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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

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

For the quarterly period ended June 30, 2015

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:  001-33277

SYNTA PHARMACEUTICALS CORP.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (781) 274-8200

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 Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) 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.  (Check one):

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

As of August 3, 2015, the registrant had 136,442,378 shares of common stock outstanding.

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SYNTA PHARMACEUTICALS CORP.

INDEX TO FORM 10-Q

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PART I - FINANCIAL INFORMATION

Item 1.  Financial Statements.

SYNTA PHARMACEUTICALS CORP.

Condensed Consolidated Balance Sheets

(in thousands, except share and per share amounts)

(unaudited)

See accompanying notes to consolidated financial statements.

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SYNTA PHARMACEUTICALS CORP.

Condensed Consolidated Statements of Operations

(in thousands, except share and per share amounts)

(unaudited)

See accompanying notes to condensed consolidated financial statements.

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SYNTA PHARMACEUTICALS CORP.

Condensed Consolidated Statements of Comprehensive Loss

(in thousands)

(unaudited)

See accompanying notes to condensed consolidated financial statements.

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SYNTA PHARMACEUTICALS CORP.

Condensed Consolidated Statements of Cash Flows

(in thousands)

(unaudited)

See accompanying notes to condensed consolidated financial statements.

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SYNTA PHARMACEUTICALS CORP.

Notes to Condensed Consolidated Financial Statements

(unaudited)

(1) Nature of Business

Synta Pharmaceuticals Corp. (the Company) was incorporated in March 2000 and commenced operations in July 2001. The Company is an innovative, agile biopharmaceutical company focused on research, development and commercialization of novel oncology medicines that have the potential to change the lives of cancer patients.

The Company is subject to risks common to emerging companies in the drug development and pharmaceutical industry including, but not limited to, uncertainty of product development and commercialization, lack of marketing and sales history, dependence on key personnel, uncertainty of market acceptance of products and product reimbursement, product liability, uncertain protection of proprietary technology, potential inability to raise additional financing and compliance with the U.S. Food and Drug Administration and other government regulations.

The Company may require significant additional funds earlier than it currently expects in order to conduct additional clinical trials and continue to fund its operations. There can be no assurances, however, that additional funding will be available on favorable terms, or at all. If adequate funds are not available, the Company may be required to delay, significantly modify or terminate its research and development programs or reduce its planned commercialization efforts.

(2) Summary of Significant Accounting Policies

The accompanying condensed consolidated financial statements are unaudited, have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary to present fairly the Company’s financial position as of June 30, 2015 and the consolidated results of operations, comprehensive loss and cash flows for the three months and six months ended June 30, 2015 and 2014. The preparation of financial statements in conformity with accounting principles generally accepted in the United States (GAAP) requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from these estimates. The results of operations for the three months and six months ended June 30, 2015 are not necessarily indicative of the results to be expected for the year ending December 31, 2015 or for any other interim period or any other future year. For more complete financial information, these condensed financial statements, and the notes hereto, should be read in conjunction with the audited financial statements for the year ended December 31, 2014 included in the Company’s Annual Report on Form 10-K.

Principles of Consolidation

The condensed consolidated financial statements include the financial statements of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect certain reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. Significant items subject to such estimates and assumptions include contract research accruals, recoverability of long-lived assets, measurement of stock-based compensation, and the periods of performance under collaborative research and development agreements. The Company bases its estimates on historical experience and various other assumptions that management believes to be reasonable under the circumstances. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates.

Cash and Cash Equivalents

The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase and an investment in a money market fund to be cash equivalents. Changes in the level of cash and cash equivalents may be affected by changes in investment portfolio maturities, as well as actual cash disbursements to fund operations.

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The primary objective of the Company’s investment activities is to preserve its capital for the purpose of funding operations and the Company does not enter into investments for trading or speculative purposes. The Company’s cash is deposited in a highly rated financial institution in the United States. The Company invests in money market funds and high-grade, short-term commercial paper and corporate bonds, which management believes are subject to minimal credit and market risk. Declines in interest rates, however, would reduce future investment income.

Marketable Securities

Marketable securities consist of investments in high-grade corporate obligations, and government and government agency obligations that are classified as available-for-sale. Since these securities are available to fund current operations they are classified as current assets on the consolidated balance sheets.

The Company adjusts the cost of available-for-sale debt securities for amortization of premiums and accretion of discounts to maturity. The Company includes such amortization and accretion as a component of interest expense, net. Realized gains and losses and declines in value, if any, that the Company judges to be other-than-temporary on available-for-sale securities are reported as a component of interest expense, net. To determine whether an other-than-temporary impairment exists, the Company considers whether it intends to sell the debt security and, if the Company does not intend to sell the debt security, it considers available evidence to assess whether it is more likely than not that it will be required to sell the security before the recovery of its amortized cost basis. During the three months and six months ended June 30, 2015 and 2014, the Company determined it did not have any securities that were other-than-temporarily impaired.

Marketable securities are stated at fair value, including accrued interest, with their unrealized gains and losses included as a component of accumulated other comprehensive income or loss, which is a separate component of stockholders’ equity. The fair value of these securities is based on quoted prices and observable inputs on a recurring basis. Realized gains and losses are determined on the specific identification method. During the three months and six months ended June 30, 2015 and 2014, the Company did not have any realized gains or losses on marketable securities.

Fair Value of Financial Instruments

The carrying amounts of the Company’s financial instruments, which include cash equivalents, marketable securities and term loan obligations, approximate their fair values. The fair value of the Company’s financial instruments reflects the amounts that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy has the following three levels:

Level 1—quoted prices in active markets for identical assets and liabilities.

Level 2—observable inputs other than Level 1 inputs. Examples of Level 2 inputs include quoted prices in active markets for similar assets or liabilities and quoted prices for identical assets or liabilities in markets that are not active.

Level 3—unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability.

Financial assets and liabilities are classified in their entirety within the fair value hierarchy based on the lowest level of input that is significant to the fair value measurement. The Company measures the fair value of its marketable securities by taking into consideration valuations obtained from third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker-dealer quotes on the same or similar securities, issuer credit spreads, benchmark securities and other observable inputs. As of June 30, 2015, the Company’s financial assets valued based on Level 1 inputs consisted of cash and cash equivalents in a money market fund and its financial assets valued based on Level 2 inputs consisted of high-grade corporate bonds and commercial paper. During the three months and six months ended June 30, 2015 and 2014, the Company did not have any transfers of financials assets between Levels 1 and 2. As of June 30, 2015, the Company did not have any financial liabilities that were recorded at fair value on the balance sheet. The disclosed fair value of the Company’s term loan obligations is determined using current applicable rates for similar instruments as of the balance sheet date. The carrying value of the Company’s term loan obligations approximates fair value as the Company’s interest rate yield is near current market rate yields. The disclosed fair value of the Company’s term loan obligations is based on Level 3 inputs.

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Revenue Recognition

Collaboration and License Agreements

The Company’s principal source of revenue to date has been its former collaboration and license agreements, which included upfront license payments, development milestones, reimbursement of research and development costs, potential profit sharing payments, commercial and sales-based milestones and royalties. The accounting for collaboration and license agreements requires subjective analysis and requires management to make estimates and assumptions about whether deliverables within multiple-element arrangements are separable from the other aspects of the contractual arrangement into separate units of accounting and to determine the arrangement consideration to be allocated to each unit of accounting.

For multiple-element arrangements entered into or materially modified after January 1, 2011, the Company follows the provisions of Financial Accounting Standards Board (FASB) Accounting Standards Update (ASU) No. 2009-13— Multiple-deliverable Revenue Arrangements (ASU No. 2009-13). ASU No. 2009-13 amended certain provisions of Accounting Standards Codification (ASC) Topic 605— Revenue Recognition. This standard addresses the determination of the unit(s) of accounting for multiple-element arrangements and how an arrangement’s consideration should be allocated to each unit of accounting.

Pursuant to this standard, each required deliverable is evaluated to determine if it qualifies as a separate unit of accounting. For the Company this determination includes an assessment as to whether the deliverable has “stand-alone value” to the customer separate from the undelivered elements. The arrangement’s consideration is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. The estimated selling price of each deliverable is determined using the following hierarchy of values: (i) vendor-specific objective evidence of fair value, (ii) third-party evidence of selling price, or (iii) the Company’s best estimate of the selling price (BESP). The BESP reflects the Company’s best estimate of what the selling price would be if the deliverable was regularly sold by it on a stand-alone basis. The Company expects, in general, to use BESP for allocating consideration to each deliverable in future collaboration agreements. In general, the consideration allocated to each unit of accounting is then recognized as the related goods or services are delivered limited to the consideration not contingent upon future deliverables. The Company did not recognize any revenue related to collaboration and license agreements during the three months and six months ended June 30, 2015 and 2014.

The Company accounts for development milestones under collaboration and license agreements pursuant to ASU No. 2010-17 Milestone Method of Revenue Recognition (ASU No. 2010-17). ASU No. 2010-17 codified a method of revenue recognition that has been common practice. Under this method, contingent consideration from research and development activities that is earned upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved. At the inception of each arrangement that includes milestone payments, the Company evaluates whether each milestone is substantive. This evaluation includes an assessment of whether (a) the consideration is commensurate with either (1) the entity’s performance to achieve the milestone, or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity’s performance to achieve the milestone, (b) the consideration relates solely to past performance and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment. The Company does not have any ongoing collaboration and license agreements under which milestones may be achieved.

Royalty revenues are based upon a percentage of net sales. Royalties from the sales of products will be recorded on the accrual basis when results are reliably measurable, collectability is reasonably assured and all other revenue recognition criteria are met. Commercial and sales-based milestones, which are based upon the achievement of certain agreed-upon sales thresholds, will be recognized in the period in which the respective sales threshold is achieved and collectability is reasonably assured. The Company does not have any ongoing collaboration and license agreements under which royalties or commercial and sales-based milestones may be achieved.

Stock-Based Compensation

The Company recognizes stock-based compensation expense based on the grant date fair value of stock options granted to employees, officers and directors. The Company uses the Black-Scholes option pricing model to determine the grant date fair value as management believes it is the most appropriate valuation method for its option grants. The Black-Scholes model requires inputs for risk-free interest rate, dividend yield, volatility and expected lives of the options. Expected volatility is based upon the weighted average historical volatility data of the Company’s common stock. The risk-free rate for periods within the expected life of the option is based on the U.S. Treasury yield curve in effect at the time of the grant. The expected lives for options granted represent the period of time that options granted are expected to be outstanding. The Company uses the simplified method for determining the expected lives of options. The Company estimates the forfeiture rate based on historical data. This analysis is re-evaluated at least annually and the forfeiture rate

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is adjusted as necessary.

For awards with graded vesting, the Company recognizes compensation costs based on the grant date fair value of awards on a straight-line basis over the requisite service period, which is generally the vesting period.

Certain of the employee stock options granted by the Company are structured to qualify as incentive stock options (ISOs). Under current tax regulations, the Company does not receive a tax deduction for the issuance, exercise or disposition of ISOs if the employee meets certain holding requirements. If the employee does not meet the holding requirements, a disqualifying disposition occurs, at which time the Company may receive a tax deduction. The Company does not record tax benefits related to ISOs unless and until a disqualifying disposition is reported. In the event of a disqualifying disposition, the entire tax benefit is recorded as a reduction of income tax expense. The Company has not recognized any income tax benefit for its share-based compensation arrangements due to the fact that the Company does not believe it is more likely than not it will realize the related deferred tax assets.

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Changes in unrealized gains and losses on marketable securities represent the only difference between the Company’s net loss and comprehensive loss.

Segment Reporting

Operating segments are determined based on the way management organizes its business for making operating decisions and assessing performance. The Company has a single operating segment, which is the discovery, development and commercialization of drug products.

Basic and Diluted Loss Per Common Share

Basic net loss per share is computed using the weighted average number of common shares outstanding during the period, excluding restricted stock that has been issued but is not yet vested. Diluted net loss per common share is computed using the weighted average number of common shares outstanding and the weighted average dilutive potential common shares outstanding using the treasury stock method. However, for the three months and six months ended June 30, 2015 and 2014, diluted net loss per share is the same as basic net loss per share as the inclusion of weighted average shares of unvested restricted common stock and common stock issuable upon the exercise of stock options would be anti-dilutive.

The following table summarizes outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive:

Recent Accounting Pronouncements

In May 2014, the FASB issued ASU No. 2014-09, —Revenue from Contracts with Customers (Topic 606), which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in ASC Topic 605, and creates a new Topic 606, Revenue from Contracts with Customers. This guidance is effective for fiscal years beginning after December 15, 2016, with early adoption not permitted. Two adoption methods are permitted: retrospectively to all prior reporting periods presented, with certain practical expedients permitted; or retrospectively with the cumulative effect of initially adopting the ASU recognized at the date of initial application. In April 2015, the FASB proposed a one year deferral of the effective date of this standard to annual periods beginning after December 15, 2017, along with an option to permit companies to early adopt the standard for annual periods beginning after December 15, 2016. The Company has not yet determined which adoption method it will utilize or the effect that the adoption of this guidance will have on its consolidated financial statements.

In August 2014, the FASB issued ASU No. 2014-15, —Presentation of Financial Statements—Going Concern (Subtopic

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205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. This ASU is intended to define management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern within one year of the date of issuance of the entity’s financial statements and to provide related footnote disclosures. This guidance is effective for fiscal years ending after December 15, 2016, with early application permitted. The Company has not yet determined the effect that the adoption of this guidance will have on the disclosures included in its consolidated financial statements.

(3) Cash, Cash Equivalents and Marketable Securities

A summary of cash, cash equivalents and available-for-sale marketable securities held by the Company as of June 30, 2015 and December 31, 2014 was as follows in thousands (see Note 2):

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(4) Property and Equipment

Property and equipment as of June 30, 2015 and December 31, 2014 consisted of the following (in thousands):

Depreciation and amortization expenses of property and equipment, including equipment purchased under capital leases, were approximately $0.1 million in each of the three months ended June 30, 2015 and 2014, and $0.3 million in each of the six months ended June 30, 2015 and 2014, respectively.

(5) Stockholders’ Equity

Common Stock

Each common stockholder is entitled to one vote for each share of common stock held. The common stock will vote together with all other classes and series of stock of the Company as a single class on all actions to be taken by the Company’s stockholders. Each share of common stock is entitled to receive dividends, as and when declared by the Company’s board of directors.

The Company has never declared cash dividends on its common stock and does not expect to do so in the foreseeable future.

Public Offering

In April 2015, the Company raised approximately $44.3 million in gross proceeds from the sale of an aggregate 25,300,000 shares of its common stock in a public offering at a public offering price of $1.75 per share, including 3,300,000 shares upon the full exercise of the underwriters’ option to purchase additional shares. Certain of the Company’s directors and their affiliates, including its largest stockholder, purchased an aggregate of 7,257,142 shares in this offering at the public offering price. The net offering proceeds to the Company were approximately $41.8 million after deducting underwriters’ discounts, fees and commissions, and other offering expenses payable by the Company.

At-The-Market Issuance Sales Agreement

In July 2014, the Company entered into an at-the-market issuance sales agreement (July 2014 Sales Agreement) with MLV & Co. LLC (MLV), pursuant to which the Company may issue and sell shares of its common stock from time to time, at the Company’s option, through MLV as its sales agent. Sales of common stock through MLV may be made by any method that is deemed an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including by means of ordinary brokers’ transactions at market prices, in block transactions or as otherwise agreed by the Company and MLV. Subject to the terms and conditions of the Sales Agreement, MLV will use commercially reasonable efforts to sell the common stock based upon the Company’s instructions (including any price, time or size limits or other customary parameters or conditions the Company may impose). The Company is not obligated to make any sales of its common stock under the Sales Agreement. Any shares sold will be sold pursuant to an effective shelf registration statement on Form S-3. The Company will pay MLV a commission of up to 3% of the gross proceeds. The Company may terminate the July 2014 Sales Agreement at any time.

In July 2014, the Company reserved up to $50 million under its shelf registration statement for issuance under the July 2014 Sales Agreement. In the third quarter of 2014, the Company sold an aggregate of 5,679,685 shares of common stock pursuant to the July 2014 Sales Agreement for an aggregate of approximately $23.0 million in gross proceeds at an average selling price of $4.05 per share. Net proceeds to the Company were approximately $22.5 million after deducting commissions and other transaction costs. As of June 30, 2015, approximately $27.0 million remained reserved under the Company’s shelf registration statement and the applicable prospectus supplement for possible future issuance under the July 2014 Sales Agreement.

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(6) Stock-Based Compensation

The Company’s 2006 Stock Plan provided for the grant of incentive stock options, non-statutory stock options and non-vested restricted stock to employees, officers, directors and consultants of the Company. In January 2015, the number of shares of common stock reserved for issuance under the 2006 Stock Plan was increased from 10,300,000 to 11,600,000 pursuant to an “evergreen” provision, which provides for an annual increase based on the lesser of 1,300,000 shares, 5% of the Company’s then outstanding shares of common stock, or such other amount as the board of directors may determine. This increase was approved by the board of directors in December 2014. In June 2015, upon obtaining stockholder approval at its annual shareholder meeting, the Company implemented its new 2015 Stock Plan and reserved 8,741,000 shares of common stock for future issuance. In June 2015, the Company terminated its 2006 Stock Plan. The administration of these stock plans is under the general supervision of the compensation committee of the board of directors. The exercise price of the stock options is determined by the compensation committee of the board of directors, provided that incentive stock options are granted with an exercise price not less than fair market value of the common stock on the date of grant and expire no later than ten years from the date the option is granted. Options generally vest over four years. As of June 30, 2015, the Company had options outstanding to purchase 9,565,682 shares of its common stock, which includes options outstanding under its 2001 Stock Plan and 2006 Stock Plan that were terminated in March 2006 and June 2015, respectively. As of June 30, 2015, 8,740,968 shares were available for future issuance.

The following table summarizes stock option activity during the six months ended June 30, 2015:

The total cash received by the Company as a result of stock option exercises during the six months ended June 30, 2015 and 2014 was $0 and $0.8 million, respectively. The weighted-average grant date fair values of options granted during the three months ended June 30, 2015 and 2014 were $1.87 and $3.39, respectively, and during the six months ended June 30, 2015 and 2014 were $1.91 and $5.01, respectively.

Non-Vested (“Restricted”) Stock Awards with Service Conditions

The Company’s share-based compensation plans provide for awards of restricted shares of common stock to employees, officers, directors and consultants to the Company. Restricted stock awards are subject to forfeiture if employment or service terminates during the prescribed retention period. Restricted shares vest over the service period. The total fair value of restricted stock that vested in each of the six months ended June 30, 2015 and 2014 was $0.1 million.

The following table summarizes unvested restricted share activity during the six months ended June 30, 2015:

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Stock-Based Compensation Expense

For the three months and six months ended June 30, 2015 and 2014, the fair value of each employee stock option award was estimated on the date of grant based on the fair value method using the Black-Scholes option pricing valuation model with the following weighted average assumptions:

Stock-based compensation expense during the three months and six months ended June 30, 2015 and 2014 was as follows (in thousands):

Unrecognized stock-based compensation expense as of June 30, 2015 was as follows (dollars in thousands):

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7) Other Accrued Liabilities

Other accrued liabilities as of June 30, 2015 and December 31, 2014 consisted of the following (in thousands):

(8) Co-Development and License Agreements

Co-Development Agreement

In July 2011, the Company entered into a co-development agreement with a clinical research organization (CRO) for the conduct of certain company-sponsored clinical trials. Under the co-development agreement, this CRO was performing clinical research services under a reduced fee structure in exchange for a share of licensing payments and commercial revenues, if any, resulting from the product under development up to a specified maximum payment, which is defined as a multiple of the fee reduction realized. Research and development expenses were being recognized based on the reduced fee structure and expected payments will be recorded in the future if and when payment is probable. The maximum amount of the service fee discount was realized in the year ended December 31, 2013.

License Arrangement

In May 2014, the Company entered into a license arrangement for its CRACM program, including two lead candidates and the associated intellectual property portfolio, with PRCL Research Inc. (PRCL), a company funded by TVM Life Science Venture VII and the Fonds de Solidarité des Travailleurs du Québec, based in Montreal, Canada. PRCL plans to develop one of the two lead candidates licensed from the Company to proof-of-concept. Synta was granted a minority interest in PRCL in exchange for its contribution of know-how and intellectual property and will also hold a seat on PRCL’s Board of Directors. Synta will not be required to provide any research funding or capital contributions to PRCL. Synta will be reimbursed by PRCL for any ongoing intellectual property management costs in connection with the contributed intellectual property and may conduct preclinical research activities which would be reimbursed by PRCL. If and when proof-of-concept is reached with either drug candidate, Eli Lilly and Company, which is an investor in TVM, will manage the development program through one of its divisions and will have an option to acquire PRCL or its assets at the then fair value.

(9) Term Loans

General Electric Capital Corporation

In March 2013, the Company amended its loan and security agreement entered into in September 2010 with General Electric Capital Corporation (GECC) and another lender (the GECC Term Loan) and obtained $12.9 million in additional loan funding and, as a result, increased the principal balance to $22.5 million at March 31, 2013. This amendment was accounted for as a loan modification. Interest on the borrowings under the GECC Term Loan remains at the annual rate of 9.75%. In January 2014, the Company began making 30 equal monthly payments of principal plus accrued interest on the outstanding balance. During the period from July 2012 through March 2013, the Company made nine equal monthly payments of principal under the GECC Term Loan. For the periods from April 2013 through December 2013 and prior to July 2012 the Company made interest-only payments.

The Company has paid various transaction fees and expenses in connection with the GECC Term Loan, which are deferred and are being amortized as interest expense over the remaining term of the GECC Term Loan. In addition, the Company is obligated to pay an exit fee of $788,000 at the time of the final principal payment which is being accreted and expensed as interest over the remaining term of the GECC Term Loan. In the three months ended June 30, 2015 and 2014, the Company recognized GECC Term Loan interest expense of $0.3 million and $0.6 million, respectively, of which $0.1 million was in connection with these transaction and exit fees and expenses in each of the quarters. In the six months ended June 30, 2015 and 2014, the Company recognized GECC Term Loan interest expense of $0.7 million and $1.2 million, respectively, of which $0.1 million and $0.2 million, respectively, was in connection with these transaction and exit fees and expenses. The Company may prepay the full amount of the GECC Term Loan, subject to prepayment premiums under certain circumstances. The Company did not issue any warrants in connection with the GECC Term Loan.

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The GECC Term Loan is secured by substantially all of the Company’s assets, except its intellectual property. The Company has granted GECC a springing security interest in its intellectual property in the event the Company is not in compliance with certain cash usage covenants, as defined therein. The GECC Term Loan contains restrictive covenants, including the requirement for the Company to receive the prior written consent of GECC to enter into loans, other than up to $4.0 million of equipment financing, restrictions on the declaration or payment of dividends, restrictions on acquisitions, and customary default provisions that include material adverse events, as defined therein. The Company has determined that the risk of subjective acceleration under the material adverse events clause is remote and therefore has classified the outstanding principal based on the timing of scheduled principal payments.

Oxford Finance Corporation

In March 2011, the Company entered into a loan and security agreement with Oxford Finance Corporation (Oxford) and received $2.0 million in loan funding, and in December 2012, the Company entered into a loan modification agreement, as amended, under which the Company could elect to draw down up to an additional $0.6 million in equipment financing until June 30, 2013 that would be payable in 36 equal monthly payments of principal plus accrued interest on the outstanding balance (collectively, the Oxford Term Loan). As of June 30, 2013, the Company had fully utilized the $0.6 million in additional equipment financing. Interest on the borrowings under the Oxford Term Loan accrues at an annual rate of 13.35%. In May 2011, the Company began making 36 equal monthly payments of principal plus accrued interest on the initial $2.0 million outstanding balance that was fully paid in April 2014. The Company continues to make equal monthly payments of principal plus accrued interest on the $0.6 million in additional equipment financing. The Company recognized approximately $11,000 and $14,000 in interest expense in the three months ended June 30, 2015 and 2014, respectively, and $24,000 and $35,000 in interest expense in the six months ended June 30, 2015 and 2014, respectively, related to the outstanding principal under the Oxford Term Loan. In addition to the interest payable under the Oxford Term Loan, the Company paid approximately $108,000 of administrative and legal fees and expenses in connection with the Oxford Term Loan. These expenses have been deferred and are being expensed over the term of the Oxford Term Loan. The Company did not issue any warrants in connection with the Oxford Term Loan. The Company may prepay the Oxford Term Loan, subject to prepayment premiums under certain circumstances. Oxford has the right to require the Company to prepay the Oxford Term Loan if the Company prepays the full amount of the GECC Term Loan under certain circumstances.

The Oxford Term Loan is secured by certain laboratory and office equipment, furniture and fixtures. In connection with the Oxford Term Loan, Oxford and GECC entered into a Lien Subordination Agreement, whereby GECC granted Oxford a first priority perfected security interest in the loan collateral. The Oxford Term Loan contains restrictive covenants, including the requirement for the Company to receive the prior written consent of Oxford to enter into acquisitions in which the Company incurs more than $2.0 million of related indebtedness, and customary default provisions that include material adverse events, as defined therein. The Company has determined that the risk of subjective acceleration under the material adverse events clause is remote and therefore has classified the outstanding principal in current and long-term liabilities based on the timing of scheduled principal payments.

Future principal payments under the GECC and Oxford Term Loans as of June 30, 2015 were approximately as follows (in thousands):

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

You should read this discussion together with the condensed consolidated financial statements, related notes and other financial information included elsewhere in this Quarterly Report on Form 10-Q. The following discussion may contain predictions, estimates and other forward-looking statements that involve a number of risks and uncertainties, including those discussed under “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2014 filed with the Securities and Exchange Commission on March 12, 2015. These risks could cause our actual results to differ materially from any future performance suggested below.

Overview

Synta Pharmaceuticals Corp. is an innovative, agile biopharmaceutical company focused on research, development and commercialization of novel oncology medicines that have the potential to change the lives of cancer patients. Our lead oncology drug candidate, ganetespib, a novel heat shock protein 90 (Hsp90) inhibitor, is currently being evaluated in several large randomized clinical trials including GALAXY-2, a pivotal Phase 3 trial in non-small cell lung cancer (NSCLC), as well as breast cancer, ovarian cancer and acute myeloid leukemia (AML). We are also evaluating several candidates from our proprietary Hsp90 inhibitor Drug Conjugate program (HDC Program), which leverages the preferential accumulation of Hsp90 inhibitors in tumors to selectively deliver a wide array of anti-cancer payloads. Our first clinical candidate from our HDC Program, STA-12-8666, is undergoing testing to enable the filing of an investigational new drug application (IND). Preclinical evaluation of additional HDC candidates is ongoing. We also have an additional clinical-stage oncology candidate: elesclomol, a mitochondrial metabolism inhibitor.

We were incorporated in March 2000 and commenced operations in July 2001. Since that time, we have been principally engaged in the discovery and development of novel drug candidates. As of June 30, 2015, we have raised an aggregate of approximately $861.0 million in cash proceeds to fund operations, including $658.0 million in net proceeds from private and public offerings of our equity, $30.5 million in gross proceeds from term loans and $167.2 million in non-refundable payments from partnering activities under prior collaborations, as well as $5.3 million from the exercise of common stock warrants and options. We have also generated funds from government grants, equipment lease financings and investment income. We are engaged in preliminary partnership discussions for a number of our programs, which may provide us with additional financial resources if consummated.

We have devoted substantially all of our capital resources to the research and development of our drug candidates. Since our inception, we have had no revenues from product sales. As of June 30, 2015, we had an accumulated deficit of $678.1 million. We expect to incur significant operating losses for the foreseeable future as we advance our drug candidates from discovery through preclinical development and clinical trials, and seek regulatory approval and eventual commercialization. We will need to generate significant revenues from product sales to achieve future profitability and may never do so.

On April 22, 2015, Anne Whitaker notified our Board of Directors that she was resigning as our President and Chief Executive Officer and as a member of our Board of Directors, effective as of May 7, 2015. On April 23, 2015, in connection with Ms. Whitaker’s resignation and effective as of May 7, 2015, the Board of Directors (i) appointed Chen Schor, our then-current Executive Vice President and Chief Operating Officer, as President and Chief Executive Officer and (ii) appointed Mr. Schor as a Class I director with a term expiring at the annual meeting of stockholders to be held in 2017 to fill the vacancy to be created by Anne Whitaker’s resignation.

In April 2015, we sold 25,300,000 shares of our common stock in a public offering for approximately $41.8 million in net proceeds. See “—Liquidity and Capital Resources—Public Offering.”

Program Overview

We have two clinical-stage programs in oncology (ganetespib and elesclomol) and a novel, proprietary small molecule cancer drug development program (the HDC platform).

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Ganetespib (Hsp90 Inhibitor)

Summary

Ganetespib is a novel, potent, small molecule inhibitor of Hsp90, a molecular chaperone which is required for the proper folding and activation of many cancer-promoting proteins. Inhibition of Hsp90 by ganetespib leads to the simultaneous degradation of many of these client proteins and the subsequent death or cell cycle arrest of cancer cells dependent on those proteins. A number of Hsp90 client proteins are also involved in the resistance of cancer cells to other anti-cancer treatments, such as chemotherapy. The ability to reduce cancer-cell drug resistance suggests that the combination of ganetespib with chemotherapies or other anti-cancer agents may provide greater benefit than those agents administered alone. In preclinical studies, ganetespib has shown potent anti-cancer activity against a broad range of solid and hematologic cancers, both as a monotherapy and in combination with a variety of anti-cancer treatment approaches including chemotherapy, radiation, targeted therapy and immunotherapy.

The results observed to date in our GALAXY program suggest a significant potential commercial opportunity for use of ganetespib in patients with advanced non-small cell lung adenocarcinoma. Lung cancer is the leading cause of cancer death worldwide in both men and women, estimated to be responsible for about 1.6 million deaths or approximately 20% of global cancer deaths in 2012. NSCLC is the most common form of lung cancer, making up approximately 85% to 90% of all lung cancers. Adenocarcinoma is the most common subtype of NSCLC.

Ganetespib Mechanism of Action

Hsp90 is required for the structural and functional maturation of numerous client proteins, many of which play critical roles in cell growth, differentiation and survival. Preclinical results have shown that ganetespib is a selective inhibitor of Hsp90. Relative to their normal counterparts, cancer cells are more reliant on the active Hsp90 complex. Recent published work has shown that cancer cells overexpress a modified form of Hsp90 that preferentially binds Hsp90 inhibitors. This preferential binding provides a possible explanation for the observed anticancer activity and lack of severe toxicity of Hsp90 inhibitors.

Ganetespib in lung cancer: The GALAXY program

GALAXY-1 Phase 2b Trial

In 2011, we initiated the GALAXY-1 trial in patients with advanced NSCLC who received one prior treatment for advanced disease, i.e., a second-line treatment setting. GALAXY-1 compared treatment with docetaxel alone, which is approved for second-line treatment, to treatment with ganetespib plus docetaxel. The aims of this trial were to:

·            evaluate clinical benefit and establish the safety profile of ganetespib in combination with docetaxel relative to docetaxel alone;

·            identify the patient populations, by biomarker or other disease characteristics, which may be most responsive to combination treatment; and

·            build the clinical and operational experience needed to optimize the design and execution of the pivotal GALAXY-2 Phase 3 trial.

Patients in both arms of GALAXY-1 received a standard regimen of docetaxel 75 mg/m2 on day 1 of a 21-day treatment cycle. Patients in the combination arm also received ganetespib 150 mg/m 2  on days 1 and 15. Treatment continued until disease progression or until treatment intolerance. To ensure balance of prognostic factors between the two arms, patients were stratified by ECOG performance status, baseline LDH level, smoking status, and time since diagnosis of advanced disease.

Rate of disease progression during or following first line chemotherapy is a common stratification factor in salvage-setting (after first-line treatment) lung cancer clinical trials to ensure balance and evaluate any difference in treatment benefit between refractory and chemosensitive patients. Commonly used measures include time since completion of first line chemotherapy, best response to first line therapy, time since initiation of first line therapy, as well as time since diagnosis of advanced disease. The latter was chosen for GALAXY-1 in order to reduce ambiguity introduced by the use of maintenance therapy following first line treatment, as well as to avoid possible subjectivity in assessment of tumor response in the first-line setting.

GALAXY-1 was originally designed to enroll 240 second-line advanced NSCLC patients of all histologies in order to evaluate several hypotheses on which patients might be most responsive to combination treatment. Co-primary endpoints were progression-free survival (PFS) in all patients (the ITT population) and overall survival (OS) in patients with elevated baseline levels of serum LDH (eLDH). During the course of the trial, the co-primary endpoints were changed to PFS in patients with eLDH and PFS in patients with

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mutant KRAS (mKRAS). Key secondary endpoints were OS and PFS in the adenocarcinoma patient population.

In early 2012, enrollment of patients with non-adenocarcinoma histologies (which consists primarily of squamous cell carcinomas) was terminated based on possible safety concerns, including risk of bleeding and a trend towards inferior survival. The trial was amended at that time to enroll 240 patients with adenocarcinoma histology only. To ensure the specified number of eLDH and mKRAS patients were included, a total of 385 patients were enrolled in GALAXY-1. Enrollment in GALAXY-1 was completed in May 2013 with the final analysis conducted in early May 2014. The final GALAXY-1 results were published in the May 21, 2015 online first issue of Annals of Oncology. A summary of key efficacy data is presented in the tables and figures below:

*The Dx > 6 months population selected for the Phase 3 GALAXY-2 trial are patients who were enrolled into the GALAXY-1 study at least 6 months after diagnosis of advanced disease (a stratification factor in the Phase 2b GALAXY-1 trial).

P-values are 1-sided

Hazard ratios were calculated using Cox proportional hazards model

Unadjusted: univariate analysis

Adjusted: pre-specified analysis adjusting for multiple prognostic variables such as gender, smoking status, LDH, ECOG performance status, interval since diagnosis of advanced disease, age, total baseline target lesion size, and geographic region

*The Dx > 6 months population selected for the Phase 3 GALAXY-2 trial are patients who were enrolled into the GALAXY 1 study at least 6 months after diagnosis of advanced disease (a stratification factor in the Phase 2b GALAXY-1 trial).

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Figure 3: OS Kaplan Meier plot for the Dx > 6 months patient population of GALAXY-1 selected for evaluation in the GALAXY-2 Phase 3 trial

Figure 4: PFS Kaplan Meier plot for the Dx > 6 months patient population of GALAXY-1 selected for evaluation in the GALAXY-2 Phase 3 trial

Safety

The safety profile of adenocarcinoma patients treated with the combination of ganetespib (G) and docetaxel (D) was favorable, consistent with previously reported results. The most common adverse events (AEs), all grades, were neutropenia (46% vs. 45%), diarrhea (50% vs. 17%) and fatigue (35% vs. 24%), for G+D vs. D, respectively. Diarrhea was effectively prevented or managed with standard supportive care; the incidence of grade 3 or 4 diarrhea was 4% (G+D) vs. 0% (D). Fatigue was predominantly grade 1 and grade 2; grade 3 or 4 fatigue was 6% (G+D) vs. 4% (D). The most common grade 3 or 4 AEs were neutropenia (41% vs. 42%), leukopenia (10% vs 6%) and febrile neutropenia (9% vs. 5%). Only one case of visual impairment was reported in this study, which was mild (Grade 1) and transient. The safety profile of patients in the Dx > 6 months population was comparable to the profile in the adenocarcinoma population.

GALAXY-2 Phase 3 Trial

In early 2013, we initiated the GALAXY-2 trial, a global, randomized, multi-center study comparing the same treatments as in GALAXY-1 in the 2nd-line non-small cell adenocarcinoma patient population, with overall survival as the primary endpoint. Patients are required to have an interval since diagnosis of advanced disease of at least 6 months prior to study entry and have tumors that are negative for both EGFR mutations and ALK translocations.

Patients on both arms receive docetaxel generally for four to six 21-day cycles, according to standard practice at their treatment center. After completion of docetaxel treatment, patients on the ganetespib arm are eligible to continue to receive ganetespib monotherapy as maintenance treatment.

The GALAXY-2 trial protocol provides for enrollment of up to 850 patients. Assuming a median overall survival of 7 months in the control arm and 9.3 months in the combination arm (a hazard ratio of 0.75) and a two-sided overall Type I error rate of 0.05, GALAXY-2 has a 92% or higher power to detect a statistically significant treatment difference at the final analysis. The primary

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endpoint analysis will be based on an evaluation of OS in the intent-to-treat population, and a pre-specified analysis of OS in ALK- and EGFR-negative patients will be conducted as a supportive analysis. Two event-driven interim analyses of the overall survival primary endpoint of GALAXY-2 have been pre-specified. The first and second interim analyses will be performed after approximately 60% and 80% of the OS events required for final analysis have occurred, respectively.

Based on current projections and statistical assumptions, we expect that the first GALAXY-2 interim OS analysis will be conducted by the end of 2015 and that the second interim OS analysis and the final OS analysis will be conducted in 2016. Assuming positive interim results from the ongoing GALAXY-2 trial of ganetespib and pending regulatory feedback, we plan to seek regulatory approval of ganetespib for NSCLC in 2016.

Ganetespib in breast cancer

I-SPY 2 Trial

In 2014, ganetespib was selected for study in the I-SPY 2 TRIAL (Investigation of Serial Studies to Predict Your T herapeutic  R esponse with  I maging  A nd mo L ecular Analysis 2). I-SPY 2 is a standing Phase 2 randomized, controlled, multicenter trial for women with newly diagnosed, locally advanced breast cancer (Stage 2 or higher) that is designed to test whether adding investigational drugs to standard chemotherapy is better than standard chemotherapy alone in the neo-adjuvant setting (prior to surgery).

I-SPY 2 employs a unique adaptive trial design to match experimental therapies with patients. Genetic or biological markers (“biomarkers”) from individual patients’ tumors are used to screen promising new treatments, identifying which treatments are most effective in specific patient subgroups. Regimens that have a high Bayesian predictive probability of showing superiority in a 300 patient Phase 3 confirmatory trial in at least one of 10 predefined signatures may “graduate” from I-SPY 2. A regimen can graduate early and at any time after having a minimum of 35 patients assigned to it, and exits the trial after a maximum of 75 patients. This high efficacy bar and rapid turnaround time allows the trial to match the most promising drug with the right patient in the most expeditious fashion.

I-SPY 2 was created as a pre-competitive consortium that brings together the Food and Drug Administration (FDA), National Cancer Institute (NCI), pharmaceutical companies, leading academic medical centers, and patient advocacy groups under its umbrella. I-SPY 2 is sponsored by QuantumLeap Healthcare Collaborative (QLHC), a non-profit 501(c)(3) foundation dedicated to accelerating healthcare solutions. QLHC shares a unique partnership with the Foundation for the National Institutes of Health Biomarkers Consortium, who manages intellectual property that emerges from the trial. The trial was developed by principal investigators, Laura J. Esserman, M.D., M.B.A., Professor of Surgery and Radiology and Director of the Carol Frank Buck Breast Care Center at UCSF Helen Diller Family Comprehensive Cancer Center in San Francisco, and Donald A. Berry, Ph.D., Professor in the Department of Biostatistics at The University of Texas MD Anderson Cancer Center, and founder of Berry Consultants.

Enrollment in the ganetespib arm of I-SPY 2 began in October 2014. Ganetespib is initially available to patients with HER2 negative disease, with the possibility to expand its eligibility to all biomarker subtypes after safety testing with trastuzumab is completed.

Clinical trial of ganetespib and fulvestrant in patients with hormone receptor positive metastatic breast cancer

This randomized Phase 2 trial is evaluating safety and activity of the fulvestrant and ganetespib combination in patients with hormone receptor positive metastatic breast cancer who are experiencing progression after initial treatment with hormonal therapy. At present, patient recruitment is ongoing. The trial is sponsored by Dana Farber Cancer Institute in Boston.

Clinical trial of ganetespib in combination with paclitaxel and trastuzumab in HER2 positive metastatic breast cancer

Preliminary results from this Phase 1 trial, conducted by physicians at New York University Langone Medical Center and Memorial Sloan Kettering Cancer Center, were presented at the 2014 San Antonio Breast Cancer Symposium in December. The trial was designed to evaluate the safety and preliminary activity of the triplet combination of ganetespib, paclitaxel and trastuzumab in HER2 positive patients with metastatic breast cancer refractory to other HER2 inhibitors.

As of December 2014, this Phase 1 trial enrolled six heavily pretreated patients who received prior to entering the trial a median of 3.5 anti-HER2 treatments in the metastatic setting (range 3-4), including trastuzumab, pertuzumab, and ado-trastuzumab emtansine (T-DM1).

Of the five patients evaluable for efficacy, partial tumor response was observed in one patient who remains on study, and four patients achieved stable disease ranging in duration from 11 to 29 weeks. Median Progression Free Survival was 19.4 weeks and the observed Clinical Benefit Rate (proportion of patients achieving objective response or stable disease greater than 24 weeks) was 60%.

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Ganetespib in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS)

AML is a rapidly progressing hematologic cancer characterized by uncontrolled proliferation of immature blast cells in the bone marrow. The American Cancer Society estimates that there were approximately 18,860 new cases of AML in 2014 and approximately 10,460 people died from AML in 2014. MDS is a hematopoietic stem cell neoplasm characterized by disordered and ineffective hematopoiesis which results in irreversible decline in the number and quality of blood-forming cells. In most cases, progressive bone marrow failure results in neutropenia and thrombocytopenia, and in about one third of patients the disease progresses into AML, usually within a few years.

AML is a biologically heterogeneous disease, and therefore represents a major challenge in the advancement of treatment. Treatment choice and outcome are substantially decided by age, yet current long term remission rates remain poor, with only 40% of younger patients (age less than 60 years) and less than 10% of older patients (age equal to or greater than 60 years) achieving complete remissions. AML patients with relapsed or refractory disease and newly diagnosed AML patients over 60 years of age with poor prognostic risk factors typically die within one year, resulting in an acute need for new treatment options for these patients.

Starting in 2011, the Leukemia & Lymphoma Research Fund and Cancer Research UK sought to fund and initiate three large, multicenter, randomized trials to evaluate different investigational treatments, alone or in combination with chemotherapy, in patients with first-line AML and high risk MDS. These trials are being conducted under the sponsorship of Cardiff University, UK, and under the auspices of the UK NCRI Haematological Oncology Study Group, with investigators in Denmark, France, New Zealand, and the United Kingdom. Ganetespib, in combination with chemotherapy, has been selected for investigation in all three of these studies, which have initiated, or are expected to initiate by the end of 2015:

·            The AML-LI (Less Intensive)-1 Phase 2/3 trial is ongoing, and is evaluating the combination of ganetespib with low dose cytarabine (Ara-C) vs. low dose Ara-C alone in patients who are not eligible for intensive chemotherapy and are traditionally not included in most trials. In July 2014, we announced advancement of ganetespib into the Phase 3 extension of this trial, following an interim analysis of results from 50 patients who received the ganetespib-cytarabine combination in the Phase 2 portion of the trial. The primary efficacy outcome in Phase 2 was rate of complete response. Pursuant to the protocol, the Phase 3 extension will include an interim futility analysis and enroll approximately 200 patients in each of the ganetespib-cytarabine and the cytarabine alone arms, for a total of approximately 400 patients. The primary efficacy endpoint for the Phase 3 extension is overall survival.

·            The AML-18 trial, which has initiated and began enrolling patients in the first quarter of 2015, will evaluate ganetespib with standard DA (daunorubicin and Ara-C) in patients over 60 years old who can tolerate intensive chemotherapy vs. treatment with standard DA alone. Up to 300 patients are expected to be enrolled in the ganetespib arm. Results from a pilot study conducted in the UK in 2012 under the auspices of the Cardiff Experimental Cancer Medicine Centre confirmed the feasibility and safety of combining ganetespib with intensive chemotherapy in older patients with AML.

·            The AML-19 trial, which is expected to begin enrolling patients by the end of 2015, will evaluate ganetespib in combination with conventional chemotherapy vs chemotherapy alone in younger patients with AML. The trial is expected to enroll more than 500 patients in the ganetespib arm and will be conducted by the UK NCRI Group, a network of over 100 institutions. Patients will receive ganetespib sequentially to standard intensive therapy, followed by ganetespib maintenance treatment. The objective is to identify if ganetespib reduces the risk of relapse in the overall population or in key subgroups, and as a result, improves overall survival, the primary endpoint.

The selection of ganetespib for these studies was supported by preclinical results generated by us and academic collaborators, including Alan K. Burnett formerly of Cardiff University, and Sanjay Bansal of the UT Health Science Center at San Antonio. Results from these studies show that ganetespib inhibits a number of cancer-promoting factors believed to contribute to the proliferation of leukemic cells and renders them more vulnerable to treatment with chemotherapy.

Ganetespib in ovarian cancer

GANNET53 Trial

According to the World Health Organization, approximately 239,000 new cases of ovarian cancer are diagnosed worldwide each year. Ovarian cancer is among the most deadly of the gynecologic cancers, causing approximately 152,000 deaths annually, including approximately 42,700 deaths in Europe and 15,400 deaths in the United States.

GANNET53, a Seventh Framework Programme (FP7) research project funded by the European Commission, is a pan-European randomized trial designed to evaluate the combination of ganetespib and paclitaxel vs. paclitaxel alone in over 200 patients with metastatic, predominantly p53 mutant, platinum-resistant ovarian cancer. Preclinical models have shown that mutant p53 is critical to the growth and proliferation of these cancers. Many mutations render p53 unable to fold appropriately, leaving the protein highly dependent on Hsp90 for stability. Inhibition of Hsp90 destroys the complex between Hsp90 and mutant p53, leading to the degradation of the protein and cancer cell death. We believe this hypothesized mechanism is further supported by results detailed in a July 2015 Nature publication, Improving survival by exploiting tumor dependence on stabilized mutant p53 for treatment, by E.M. Alexandrova, et

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al. Mice harboring mutant p53 treated with ganetespib had prolonged survival as compared to treated p53 null mice, and this activity is correlated with degradation of mutant p53 and tumor apoptosis.  In aggregate, we believe these data suggest the potential of mutated p53 to serve as a predictive biomarker for Hsp90 inhibitors such as ganetespib.

Hsp90 inhibition has also been shown to sensitize mutant p53 cancer cells to treatment with chemotherapies, as has been seen in preclinical studies evaluating ganetespib in other tumor types, supporting the planned trial design evaluating the combination of ganetespib and paclitaxel vs. paclitaxel alone.

Enrollment of the safety lead-in Phase 1 portion of GANNET53 in centers in Austria, Belgium, France, and Germany began in July 2014 and is now complete.  Initial results from the Phase 1 portion presented in June 2015 at the American Society of Clinical Oncology (ASCO) Annual Meeting demonstrated the feasibility and tolerability of combining ganetespib and paclitaxel in this treatment setting.  In June 2015, we announced that the first patient was enrolled into the randomized Phase 2 portion of the trial.

A Phase I/II trial of paclitaxel in combination with ganetespib in patients with platinum-resistant ovarian cancer

This trial is designed to evaluate the safety and preliminary activity of the combination of ganetespib with weekly paclitaxel in patients with recurrent, platinum-resistant ovarian, fallopian tube or primary peritoneal cancer. The trial is sponsored by Fox Chase Cancer Center in Philadelphia, and initiated in the first half of 2014.

Ganetespib in Sarcoma

In November 2014, we announced an invitation from the FDA to participate in a meeting of the Oncologic Drugs Advisory Committee’s (ODAC) Pediatric Subcommittee on December 11, 2014. The purpose of the meeting was to inform the FDA as to whether there is sufficient interest in the pediatric sarcoma investigator community to warrant the FDA issuing a Pediatric Written Request to Synta. If the FDA issues a Pediatric Written Request and we fulfill its requirements, an additional six months of exclusivity in the US will be granted to ganetespib.

SARC 023, sponsored by the Sarcoma Alliance for Research through Collaboration (SARC), is an open label Phase 1/2 trial of ganetespib in combination with the mTOR inhibitor sirolimus in patients with refractory sarcoma, including malignant peripheral nerve sheath tumors (MPNSTs). The Pediatric Subcommittee of ODAC reviewed the design of SARC 023, as well as pre-clinical data demonstrating the scientific rationale for studying this combination in a clinical trial. The Phase 1 portion of the study, which is currently ongoing, is designed to assess the safety, tolerability, and maximum tolerated/recommended dose of the combination.

Ganetespib in additional oncology indications

In addition to the trials noted above, a number of ganetespib trials sponsored by third parties, including cooperative groups, foundations, and individual investigators have recently been completed or are ongoing.  Among these studies are:

·    a Phase I trial evaluating the combination of ganetespib with capecitabine and radiation in patients with locally advanced rectal cancer being sponsored by Emory University, which began enrolling patients in 2012.  Results from this trial presented at the 2015 ASCO Annual Meeting demonstrated the feasibility of combining ganetespib and chemoradiation therapy in these patients;

·    a Phase I/II trial evaluating ganetespib in combination with pemetrexed and cisplatin in patients with malignant pleural mesothelioma, being sponsored by University College London and Cancer Research UK, which began enrolling patients in 2013; and

·    a Phase I trial evaluating ganetespib in combination with carboplatin, paclitaxel and radiation in patients with stage I or II esophageal carcinoma, being sponsored by University of Texas MD Anderson, which began enrolling patients in June 2015.

HDC Program: STA-12-8666 (SN-38 HDC)

In September 2013, we announced the launch of a novel, proprietary small molecule cancer drug development program: the HDC Program. This innovative approach to tumor targeted delivery is being developed to capitalize on the prolonged retention of Hsp90 inhibitors in tumors to trap an active agent of interest inside cancer cells. The HDC Program builds on our extensive expertise in the science of Hsp90.

The HDC platform is based on the observation that small molecule inhibitors of Hsp90 are retained in tumors for as much as 20 times longer than in blood or normal tissue. Preclinical experiments have shown that following intravenous administration in animals, ganetespib can persist in tumor cells for over a week, while it is cleared from blood and normal tissues in a matter of hours. Similar results demonstrating this characteristic have been published by others using first-generation Hsp90 inhibitors such as 17-AAG and its derivatives, as well as other classes of Hsp90 inhibitors.

HDCs are drug candidates consisting of an Hsp90 inhibitor (targeting moiety) joined to an anti-cancer agent (payload) via a cleavable chemical linker optimized for controlled release of payload drug inside cancer cells. HDCs are small molecules that do not rely

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on cell surface antigens for targeting and internalization for cellular uptake. Upon cell entry, typically via small molecule uptake (passive diffusion and possibly active transporter), HDCs can bind intracellular Hsp90 that is present in significant amounts in a wide range of cancers.

Figure 5: The HDC Program: using the preferential retention of Hsp90 inhibitors by tumor cells to selectively deliver anti-cancer payloads.

Upon systemic administration HDCs have the potential to achieve significantly higher concentrations of active anticancer drugs (payloads) in tumors than the concentrations achieved when such anticancer drugs are given in their original, unconjugated form. It is important to note that such high concentrations are sustained over prolonged periods of time, thus significantly increasing the exposure of tumors to the anticancer drug relative to the exposure that can be achieved when such anticancer drugs are given in their original, unconjugated form.

In October 2013, we announced the publication of the first key patent application covering our proprietary HDC technology, which includes composition of matter claims covering HDC compounds, methods for identifying therapeutically effective compounds, and methods of use against a wide range of diseases and conditions. Any resulting patent, if issued, would expire no earlier than 2034.

Our lead drug candidate from our HDC Program is STA-12-8666, a conjugate of an Hsp90 inhibitor bound to SN-38, the highly potent active metabolite of the widely used chemotherapy irinotecan. Several factors led to the choice of SN-38 as an HDC payload:

·            SN-38 has a well-established pharmacological profile;

·            in humans, the metabolic conversion of irinotecan to active SN-38 is a highly complex and relatively inefficient process, subject to a high degree of inter-individual variability and low conversion rates that combine to restrict active drug bioavailability;

·            SN-38 is one of the most potent payloads which has been widely used in novel drug delivery technology development; and

·            SN-38 is relatively small with a flat chemical structure, which may facilitate passive diffusion

These issues of variability, bioavailability and solubility have previously stimulated considerable interest in utilizing irinotecan and/or SN-38 in other delivery formulations intended to improve drug pharmacokinetics and therapeutic activity. With STA-12-8666, our team has sought to leverage the preferential accumulation of Hsp90 inhibitors in tumors to selectively deliver SN-38 and address these issues.

Preclinical results generated to date for STA-12-8666 illustrate the differentiated profile of STA-12-8666 as compared to irinotecan. Highlights of these results include:

·            Favorable biodistribution.  STA-12-8666 demonstrates prolonged SN-38 activity following a single dose. In addition, STA-12-8666 and its components, including SN-38, have been shown to preferentially persist in tumors as compared to irinotecan. Detectable amounts of SN-38 in tumors are observed 5 days following STA-12-8666 administration, whereas levels of SN-38 declined rapidly below quantifiable limits by 72 hours with irinotecan administration in MDA-MB231 tumor bearing mice.

·            Efficacy in a broad range of tumors.  STA-12-8666 has been tested in more than a dozen tumor models where it has been shown to be superior to irinotecan at the equivalent doses and at their respective maximum tolerated doses (MTDs). In addition, STA-12-8666 has also been shown to be superior to the combination of irinotecan and a potent Hsp90 inhibitor in a model of small cell lung cancer (SCLC) at MTD.

·            Durable efficacy in aggressive tumor models.  STA-12-8666 has been shown to induce durable complete responses in in vivo models of melanoma, NSCLC, and other solid tumors.

·            Improved tolerability.  In animal toxicology studies conducted to date, STA-12-8666 has also shown an improved tolerability profile as compared to irinotecan.

Importantly, STA-12-8666 has also demonstrated sustained efficacy in chemo-resistant preclinical models of difficult to treat solid

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tumors. Of note, STA-12-8666 has demonstrated significant activity in patient derived xenograft (PDX) models of pancreatic cancer and SCLC. In results obtained in collaboration with investigators at Fox Chase Cancer Center, STA-12-8666 demonstrated durable antitumor activity in a resistant pancreatic patient derived xenograft (PDX) preclinical model.

Figure 6: Durable antitumor activity of STA-12-8666 in chemo-resistant pancreatic Patient Derived Xenografts (PDX).

Interestingly, tumors which progressed >1 month following last treatment rapidly respond to a second course of treatment, suggesting limited resistance to STA-12-8666; tumors which progressed received no additional STA-12-8666 treatment.

Taken together, we believe that the results obtained to date with STA-12-8666 have demonstrated its potential to be a viable clinical candidate and provide initial proof of concept in our HDC Program. In the first quarter of 2015, we advanced STA-12-8666 into IND enabling studies targeting an IND submission by the first quarter of 2016. We expect to identify one additional HDC drug candidate to nominate for preclinical development in the first half of 2016 and hope to initiate IND-enabling studies in 2016.

Elesclomol (Mitochondria-Targeting Agent)

Elesclomol is a first-in-class investigational drug candidate that triggers programmed cell death (apoptosis) in cancer cells through a novel mechanism: disrupting cancer cell energy metabolism. Preclinical experiments and findings in three randomized clinical trials have shown that lactate dehydrogenase (LDH), a key enzyme in cellular energy metabolism, is an important predictor of elesclomol treatment outcome.

We are evaluating the use of elesclomol in combination with paclitaxel in ovarian cancer. In March 2011, the Gynecological Oncology Group (GOG) initiated a Phase 2 clinical trial of elesclomol in combination with paclitaxel for the treatment of persistent or recurrent ovarian, fallopian tube or primary peritoneal cancer for patients with total baseline serum LDH level less than 0.8 times the upper limit of normal (ULN). The GOG is a non-profit organization with the purpose of promoting excellence in the quality and integrity of clinical and basic scientific research in the field of gynecologic malignancies. The National Cancer Institute is providing financial support of up to approximately $300,000 for the trial through its Cancer Therapy Evaluation Program. The ovarian cancer trial met the pre-specified efficacy requirement to advance to stage 2, indicating potential activity in this difficult-to-treat patient population with limited treatment options. Enrollment of stage 2 of this study has been completed.

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Financial Operations Overview

Revenue

We have not yet generated any product revenue and may never do so. Our revenues to date have been generated primarily through our former collaboration and license agreements. The terms of these agreements included payment to us of upfront license fees, milestone payments, research and development cost sharing and royalties. We will seek to generate revenue from product sales and from future collaborative or strategic relationships. In the future, we expect any revenue we generate will fluctuate from quarter-to-quarter as a result of the timing and amount of payments received and expenses incurred under future collaborations or strategic relationships, if consummated, and the amount and timing of payments we receive upon the sale of our drug candidates, to the extent any are successfully commercialized.

Research and Development

Research and development expense consists of costs incurred in connection with developing and advancing our drug discovery technology and identifying and developing our drug candidates. We charge all research and development expenses to operations as incurred.

Our research and development expense consists of:

·   internal costs associated with research, preclinical and clinical activities;

·   payments to third party contract research organizations, investigative sites and consultants in connection with our preclinical and clinical development programs;

·   costs associated with drug formulation and supply of drugs for clinical trials;

·   personnel related expenses, including salaries, bonuses, stock-based compensation, benefits and travel; and

·   overhead expenses, including rent and maintenance of our facilities, and laboratory and other supplies.

We do not know if we will be successful in developing any of our drug candidates. We believe that accurately projecting total program-specific expenses through commercialization is not possible at this time. The timing and amount of these expenses will depend upon the costs associated with current and potential future clinical trials of our drug candidates, and any expansion of our research and development organization, regulatory requirements, advancement of our preclinical programs and product manufacturing costs, many of which cannot be determined with accuracy at this time based on the stage of development of our drug candidates. This is due to the numerous risks and uncertainties associated with the duration and cost of clinical trials, which vary significantly over the life of a project as a result of unanticipated events arising during clinical development, including with respect to:

·            the number of clinical sites included in the trial;

·            the length of time required to enroll suitable subjects;

·            the number of subjects that ultimately participate in the trials; and

·            the efficacy and safety results of our clinical trials and the number of additional required clinical trials.

Our expenditures are subject to additional uncertainties, including the terms and timing of regulatory approvals. In addition, we may obtain unexpected or unfavorable results from our clinical trials. We may elect to discontinue, delay or modify clinical trials of some drug candidates or focus on others. A change in the outcome of any of the foregoing variables in the development of a drug candidate could mean a significant change in the costs and timing associated with the development of that drug candidate. For example, if the FDA or other regulatory authority were to require us to conduct clinical trials beyond those that we currently anticipate, or if we experience significant delays in any of our clinical trials, we would be required to expend significant additional financial resources and time on the completion of clinical development. Additionally, future commercial and regulatory factors beyond our control will evolve and therefore impact our clinical development programs and plans over time.

We anticipate that overall research and development costs may increase as we continue to advance our ganetespib program through the GALAXY-2 trial, our Phase 3 trial in second-line advanced NSCLC, towards commercialization, conduct a full year of the I-SPY 2 breast cancer trial, and advance STA-12-8666, the lead drug candidate from our HDC Platform, into clinical development.

Beyond our current lead drug candidates, we anticipate that we will select drug candidates and research projects for further development on an ongoing basis in response to their preclinical and clinical success, as well as commercial potential.

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General and Administrative

General and administrative expense consists primarily of salaries, bonuses and related expenses for personnel in executive, finance, business and commercial development, investor and medical community relations, human resources and administrative functions. Other costs include stock-based compensation costs, directors’ and officers’ liability insurance premiums, legal costs of pursuing patent protection of our intellectual property, fees for general legal, accounting, public-company requirements and compliance, and other professional services, as well as overhead-related costs not otherwise included in research and development. We anticipate that general and administrative expense may increase in 2015 depending upon the rate at which we expand our pre-commercialization activities related to ganetespib.

Critical Accounting Policies and Estimates

Our management’s discussion and analysis of our financial condition and results of operations are based on our financial statements which have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reported periods. We are required to make estimates and judgments with respect to contract research accruals, the recoverability of long-lived assets, measurement of stock-based compensation and the periods of performance under collaboration and license agreements. We base our estimates on historical experience, known trends and events, and various other factors that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources and the reported amounts of revenues and expenses. Actual results may differ from these estimates under different assumptions or conditions.

You should read the following discussion of our reported financial results in conjunction with the critical accounting policies disclosed in our Annual Report on Form 10-K for the year ended December 31, 2014, as filed with the Securities and Exchange Commission on March 12, 2015. There have been no significant changes to our critical accounting policies in 2015 to-date.

Consolidated Results of Operations

Three Months Ended June 30, 2015 Compared with Three Months Ended June 30, 2014

Revenues

There were no revenues in each of 2015 and 2014.

Research and Development Expense

Ganetespib

In 2015 as compared to 2014, costs incurred under our ganetespib program decreased by $2.7 million, including decreases of $1.0 million in personnel-related costs, related research supplies, operational overhead and stock compensation resulting from a lower level of FTEs, and $1.7 million in external costs. Decreases in external costs principally resulted from lower costs incurred in 2015 in connection with the wind-down of the GALAXY-1 trial, the ENCHANT-1 trial and other company-sponsored trials, partially offset by the conduct of a full quarter of the I-SPY-2 breast cancer trial that commenced enrollment in October 2014. External costs incurred in the second quarter of 2015 in connection with the GALAXY-2 trial, our Phase 3 trial in second-line advanced NSCLC, were comparable to the level of costs incurred in the same period in 2014. We anticipate that costs under the ganetespib program may increase as we continue to advance the program through the GALAXY-2 trial towards commercialization and conduct a full year of the I-SPY 2 breast cancer trial.

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STA-12-8666

In 2015 as compared to 2014, costs incurred under our STA-12-8666 program increased by $2.1 million, including increases of $1.0 million in personnel-related costs, related research supplies, operational overhead and stock compensation, and $1.1 million in external costs. In the first quarter of 2015, we commenced pre-clinical development of our lead HDC candidate, STA-12-8666, and expect to submit an IND by the first quarter of 2016. We anticipate that costs under the STA-12-8666 program will increase in 2015 as we advance the pre-clinical development of STA-12-8666.

Elesclomol

In 2015 as compared to 2014, costs incurred under our elesclomol program decreased by $0.1 million, principally due to a decrease of $0.1 million in external costs related to the pace of the ongoing clinical trial in ovarian cancer. We anticipate that future costs under our elesclomol program will remain at nominal levels as the ongoing clinical trial in ovarian cancer being conducted by the GOG nears completion.

Early-stage programs

In 2015 as compared to 2014, costs incurred under our early stage programs decreased by $1.7 million, including decreases in personnel-related costs, related research supplies, operational overhead and stock compensation. In 2015, we advanced our lead HDC candidate, STA-12-8666, into pre-clinical development and expect to nominate one additional HDC candidate for IND enabling studies in the first half of 2016. We anticipate that our HDC discovery costs will decrease in 2015 as a result of the more focused research effort.

General and Administrative Expense

In 2015 as compared to 2014, general and administrative expenses increased by $0.2 million principally related to net increases of $0.2 million in external professional fees. We anticipate that general and administrative expense may increase in 2015 depending upon the rate at which we expand our pre-commercialization activities related to ganetespib.

Interest Expense, net

In 2015 as compared to 2014, interest expense decreased due to principal payments under the GECC Term Loan and the original three-year $2.0 million loan under the Oxford Term Loan. We anticipate that interest expense will decrease in 2015 as we continue to make principal payments under the GECC Term Loan.

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Six Months Ended June 30, 2015 Compared with Six Months Ended June 30, 2014

Revenues

There were no revenues in each of 2015 and 2014.

Research and Development Expense