SIXTH AMENDMENT TO LEASE AGREEMENT

Exhibit 10.1

This SIXTH AMENDMENT TO LEASE AGREEMENT (this “Sixth Amendment”) is entered into as of this 11 ^th day of October, 2007 by and between OYSTER POINT TECH CENTER, LLC, a Delaware limited liability company (“ Landlord ”), and VAXGEN, INC., a Delaware corporation (“ Tenant ”).

A.         Landlord is the owner of the Project known as Oyster Point Tech Center (the “Project”), which consists of two 2-story buildings for a total of approximately 105,120 square feet, with details as follows: (i) the building commonly known as 347 Oyster Point Boulevard, South San Francisco, California containing approximately 39,780 square feet (the “ 347 Oyster Point Building ”), and (ii) the building commonly known as 349 Oyster Point Boulevard, South San Francisco, California containing approximately 65,340 square feet (the “ 349 Oyster Point Building ”).

B.         Landlord and Tenant are parties to that certain Lease entered into on or about October 26, 1998 (the “ Initial Lease ”), as amended by that certain First Amendment dated as of June 1, 1999 (the “ First Amendment ”), that certain Second Amendment dated as of June 1, 1999 (the “ Second Amendment ”), that certain Third Amendment dated as of October 5, 2000 (the “ Third Amendment ”), that certain Fourth Amendment dated as of March 31, 2004 (the “ Fourth Amendment ”) and that certain Fifth Amendment dated as of April 14, 2005 (the “ Fifth Amendment ”). Collectively, the Initial Lease, the First Amendment, the Second Amendment, the Third Amendment, the Fourth Amendment and the Fifth Amendment are referred to herein as the “ Original Lease ”.

C.         Pursuant to the Original Lease, Landlord leases to Tenant and Tenant leases from Landlord the entire 347 Oyster Point Building and the entire 349 Oyster Point Building.

D.         Tenant desires to surrender to Landlord all of Tenant’s right, title and interest in and to the entire 347 Oyster Point Building (the “ Surrendered Premises ”), and to terminate the Original Lease as it relates only to the Surrendered Premises, and Landlord desires to accept said surrender and termination, all on the terms and conditions of this Sixth Amendment. The Surrendered Premises is designated on the plan attached hereto and incorporated herein as Exhibit A .

E.         Landlord and Tenant further desire to amend the Original Lease to, among other things, adjust the Base Rent for the remainder of the term of the Original Lease for the 349 Oyster Point Building, all in accordance with the terms and conditions set forth below.

F.         Unless otherwise defined herein, all capitalized terms used herein shall have the meanings ascribed to them in the Original Lease. The Original Lease, as amended hereby, shall herein and hereafter be referred to as the “Lease.” All references in the Lease to the “Lease” shall herein and hereafter refer to the Original Lease, as

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amended hereby.

AGREEMENT

NOW, THEREFORE, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant hereby agree as follows:

1.           Premises . Subject to the terms of this Sixth Amendment, effective as of March 1, 2008 (the “ Effective Date ”), the “Premises” shall no longer include the Surrendered Premises and instead shall include only the 65,340 square feet of space in the 349 Oyster Point Building (the “ New Premises ”), as such New Premises is more particularly described shown on Exhibit B attached hereto. Effective as of the Effective Date (but subject to the terms of this Sixth Amendment), all references in the Lease to “Premises” shall mean and refer to the New Premises.

2.           Surrender of Surrendered Premises . On the Effective Date, Tenant shall surrender to Landlord the Surrendered Premises in clean condition, free of Tenant’s general office furniture and personal property, in good repair and free of Hazardous Substances. Notwithstanding the foregoing, Tenant may leave within the Surrendered Premises furniture and personal property that Tenant has transferred ownership to Monogram Bioscience, provided that a detailed inventory of such furniture and personal property, signed by both Tenant and Monogram Bioscience, is delivered to Landlord prior to the Effective Date. Notwithstanding any provision in the Original Lease to the contrary, except as to Trade Fixtures, Tenant shall not remove any Alterations or Tenant Improvements in the Surrendered Premises or to make any modifications to the Surrendered Premises except as necessary to surrender the Surrendered Premises in the condition required by the first sentence of this Paragraph. Notwithstanding the foregoing, Tenant shall not remove any component of a parent system that as a result of removal would cause that system to function improperly such as HVAC, water distribution, gas distribution (examples of these components would include but not be limited to fume hoods and water purification equipment). From and after the Effective Date, the Lease (as it relates only to the Surrendered Premises) shall terminate and neither Landlord nor Tenant (nor any subtenants, licensees or assignees of Tenant) shall have any rights, duties or obligations to one another in connection with the Lease as it relates only to the Surrendered Premises) except for those obligations under the Lease to the extent not pertaining to the Surrendered Premises, and the following (the following are collectively referred to herein as the “ Surviving Obligations ”): (a) in the event that Tenant does not properly surrender the Surrendered Premises in accordance with the terms of the Lease, the performance by Tenant of its obligations under the Lease with respect to the Surrendered Premises (including, without limitation, the payment of holdover rent) until such time as Tenant has properly surrendered the Surrendered Premises (provided, however, the foregoing is in no way intended to provide Tenant with any right to delay its obligation to properly surrender the Surrendered Premises on or before the Effective Date); and (b) those obligations under this Sixth Amendment and/or under the Original Lease which expressly survive the expiration or earlier termination of the Lease,

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including, without limitation, Tenant’s indemnification obligations contained in the Lease with respect to conditions existing or events occurring prior to the Effective Date. Notwithstanding the above, Tenant’s indemnification obligations under the Lease shall not apply to any damage, claims or liabilities arising solely out of the entry into the Surrendered Premises by Landlord, any prospective or actual tenant for the Surrendered Premises or any other third party entering the Surrendered Premises for purposes of designing, modifying or otherwise preparing the Surrendered Premises for re-letting. The Cummins 1500 Kw emergency generator located in the east side of the parking lot is not connected to the Surrendered Premises and remains appurtenant to the New Premises.

3.           Release . Except for such obligations, rights or claims as may be created by or arise out of the terms and conditions of this Sixth Amendment, effective on the Effective Date, Tenant, on behalf of itself and its predecessors, successors, affiliates and assigns, and all other persons, firms and corporations claiming through Tenant, and each of them (collectively, the “ Tenant Releasing Parties ”), does hereby release Landlord and its predecessors, successors, affiliates and assigns, and their respective partners, officers, shareholders, agents, contractors, representatives, employees and attorneys (collectively the “ Landlord Released Parties ”), of and from any and all claims, demands, disputes, damages, liabilities, obligations, controversies, debts, costs, expenses, lawsuits, actions, causes of action and other rights to relief, both legal and equitable, of every kind and nature, whether now known or unknown, suspected or unsuspected, past or present, contingent or fixed, which the Tenant Releasing Parties, or any of them, now have, had, or at any time hereafter may have, against the Landlord Released Parties, or any of them, arising out of or in connection with the Lease (as it relates only to the Surrendered Premises) or the Surrendered Premises. In consideration of the Surrender Fee and the covenants and releases set forth herein and except for Tenant’s obligations that survive the expiration or earlier termination of the Lease as set forth or preserved in this Sixth Amendment, effective on the Effective Date, Landlord hereby releases Tenant from any and all claims, demands, obligations and liabilities which Landlord may have or would have against Tenant had the Lease with respect to the Surrendered Premises not been terminated by this Sixth Amendment, including, without limitation, damages, Rent, Basic Operating Costs, Management Fee, late fees, interest, leasing commissions, and attorney’s fees and costs that would be incurred by Landlord on account of any of the claims, demands, obligations or liabilities released by Landlord herein. Notwithstanding the above, the parties shall be responsible for the annual reconciliation of Basic Operating Costs for the Surrendered Premises as set forth in the Lease and any attorney’s fees and costs incurred in the collection thereof.

4.           California Civil Code Section 1542 . Except with respect to the Surviving Obligations, Tenant and Landlord each hereby expressly waives all rights which either of them has, or may hereafter claim to have, that any claim, demand, obligation and/or cause of action has, through ignorance, oversight or error, been omitted from the terms of this Sixth Amendment with respect to the Surrendered Premises, and hereby expressly waives all rights it may have, or claim to have, under the provisions of California Civil Code Section 1542, or equivalent law of any jurisdiction, which provides:

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“A GENERAL RELEASE DOES NOT EXTEND TO CLA