our headcount and on-going payments to Cubist pursuant to our co-promotion agreement,  and as we pursue additional research and development activities, including potential additional indications for DIFICID. We have funded our operations through September 30, 2011 from the sale of approximately $333.8 million of our securities and through payments received under collaborations with partners or government grants. Because of the numerous risks and uncertainties associated with commercializing DIFICID and with developing, obtaining regulatory approval for and commercializing any future product candidates, we are unable to predict the extent of any future losses.  We or our collaborators may never successfully commercialize our product candidates, including DIFICID outside of the United States, and thus we may never have any significant future revenues or achieve and sustain profitability.

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If we and Cubist are unable to effectively train and equip our respective sales forces, our ability to successfully commercialize DIFICID in the U.S. will be harmed.*

As DIFICID is a newly marketed drug, none of the members of our or Cubist’s sales forces had ever promoted DIFICID prior to its launch in July 2011. As a result, we and Cubist are required to expend significant time and resources to train our respective sales forces to be credible and persuasive in convincing physicians, pharmacists, long-term care facilities and hospitals to use DIFICID. In addition, we and Cubist also must train our respective sales forces to ensure that a consistent and appropriate message about DIFICID is being delivered to our potential customers. We must also effectively collaborate and coordinate with Cubist sales force representatives in co-promoting DIFICID, including training efforts.  If we or Cubist are unable to effectively train our respective sales forces and equip them with effective materials, including medical and sales literature to help them inform and educate potential customers about the benefits of DIFICID and its proper administration, our efforts to successfully commercialize DIFICID could be put in jeopardy, which could have a material adverse effect on our financial condition, stock price and operations.

The commercial success of DIFICID and any other products we develop or acquire will depend upon attaining significant market acceptance among physicians, hospitals, patients, healthcare payors and the medical community.*

Even after approved by the appropriate regulatory authorities for marketing and sale, physicians may not prescribe any of our products, which would prevent us from generating revenues or becoming profitable.  Market acceptance of our products by physicians, hospitals, patients and healthcare payors will generally depend on a number of factors, many of which are beyond our control, including:

·                  timing of market introduction of our products as well as of competitive drugs;

·                  the clinical indications for which the product is approved;

·                  acceptance by physicians and patients of each product as a safe and effective treatment;

·                  perceived advantages over alternative treatments;

·                  the cost of treatment in relation to alternative treatments, including numerous generic antibiotics;

·                  the extent to which the product is approved for inclusion on formularies of hospitals and managed care organizations;

·                  the extent to which bacteria develops resistance to the product, thereby limiting its efficacy in treating or managing infections;

·                  whether the product is designated under physician treatment guidelines as a first-line therapy or as a second- or third-line therapy for particular infections;

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·                  the availability of adequate reimbursement by third parties, such as insurance companies and other healthcare payors;

·                  limitations or warnings contained in a product’s FDA-approved labeling;

·                  relative convenience and ease of administration; and

prevalence and severity of adverse side effects.

With respect to DIFICID specifically, successful commercialization will depend on whether and to what extent physicians, pharmacists, long-term care facilities and hospital pharmacies, over whom we have no control, determine to utilize DIFICID. The sale of DIFICID to each hospital is to a large extent dependent upon the addition of DIFICID to that hospital’s list of approved drugs, or formulary list, by the hospital’s Pharmacies and Therapeutics, or P&T, committee. A hospital’s P&T committee typically governs all matters pertaining to the use of medications within the institution, including review of medication formulary data and recommendations for the appropriate use of drugs within the institution to the medical staff. The frequency of P&T committee meetings at various hospitals varies considerably, and P&T committees often require additional information to aide in their decision-making process, so we may experience substantial delays in obtaining formulary approvals. Additionally, hospital pharmacists may be concerned that the cost of DIFICID will adversely impact their overall pharmacy budgets, which could cause pharmacists to resist adding DIFICID to the formulary, or to implement restrictions on the usage of the drug in order to control costs. We cannot guarantee that we will be successful in getting additional approvals from P&T committees in a timely manner or at all, and the failure to do so will limit our ability to optimize hospital sales of DIFICID.

Even if we obtain hospital formulary approval for DIFICID, physicians must still prescribe DIFICID for its commercialization to be successful. Because DIFICID is a new drug with a very limited track record of sales in the U.S., any inability to timely supply DIFICID to our customers, or any unexpected side effects that arise from the use of the drug, particularly early in the product launch, may lead physicians to not accept DIFICID as a viable treatment alternative.

Even after receipt of regulatory approval from the FDA, DIFICID is, and any other products we may develop or acquire in the future will be, subject to substantial, ongoing regulatory requirements.*

DIFICID is, and any future approved products will be, subject to ongoing FDA requirements with respect to manufacturing, labeling, packaging, storage, distribution, advertising, promotion, record-keeping and submission of safety and other post-market information on the drug. The FDA has the authority to regulate the claims we make in marketing any products, including DIFICID, to ensure that such claims are true, not misleading, supported by scientific evidence and consistent with the approved label for the drug. In addition, the discovery of previously unknown problems with DIFICID or any future approved product, such as adverse events of unanticipated severity or frequency, or problems with the facilities where active pharmaceutical ingredient, or API, or final drug product is manufactured, may result in the imposition of additional restrictions, including requiring us to reformulate the product, conduct additional clinical trials, make changes in the labeling of the product or withdraw the product from the market.

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The FDA or foreign regulatory authorities may also impose ongoing requirements for potentially costly post-approval studies for any approved product. For example, as a condition of the FDA’s approval of DIFICID, we are required to conduct a microbiological surveillance program to identify the potential for decreased susceptibility of C. difficile to DIFICID, as well as two post-marketing studies in pediatric patients. We also plan to conduct a randomized trial to evaluate the efficacy of DIFICID in the treatment of patients with multiple CDAD recurrences.  Depending on the outcome of the studies, we may be unable to expand the indications for DIFICID or we may be required to include specific warnings or limitations on dosing this product, which could negatively impact our sales of DIFICID.

We have implemented a comprehensive compliance program and related infrastructure, but we cannot provide absolute assurance that we are or will be in compliance with all potentially applicable laws and regulations. If our operations in relation to DIFICID or any future approved product fail to comply with applicable regulatory requirements, the FDA or other regulatory agencies may:

·                  issue warning letters or untitled letters;

·                  impose consent decrees, which may include the imposition of various fines, reimbursement for inspection costs, due dates for specific actions and penalties for noncompliance;

·                  impose fines or other civil or criminal penalties;

·                  suspend regulatory approval;

·                  suspend any ongoing clinical trials;

·                  refuse to approve pending applications or supplements to approved applications filed by us;

·                  impose restrictions on operations, including costly new manufacturing requirements;

·                  exclude us from participating in U.S. federal healthcare programs, including Medicaid or Medicare; or

·                  seize or detain products or require a product recall.

Any of these regulatory actions due to our failure to comply with post-approval requirements could damage our reputation, limit our ability to market our products and adversely affect our operating results.  In addition, the failure of our current or future collaborators to comply with these regulations and similar regulations in foreign jurisdictions would limit our ability to fully commercialize DIFICID and any other product we may develop or acquire in the future.

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We must comply with federal and state “fraud and abuse” laws, and, if we are unable to fully comply with such laws, we could face substantial penalties, which may adversely affect our business, financial condition and results of operations.*

In the United States, in addition to FDA restrictions, we are subject to healthcare fraud and abuse regulation and enforcement by both the federal government and the states in which we conduct our business. The laws that may affect our ability to operate include:

·                  the federal healthcare programs’ Anti-Kickback Law, which prohibits, among other things, persons from knowingly and willfully soliciting, receiving, offering or paying remuneration, directly or indirectly, in exchange for or to induce either the referral of an individual for, or the purchase, order or recommendation of, any good or service for which payment may be made under federal healthcare programs such as the Medicare and Medicaid programs;

·                  federal false claims laws which prohibit, among other things, individuals or entities from knowingly presenting, or causing to be presented, claims for payment from Medicare, Medicaid, or other third-party payors that are false or fraudulent;

·                  the federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, which created federal criminal laws that prohibit executing a scheme to defraud any health care benefit program or making false statements relating to health care matters;

·                  federal “sunshine” laws that require transparency regarding financial arrangements with health care providers, such as the reporting and disclosure requirements imposed by the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Affordability Reconciliation Act, or collectively, PPACA, on drug manufacturers regarding any “transfer of value” made or distributed to prescribers and other health care providers; and

·                  state law equivalents of each of the above federal laws, such as anti-kickback and false claims laws which may apply to items or services reimbursed by any third-party payor, including commercial insurers.

Some states, such as California, Massachusetts and Vermont, mandate implementation of comprehensive compliance programs to ensure compliance with these laws.

The risk of our being found in violation of these laws is increased by the fact that many of them have not been fully interpreted by applicable regulatory authorities or the courts, and their provisions are open to a variety of interpretations. Although there are a number of statutory exemptions and regulatory safe harbors protecting certain common activities from prosecution or other regulatory sanctions, the exemptions and safe harbors are drawn narrowly, and practices that involve remuneration intended to induce prescribing, purchases or recommendations may be subject to scrutiny if they do not qualify for an exemption or safe harbor. Recently, several pharmaceutical and other healthcare companies have been prosecuted under these laws for

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allegedly inflating drug prices they report to pricing services, which in turn are used by the government to set Medicare and Medicaid reimbursement rates, and for allegedly providing free product to customers with the expectation that the customers would bill federal programs for the product. In addition, certain marketing practices, including off-label promotion, may also violate false claims laws.

Recent healthcare reform legislation has also strengthened these laws.  For example, the recently enacted PPACA, among other things, amended the intent requirement of the federal anti-kickback and criminal health care fraud statutes such that a person or entity no longer needs to have actual knowledge of this statute or specific intent to violate it.  In addition, PPACA provides that the government may assert that a claim including items or services resulting from a violation of the federal anti-kickback statute constitutes a false or fraudulent claim for purposes of the false claims statutes.  We also expect there will continue to be federal and state laws and/or regulations, proposed and implemented, that could impact our operations and business.  The extent to which future legislation or regulations, if any, relating to healthcare fraud abuse laws and/or enforcement, may be enacted or what effect such legislation or regulation would have on our business remains uncertain.

Violations of these laws are punishable by criminal and civil sanctions, including, in some instances, exclusion from participation in federal and state healthcare programs, including Medicare and Medicaid, and the curtailment or restructuring of operations.  We believe that our operations are in material compliance with these laws and we recently increased our compliance resources in connection with the commercial launch of DIFICID.  However, because of the far-reaching nature of these laws, there can be no assurance that we will not be required to alter one or more of our practices to be in compliance with these laws.  In addition, there can be no assurance that the occurrence of one or more violations of these laws or regulations would not result in a material adverse effect on our financial condition and results of operations.

Our product sales depend on adequate coverage and reimbursement from third-party payers.*

Our and our collaborators’ sales of DIFICID are, and sales of any future approved products will be, dependent on the availability and extent of coverage and reimbursement from third-party payers, including government healthcare programs and private insurance plans. We and our collaborators rely in large part on the reimbursement coverage by federal and state sponsored government programs such as Medicare and Medicaid in the United States, which are increasingly challenging prices charged and the cost-effectiveness of medical products.  These practices maybe further exacerbated by future healthcare reform measures.  In addition, many healthcare providers, such as hospitals, receive a fixed reimbursement amount per procedure or other treatment therapy based on a prospective payment system, and these amounts are not necessarily based on the actual costs incurred.  As a result, these healthcare providers may be inclined to choose the least expensive therapies.  We cannot guarantee that our potential customers will find the reimbursement amounts sufficient to cover the costs of our products, including DIFICID.

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We have licensed rights to develop and commercialize DIFICID in Europe and certain other countries to Astellas.  In the event we or our collaborators, including Astellas, seek approvals to market DIFICID in other non-U.S. territories, we or our collaborators including Astellas, will need to work with the government-sponsored healthcare entities in Europe and each other foreign country, as applicable, that are the primary payers of healthcare costs in such regions.  Certain government payers may regulate prices, reimbursement levels and/or access to DIFICID or any future products to control costs or to affect levels of use of the product.

We cannot predict the availability or level of coverage and reimbursement for DIFICID or any future approved product.  If third-party coverage and reimbursement is not available or is available only to limited levels, we may not be able to commercialize DIFICID or any other products successfully or at all, which would materially harm our business and prospects.

Regulatory approval for any approved product is limited by the FDA to those specific indications and conditions for which clinical safety and efficacy have been demonstrated as listed in the approved labeling.*

Any regulatory approval is limited to those specific diseases and indications for which a product is deemed to be safe and effective by the FDA. In addition to the FDA approval required for new formulations, any new indication for an approved product also requires FDA approval.

While physicians may choose to prescribe drugs for uses that are not described in the product’s labeling and for uses that differ from those tested in clinical studies and approved by the regulatory authorities, our ability to promote the products is limited to those indications that are specifically approved by the FDA. Regulatory authorities in the U.S. generally do not regulate the behavior of physicians in their choice of treatments, and such off-label uses by healthcare professionals are common. Regulatory authorities do, however, restrict communications by pharmaceutical companies on the subject of off-label use. If we are not able to obtain FDA approval for any desired future indications for DIFICID or any future approved products, our ability to market and sell such products will be limited and our business may be adversely affected.

If we or our collaborators fail to gain and/or maintain marketing approvals from regulatory authorities in international markets for DIFICID and any future product candidates for which we have or license rights in international markets, our market opportunities will be limited.*

Our and our collaborators’ ability to sell our product candidates outside of the United States is subject to foreign regulatory requirements governing clinical trials and marketing approval.  Even if the FDA grants marketing approval for a product candidate, comparable regulatory authorities of foreign countries must also approve the marketing of the product candidate in those countries.    Regulatory requirements can vary widely from country to country and could delay the introduction of our products in those countries.  Clinical trials conducted in one country may not be accepted by regulatory authorities in other countries, and regulatory approval in one country does not guarantee regulatory approval will be obtained in any other country.  In addition, our or our collaborators’ failure to obtain regulatory approval in any country may delay

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or have negative effects on the process for regulatory approval in others. We could experience significant delays and difficulties and incur significant costs in obtaining foreign regulatory approvals in the territories for which we retain commercialization rights.

None of our product candidates is approved for sale in any international market for which we have or have licensed rights. If we or our collaborators fail to comply with regulatory requirements with respect to our product candidates in international markets or to obtain and maintain required approvals, our market opportunities and ability to generate revenues will be diminished, which would significantly harm our business, results of operations and prospects. For example, if Astellas is unable to obtain approvals to market DIFICID in the Astellas territory, particularly in the European Union, our ability to recognize future milestone and royalty payments under our agreement with Astellas will be substantially limited.  Moreover, while the Committee for Medicinal Products for Human Use, or CHMP, of the European Medicines Agency, or EMA, recently adopted a positive opinion for DIFICLIR (fidaxomicin) tablets, there is no guarantee that the EMA will ultimately follow the opinion of the CHMP when making its final determination on the DIFICLIR marketing authorization application, or MAA.

If product liability lawsuits are brought against us, we may incur substantial liabilities and may be required to limit commercialization of our products.*

We face an inherent risk of product liability lawsuits related to the testing of our product candidates, and face an even greater risk related to the sale of commercial products, such as DIFICID.  An individual may bring a liability claim against us if one of our products or product candidates causes, or merely appears to have caused, an injury.  If we cannot successfully defend ourselves against a product liability claim, we may incur substantial liabilities.  Regardless of merit or eventual outcome, product liability claims may result in:

·                  significant litigation costs;

·                  substantial monetary awards to or costly settlement with patients;

·                  product recalls and/or an inability to continue marketing our products;

·                  decreased demand for our product;

·                  injury to our reputation;

·                  termination of clinical trial sites or entire clinical trial programs;

·                  withdrawal of clinical trial participants;

·                  loss of revenues; and

·                  the inability to commercialize our product candidates.

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Our ability to market products is dependent upon physician and patient perceptions of us and the safety and quality of our products.  We could be adversely affected if we or our products and product candidates are subject to negative publicity.  We could also be adversely affected if any of our products or product candidates or any similar products distributed by other companies prove to be, or are asserted to be, harmful to patients.  Also, because of our dependence upon physician and patient perceptions, any adverse publicity associated with illness or other adverse effects resulting from patients’ use or misuse of our products or any similar products distributed by other companies could have a material adverse impact on our results of operations.

We have product liability insurance that covers our commercial product up to a $10.0 million annual aggregate limit as well as global clinical trial liability insurance that covers our clinical trials up to a $10.0 million annual aggregate limit.  Our current or future insurance coverage may prove insufficient to cover any liability claims brought against us.  Because of the increasing costs of insurance coverage, we may not be able to maintain insurance coverage at a reasonable cost or obtain insurance coverage that will be adequate to satisfy any liability that may arise.

If we fail to obtain additional financing, we may be unable to commercialize DIFICID and develop and commercialize other product candidates, or continue our other research and development programs.*

We may require additional capital to fully commercialize DIFICID and any future products for which we obtain regulatory approval or acquire or in-license.  We cannot be certain that additional funding will be available on acceptable terms, or at all.  To the extent that we raise additional funds by issuing equity securities, our stockholders may experience significant dilution.  Any debt financing, if available, may require us to pledge our assets as collateral or involve restrictive covenants, such as limitations on our ability to incur additional indebtedness, limitations on our ability to acquire or license intellectual property rights and other operating restrictions that could negatively impact our ability to conduct our business.  If we are unable to raise additional capital when required or on acceptable terms, we may have to significantly scale back our commercialization activities for DIFICID in the United States or significantly delay, scale back or discontinue the development of one or more of our product candidates or research and development initiatives.  We also could be required to:

·                  seek collaborators for one or more of our current or future products or product candidates at an earlier stage than otherwise would be desirable or on terms that are less favorable than might otherwise be available; or

·                  relinquish or license on unfavorable terms our rights to technologies or product candidates that we otherwise would seek to develop or commercialize ourselves.

Any of the above events could significantly harm our business and prospects and could cause our stock price to decline.

To the extent we require addition resources to successfully commercialize DIFICID, and we are unable to raise additional capital or are unable to effectively collaborate with additional partners for the commercialization of DIFICID, we will not generate significant revenues from sales of this product and our business will be materially harmed.

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If we fail to attract and retain senior management and key scientific personnel, we may be unable to successfully develop or commercialize our product candidates.*

Our success depends in part on our continued ability to attract, retain and motivate highly qualified management, sales and marketing, clinical and scientific personnel and on our ability to develop and maintain important relationships with leading academic institutions, clinicians and scientists.  We are highly dependent on our chief executive officer, and the other principal members of our executive and scientific teams. The unexpected loss of the service of any of these persons may significantly delay or prevent the achievement of research, development, commercialization and other business objectives.  Replacing key employees may be difficult and costly and may take an extended period of time because of the limited number of individuals in our industry with the breadth of skills and experience required to develop and commercialize pharmaceutical products successfully.  We do not maintain “key person” insurance policies on the lives of these individuals or the lives of any of our other employees.  With the exception of Mr. Lichtinger, we employ these individuals on an at-will basis and their employment can be terminated by us or them at any time, for any reason and with or without notice.

We will need to hire additional personnel as we expand our commercial activities.  We may not be able to attract or retain qualified management, sales and marketing and scientific personnel on acceptable terms in the future due to the intense competition for qualified personnel among biotechnology, pharmaceutical and other businesses, particularly in the San Diego, California and New Jersey areas.  If we are not able to attract and retain the necessary personnel to accomplish our business objectives, we may experience constraints that will impede significantly the achievement of our commercialization and research and development objectives, our ability to raise additional capital and our ability to implement our business strategy.  In particular, if we lose any members of our senior management team, we may not be able to find suitable replacements, and our business and prospects may be harmed as a result.

We recently established a sales and marketing organization and have little experience as a company in marketing drug products.*

Our strategy is to build a fully-integrated U.S.-focused biopharmaceutical company to successfully execute the commercial launch of DIFICID in the U.S. market.  Although we have engaged Cubist as our exclusive partner to co-promote DIFICID in the United States, we have very limited experience commercializing pharmaceutical products on our own. In order to commercialize products, in addition to our engagement of Cubist as our exclusive co-promotion partner for DIFICID in the United States, we have established our own marketing, sales, distribution, pharmacovigilence, managerial and other non-technical capabilities. We established the commercial organization primarily in New Jersey, and our bicoastal organizational structure could create management challenges.  The establishment and development of our own sales force to market DIFICID has been and will continue to be expensive and time consuming and could delay any product launch, and we cannot be certain that we will be able to successfully maintain this capability or successfully adapt it to commercialize and future products we may develop or

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acquire. Although we have engaged Cubist to assist in the promotion of DIFICID in the United States, our agreement with Cubist could terminate early, and our commercial presence may not be sufficient to adequately market DIFICID in the United States on our own. We also compete with other pharmaceutical and biotechnology companies to recruit, hire, train and retain marketing and sales personnel. To the extent we rely on third parties to commercialize our products, if any, we may receive less revenues than if we commercialized these products ourselves. In addition, we may have little or no control over the sales efforts of any third parties involved in commercializing our products, including those of Astellas in the Astellas territory and Cubist in the United States. In the event we are unable to further develop and maintain our own marketing and sales capabilities or collaborate with a third-party marketing and sales organization, we would not be able to fully commercialize any product, including DIFICID, which would negatively impact our ability to generate product revenues.

We substantially increased the size of our organization, and we may experience difficulties in managing growth.*

We are a relatively small company with 271 employees as of October 31, 2011.  The commercial launch of DIFICID required us to expand our managerial, operational, marketing, sales, financial and other resources.  Our management, personnel, systems and facilities currently in place may not be adequate to support this recent growth, and we may not be able to retain or recruit qualified personnel in the future due to competition for personnel among pharmaceutical businesses, and the failure to do so could have a significant negative impact on our future product revenue and business results.  To effectively manage our operations growth and various projects, we must:

·                  effectively train and manage a significant number of new employees, in particular our sales force, who have no prior experience with our company or DIFICID, and establish appropriate systems, policies and infrastructure to support our commercial organization;

·                  ensure that our consultants and other service providers successfully carry out their contractual obligations, provide high quality results, and meet expected deadlines;

·                  continue to carry out our own contractual obligations to our licensors and other third parties; and

·                  continue to improve our operational, financial and management controls, reporting systems and procedures.

We may not be able to implement these tasks on a larger scale, and accordingly, may not achieve our development and commercialization goals.  Our failure to accomplish any of these goals could harm our financial results and prospects.

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We currently depend, and will in the future continue to depend, on third parties to manufacture our products and product candidates, including DIFICID.  If these manufacturers fail to provide us and our collaborators with adequate supplies of clinical trial materials and commercial product or fail to comply with the requirements of regulatory authorities, we may be unable to develop or commercialize our products.*

We have outsourced all manufacturing of supplies of our products and product candidates to third parties.  We seek to establish long-term supply arrangements with third-party contract manufacturers. For example, in May 2010, we entered into a long-term supply agreement with Biocon for the commercial manufacturing of the API, for DIFICID and in June 2011, we entered into a manufacturing services agreement with Patheon to manufacture and supply certain fidaxomicin products, including DIFICID.  We intend to continue outsourcing the manufacture of our products and product candidates to third parties for any future clinical trials and large-scale commercialization of any product candidates that receive regulatory approval and become commercial drugs, such as DIFICID.

Our ability and that of our collaborators to develop and commercialize DIFICID and any other product candidates will depend in part on our ability and that of our collaborators to arrange for third parties to manufacture our products at a competitive cost, in accordance with strictly enforced regulatory requirements and in sufficient quantities for regulatory approval, commercialization and any future clinical trials.  Third-party manufacturers that we select to manufacture our product candidates for clinical testing or on a commercial scale may encounter difficulties with the small- and large-scale formulation and manufacturing processes required for such manufacture.  Further, development of large-scale manufacturing processes will require additional validation studies, which the FDA must review and approve.  Difficulties in establishing these required manufacturing processes could result in delays in clinical trials, regulatory submissions and approvals, or commercialization of our product candidates.

While we work closely with our current suppliers to try to ensure continuity of supply while maintaining high quality and reliability, we cannot guarantee that these efforts will be successful.  Even if we are able to establish additional or replacement manufacturers, identifying these sources and entering into definitive supply agreements and obtaining regulatory approvals may involve a substantial amount of time and cost and such supply arrangements may not be available on acceptable economic terms.  A reduction or interruption in our supply of DIFICID API or drug product from our current suppliers, and an inability to develop alternative sources for such supply, could adversely affect our ability to obtain DIFICID in a timely or cost effective manner to maximize product sales, and could result in a breach of our supply agreement with Astellas or our co-promotion agreement with Cubist, which could result in either or both of those parties terminating their respective agreements with us.

In addition, we, our collaborators and other third-party manufacturers of our products must comply with strictly enforced current good manufacturing practices, or cGMP, requirements enforced by the FDA through its facilities inspection program.  These requirements include quality control, quality assurance and the maintenance of records and documentation.  We currently rely on Biocon to manufacture DIFICID API and rely on Patheon to manufacture the drug product supplies.  As such, Biocon and Patheon will be subject to ongoing periodic unannounced inspections by the FDA and other agencies for compliance with current cGMP, and similar foreign standards. The manufacturing facilities of Biocon and Patheon have been

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inspected and approved by the FDA for other companies’ drug products; however, none of Biocon’s nor Patheon’s facilities have been inspected by the FDA for the manufacture of our drug supplies.    We or other third-party manufacturers of our products may be unable to comply with cGMP requirements and with other FDA, state, local and foreign regulatory requirements.  We and our collaborators have little control over third-party manufacturers’ compliance with these regulations and standards.  A failure to comply with these requirements by our third-party manufacturers, including Biocon and Patheon could result in the issuance of untitled letters and/or warning letters from authorities, as well as sanctions being imposed on us, including fines and civil penalties, suspension of production, suspension or delay in product approval, product seizure or recall or withdrawal of product approval.  In addition, we have no control over these manufacturers’ ability to maintain adequate quality control, quality assurance and qualified personnel.  If the safety of any quantities supplied by third parties is compromised due to their failure to adhere to applicable laws or for other reasons, we and our collaborators may not be able to obtain or maintain regulatory approval for or successfully commercialize one or more of our product, which would significantly harm our business and prospects.

If our product candidates are unable to compete effectively with branded and generic antibiotics, our commercial opportunity would be reduced or eliminated.*

Our products and product candidates compete or will compete against both branded and generic antibiotic therapies, such as branded Vancocin Pulvules, generic metronidazole and oral vancomycin with respect to DIFICID.  In addition, we anticipate that DIFICID will compete with other antibiotic and anti-infective product candidates currently in development for the treatment of CDAD. For example, Cubist recently announced its intention to proceed with a Phase 3 clinical trial for its compounds, CB-183,315, as a potential treatment for CDAD. Many of these products have been or will be developed and marketed by major pharmaceutical companies, who have significantly greater financial resources and expertise in research and development, pre-clinical testing, conducting clinical trials, obtaining regulatory approvals, manufacturing and marketing approved products than we do.  As a result, these companies may obtain regulatory approval more rapidly than we are able to and may be more effective in selling and marketing their products as well.  Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large, established pharmaceutical or other companies.

DIFICID currently faces, and we anticipate it will continue to face, increasing competition in the form of generic versions of branded products of competitors that will lose their patent exclusivity.  For example, DIFICID currently faces steep competition from an inexpensive generic form of metronidazole.  If approved in Europe, DIFICID will immediately face generic oral vancomycin competition and in the future may face competition from generic oral vancomycin in the United States as well.  In addition, our internal market research suggests that there is increasing use of oral reconstituted intravenous vancomycin “slurry” in the hospital setting.  Generic antibiotic therapies typically are sold at lower prices than branded antibiotics and are generally preferred by managed care providers of health services.  For example, because metronidazole and generic vancomycin “slurry” are available at such a low price, we believe it may be difficult to sell DIFICID as a first-line therapy for the treatment of CDAD other than in certain limited circumstances, such as in patients at high risk of recurrence.  If we or our

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collaborators are unable to demonstrate to physicians and patients that, based on experience, clinical data, side-effect profiles and other factors, our products are preferable to these generic antibiotic therapies, we may never generate meaningful product revenues.  In addition, many antibiotics experience bacterial resistance over time because of their continued use.  There can be no guarantee that bacteria would not develop resistance to DIFICID or any of our other product candidates.  Our commercial opportunity would also be reduced or eliminated if our competitors develop and commercialize generic or branded antibiotics that are safer, more effective, have lower recurrence rates, have fewer side effects or are less expensive than our product candidates.

If we fail to develop and commercialize other products or product candidates, we may be unable to grow our business.*

A key element of our strategy is to commercialize a portfolio of innovative hospital specialty products in addition to DIFICID.  As a significant part of our growth strategy, we intend to develop and commercialize, independently and/or through collaboration partners, additional products and product candidates through our discovery research program using our proprietary technology, including OPopS.  The success of this strategy depends upon our ability to identify, select and acquire pharmaceutical product candidates and products that fit into our development plans on terms that are acceptable to us. To supplement this strategy, we may also obtain rights to additional product candidates from third parties through acquisition or in-licensing transactions.

Any product candidate we identify or to which we acquire rights will likely require additional development efforts prior to commercial sale, including pre-clinical studies, extensive clinical testing and approval by the FDA and applicable foreign regulatory authorities.  All product candidates are prone to the risks of failure that are inherent in pharmaceutical product development, including the possibility that the product candidate will not be shown to be sufficiently safe and/or effective for approval by regulatory authorities.  In addition, we cannot assure you that any such products that are approved will be manufactured or produced economically, successfully commercialized or widely accepted in the marketplace or be more effective than other commercially available alternatives.

A significant portion of the research that we are conducting involves new and unproven technologies.  Research programs to identify new disease targets and product candidates require substantial technical, financial and human resources whether or not we ultimately identify any candidates.  Our research programs may initially show promise in identifying potential product candidates, yet fail to yield product candidates for clinical development. If we are unable to develop suitable potential product candidates through internal research programs or by obtaining rights to novel therapeutics from third parties, our business and prospects will suffer.

Our focus on drug discovery and development using our technology platform, including our patented proprietary OPopS drug discovery platform, is novel and unique.  As a result, we cannot be certain that our product candidates will produce commercially viable drugs that safely and effectively treat infectious diseases or other diseases.  To date, our technology platform has yielded only a small number of anti-infective product candidates.  In addition, we do not have significant clinical data with respect to any of these potential product candidates.  Even if we or

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