EXHIBIT 10.10.3

[*] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, IS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO RULE 24B-2 OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

GLOBEIMMUNE, INC.

STOCK PURCHASE AGREEMENT

THIS STOCK PURCHASE AGREEMENT (the “Agreement”) is made as of the 8^th day of August, 2003, by and between GLOBEIMMUNE, INC., a Delaware corporation (the “Company”), and University License Equity Holding, Inc. (“Purchaser”).

WHEREAS, the Company desires to issue, and Purchaser desires to acquire, stock of the Company as herein described, on the terms and conditions hereinafter set forth;

NOW, THEREFORE, IT IS AGREED between the parties as follows:

1. Purchase and Sale of Stock. Purchaser hereby agrees to purchase from the Company, and the Company hereby agrees to sell to Purchaser, an aggregate of [*] ([*]) shares (the “Shares”) of the Common Stock of the Company (the “Stock”), pursuant to the transfer of intellectual property rights pursuant to (a) the Intellectual Property License Agreement, dated September 18, 1997, between the Company and University Technology Corporation and, (b) the Intellectual Property License Agreement, dated September 24, 1998, between the Company and University Technology Corporation (the agreements listed in clauses (a) and (b), the “License Agreements”). The closing hereunder, including payment for and delivery of the Shares shall occur at the offices of the Company immediately following the execution of this Agreement, or at such other time and place as the parties may mutually agree.

2. Limitations on Transfer. Purchaser shall not assign, hypothecate, donate, encumber or otherwise dispose of any interest in the Stock except in compliance with the provisions herein and applicable securities laws. Furthermore, the Stock shall be subject to any right of first refusal in favor of the Company or its assignees that may be contained in the Company’s Bylaws. The Company shall not be required (a) to transfer on its books any shares of Stock of the Company which shall have been transferred in violation of any of the provisions set forth in this Agreement or (b) to treat as owner of such shares or to accord the right to vote as such owner or to pay dividends to any transferee to whom such shares shall have been so transferred. Notwithstanding, the foregoing, Purchaser shall be permitted to transfer the Stock to the University of Colorado (“CU”) with the Company’s prior written consent (which shall not be unreasonably withheld); provided that, following such transfer (i) any of the Stock so transferred shall remain subject to the Company’s Bylaws, (ii) CU shall be bound by the provisions of this Agreement, and (iii) CU shall make no further transfers of all or part of the Stock except pursuant to this Agreement.

3. Agreement. Purchaser and Company agree and acknowledge that as of the date hereof, the Shares are represent the complete obligation of the Company to deliver equity to Purchaser pursuant to the License Agreements. Purchaser hereby generally, irrevocably, unconditionally and completely releases and forever discharges the Corporation, its officers and directors, each of the Investors, and each of the other Original Stockholders from, and hereby irrevocably, unconditionally and completely waives and relinquishes, any rights it may have arising on or before the time immediately prior to the execution of this Stock Purchase Agreement.

[*] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, IS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO RULE 24B-2 OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

4. Restrictive Legends. All certificates representing the Stock shall have endorsed thereon legends in substantially the following forms (in addition to any other legend which may be required by other agreements between the parties hereto):

(a) “THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 AS AMENDED. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AS TO THE SECURITIES UNDER SAID ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.”

(b) “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A RIGHT OF FIRST REFUSAL OPTION IN FAVOR OF THE COMPANY AND/OR ITS ASSIGNEE(S) AS PROVIDED IN THE BYLAWS OF THE COMPANY.”

(c) Any legend required by appropriate blue sky officials.

5. Investment Representations. In connection with the purchase of the Stock, Purchaser represents to the Company the following:

(a) Purchaser is aware of the Company’s business affairs and financial condition and has acquired sufficient information about the Company to reach an informed and knowledgeable decision to acquire the Stock. Purchaser is purchasing the Stock for investment for Purchaser’s own account only and not with a view to, or for resale in connection with, any “distribution” thereof within the meaning of the Act.

(b) Purchaser understands that the Stock has not been registered under the Act by reason of a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of Purchaser’s investment intent as expressed herein.

(c) Purchaser further acknowledges and understands that the Stock must be held indefinitely unless the Stock is subsequently registered under the Act or an exemption from such registration is available. Purchaser further acknowledges and understands that the Company is under no obligation to register the Stock. Purchaser understands that the certificate evidencing the Stock will be imprinted with a legend which prohibits the transfer of the Stock unless the Stock is registered or such registration is not required in the opinion of counsel for the Company.

(d) Purchaser is familiar with the provisions of Rules 144, under the Act, as in effect from time to time, which, in substance, permit limited public resale of “restricted securities” acquired, directly or indirectly, from the issuer thereof (or from an affiliate of such issuer), in a non-public offering subject to the satisfaction of certain conditions.

The Stock may be resold by Purchaser in certain limited circumstances subject to the provisions of Rule 144, which requires, among other things: (i) the availability of certain public information about the Company and (ii) the resale occurring following the required holding period under Rule 144 after the Purchaser has purchased, and made full payment of (within the meaning of Rule 144), the securities to be sold.

[*] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, IS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO RULE 24B-2 OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

(e) Purchaser further understands that at the time Purchaser wishes to sell the Stock there may be no public market upon which to make such a sale, and that, even if such a public market then exists, the Company may not be satisfying the current public information requirements of Rule 144, and that, in such event, Purchaser would be precluded from selling the Stock under Rule 144 even if the minimum holding period requirement had been satisfied.

(f) Purchaser further warrants and represents that Purchaser has either (i) preexisting personal or business relationships, with the Company or any of its officers, directors or controlling persons, or (ii) the capacity to protect his own interests in connection with the purchase of the Stock by virtue of the business or financial expertise of himself or of professional advisors to Purchaser who are unaffiliated with and who are not compensated by the Company or any of its affiliates, directly or indirectly.

6. Market Stand-Off Agreement. Purchaser shall not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any Common Stock of the Company held by Purchaser, including the Stock (the “Restricted Securities”), for a period of time specified by the managing underwriter(s) (not to exceed one hundred eighty (180) days) following the effective date of a registration statement of the Company filed under the Act. Purchaser agrees to execute and deliver such other agreements as may be reasonably requested by the Company and/or the managing underwriter(s) which are consistent with the foregoing or which are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to Purchaser’s Restricted Securities until the end of such period. The underwriters of the Company’s stock are intended third party beneficiaries of this Section 6 and shall have the right, power and authority to enforce the provisions hereof as though they were a party hereto.

7. Miscellaneous.

(a) Notices. All notices required or permitted hereunder shall be in writing and shall be deemed effectively given: (a) upon personal delivery to the party to be notified, (b) when sent by confirmed telex or facsimile if sent during normal business hours of the recipient, and if not during normal business hours of the recipient, then on the next business day, (c) five (5) calendar days after having been sent by registered or certified mail, return receipt requested, postage prepaid, or (d) one (1) business day after deposit with a nationally recognized overnight courier, specifying next day delivery, with written verification of receipt. All communications shall be sent to the other party hereto at such party’s address hereinafter set forth on the signature page hereof, or at such other address as such party may designate by ten (10) days advance written notice to the other party hereto.

(b) Successors and Assigns. This Agreement shall inure to the benefit of the successors and assigns of the Company and, subject to the restrictions on transfer herein set forth, be binding upon Purchaser, Purchaser’s successors, and assigns.

(c) Attorneys’ Fees; Specific Performance. Each party shall pay all costs and expenses that it incurs with respect to the negotiation, execution and delivery of this Agreement.

[*] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, IS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO RULE 24B-2 OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

(d) Governing Law; Venue. This Agreement shall be governed by and construed in accordance with the laws of the State of Colorado. The parties agree that any action brought by either party to interpret or enforce any provision of this Agreement shall be brought in, and each party agrees to, and does hereby, submit to the jurisdiction and venue of, the appropriate state or federal court for the district encompassing the Company’s principal place of business.

(e) Further Execution. The parties agree to take all such further action(s) as may reasonably be necessary to carry out and consummate this Agreement as soon as practicable, and to take whatever steps may be necessary to obtain any governmental approval in connection with or otherwise qualify the issuance of the securities that are the subject of this Agreement.

(f) Independent Counsel. Purchaser acknowledges that this Agreement has been prepared on behalf of the Company by Cooley Godward LLP, counsel to the Company and that Cooley Godward LLP does not represent, and is not acting on behalf of, Purchaser. Purchaser has been provided with an opportunity to consult with Purchaser’s own counsel with respect to this Agreement.

(g) Entire Agreement; Amendment. This Agreement constitutes the entire agreement between the parties with respect to the subject matter hereof and supersedes and merges all prior agreements or understandings, whether written or oral. This Agreement may not be amended, modified or revoked, in whole or in part, except by an agreement in writing signed by each of the parties hereto.

(h) Severability. If one or more provisions of this Agreement are held to be unenforceable under applicable law, the parties agree to renegotiate such provision in good faith. In the event that the parties cannot reach a mutually agreeable and enforceable replacement for such provision, then (i) such provision shall be excluded from this Agreement, (ii) the balance of the Agreement shall be interpreted as if such provision were so excluded and (iii) the balance of the Agreement shall be enforceable in accordance with its terms.

(i) Counterparts. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original and all of which together shall constitute one instrument.

IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the day and year first above written.

[*] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, IS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO RULE 24B-2 OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.