Exhibit 10.1
 [****] Certain information in this document, marked by brackets, has been omitted and filed separately with the Securities and Exchange Commission. Confidential treatment has been requested with respect to the omitted portions.
 EXECUTION COPY
 CO-DEVELOPMENT AND COMMERCIALIZATION AGREEMENT
 Agreement th Effective Date Astellas Maxygen Party Parties
 BACKGROUND




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##### 



ARTICLE 1
DEFINITIONS
  Accounting Standards
 Affiliate
 Alliance
 Alliance Technology provided, however
 Asia
 Astellas Technology
 Astellas Know-How
 -2-




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##### 



Astellas Patents
 Backup Clinical Candidate
 BLA et.
seq.
 Budget Budgets
 Bulk Drug Substance
 Business Day
 Clinical Candidate
 Co-Development Indication
 Commercialization
 -3-




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##### 



provided, however, Commercialize Commercializing
 Committee Committees
 Compound Exhibit 1.16 Existing Compound
 Compound Criteria Exhibit 1.17 Exhibit 1.17
 Control Controlled Controlling
 Co-Promotion Co-Promote
 -4-




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##### 



Co-Promotion Country
 Current Good Manufacturing Practices cGMP
 CTLA-4 Variant CTLA-4 Molecule
 Data
 Development [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -5-




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provided, however, Develop Developing
 Development Plans
 Diligent Efforts [****] provided, however, [****] [Astellas] [****] [****] [****]. [****] [****] [****] [****]
 Dollars $
 EMEA
 Europe
 Exclusive Indication
 FDA
 Field
 Financial Exhibit Exhibit 1.33
 Finished Drug Product
 Fiscal Year Fiscal Year 2010 Fiscal Year 2011
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -6-




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IND
 IND Enabling Studies
 Indication Exhibit 1.38
 Initiation
 Joint Commercialization Territory
 Joint Development Territory
 Know-How
 Law
 Lead Clinical Candidate
 -7-




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##### 



Licensed Technology
 Major Market Country Exhibit 1.46
 Manufacturing Manufacture
 Marketing Approval
 Marketing Approval Application MAA
 Maxygen Technology
 Maxygen Know-How
 Maxygen Patents
 -8-




---



##### 



Exhibit 1.50.2
 Next Generation Clinical Candidate
 North America
 Patent
 Phase I Clinical Trial
 Phase II Clinical Trial
 Phase III Clinical Trial
 -9-




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##### 



Phase IV Clinical Trial
 Plan Plans
 Preclinical Development [****] in vitro in vivo not
 Process Development
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -10-




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Product
 Regulatory Authority
 Regulatory Filing
 Rest of World ROW
 Royalty Bearing Territory
 Shuffle Shuffled Shuffling
 Shuffling Technology
 Territory
 Third Party
 -11-




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##### 



Treatment Treat Treating
 Valid Claim
 United States
 Additional Definitions
 Definitions
    
    SectionAdverse Drug Reaction
    
    
    6.2.4Adverse Safety/Tox Results
    
    
    13.2.2Affected Area
    
    
    13.4.2
    (e)(i)Agreement Wind-Down Period
    
    
    13.6.2Approved Maxygen CMO
    
    
    6.1.1
    (a)Approved Astellas CMO
    
    
    6.1.5Astellas Indemnitees
    
    
    12.5.1
    (a)Astellas Independent Inventions
    
    
    10.2.2
    (a)Astellas Requirements
    
    6.1.1(a)(iii)Astellas-Selected New Compounds
    
    
    13.4.2
    (e)(v)Backup Manufacturer
    
    6.1.6(b)(iv)Bundled Products
    
    
    5.4CDI Cessation Notice
    
    
    13.4.2
    (a)Claims
    
    
    12.5.1
    (a)Clinical Candidate Criteria
    
    
    3.3.1Co-Chair
    
    
    2.5.2Co-Development Activities
    
    
    2.3
    (b)Co-Development Indication Plan
    
    
    4.1.2Maxygens Co-
    
    
    13.4.2
    (c)Joint Steering Committee or JSC
    
    
    2.3JSC Matter
    
    
    2.7.1Losses
    
    
    12.5.1
    (a)Manufacturing Costs
    
    Fin. Ex. 5.13Marketing Costs
    
    Fin. Ex. 5.14Marks
    
    
    10.7Maxygen Indemnitees
    
    
    12.5.1
    (b)Maxygen Independent Inventions
    
    
    10.2.2
    (a)Maxygen Mark
    
    
    5.2.7Maxygen Opt-Out Right
    
    
    4.1.4
    (b)Maxygen Reverted Compound Activities
    
    13.4.2(e)(vii)Maxygen-Selected New Compounds
    
    
    13.4.2
    (e)(v)Milestone
    
    Fin. Ex. 1.1.1Net Sales
    
    Fin. Ex. 5.15New Manufacturer
    
    6.1.6(a)(iii)New Libraries
    
    
    13.4.2
    (e)(v)No-Fault Cause
    
    
    6.1.6
    (a)(i)Notifying Party
    
    
    7.2Operating Expenses
    
    Fin. Ex. 5.16
 -12-




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##### 



Definitions
    
    SectionDevelopmentIndication CostsCombination Product
    
    Fin. Ex. 2.1.3(c)Competing Activities
    
    
    7.1.1Competing Infringing Activities
    
    
    10.6Confidential Information
    
    
    11.1Controlling Party
    
    
    10.3.3Cooperating Party
    
    
    11.5.2Co-Promotion Notice
    
    
    5.2Co-Promotion Option
    
    
    5.2Co-Promotion Percentage
    
    
    5.2.1Co-Promotion Plan
    
    
    5.2.2
    (a)Co-Promotion Product
    
    
    5.2Core Countries
    
    
    10.3.1
    (a)Costs
    
    Fin. Ex. 5.2Damages
    
    
    10.5Development Costs
    
    Fin. Ex. 5.3Distributable Profits
    
    Fin. Ex. 5.4Divest
    
    
    7.2.3Direct Country
    
    
    9.1.3
    (a)Enforcement Action
    
    
    10.6Excluded Compounds
    
    13.4.2(e)(iii)Exclusivity Period
    
    
    7.1.1Existing Manufacturer
    
    6.1.6(a)(iii)Existing Third Party LicensesFault
    
    
    12.5.1
    (a)FTE
    
    Fin. Ex. 5.8Indemnified Party
    
    
    12.6Indemnifying Party
    
    
    12.6Initial Preclinical Development Plan
    
    
    3.2Joint Inventions
    
    
    10.2.2
    (a)Joint Patent
    
    
    10.3.2Joint Program Team or JPT
    
    
    2.4Opt-Out Notice
    
    
    4.1.4
    (b)Opt-Out Event
    
    
    4.1.4
    (b)Other Party
    
    
    7.2Permitted Activities
    
    
    7.1.3Post-Execution Affiliate
    
    
    7.2Preclinical Development Costs
    
    Fin. Ex. 5.20Preclinical Development Program
    
    
    3.1Preclinical Development Plan
    
    
    3.2Prior CDA
    
    
    11.3Prosecution and Maintenance
    
    
    10.3.5Publishing Party
    
    
    11.4.1Recoveries
    
    
    10.6.2Representing Party
    
    
    12.1Requesting Party
    
    
    11.5.2Responsibility Transfer Plan
    
    
    6.1.6
    (b)(i)Reverted Compounds
    
    13.4.2(e)(iii)Reviewing Party
    
    
    11.4.1Selected Indication
    
    
    4.1.3
    (a)Selected Indication Notice
    
    
    4.1.3
    (a)Separate Program
    
    
    7.2Shuffling Improvement
    
    
    10.2.2
    (b)Subcommittee
    
    
    2.9Subject Transaction
    
    
    7.2Supplies Requirement Plan
    
    6.1.1(a)(iii)Target
    
    
    11.2Term
    
    
    13.1Third Party License
    
    
    10.4.2Third Party Payments
    
    Fin. Ex. 2.1.3(a)Third Party Reverted
Compound Activities
    
    13.4.2(e)(viii)Walled-Off Programs
    
    
    11.2
 -13-




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##### 



Interpretation however
 -14-




---



##### 



ARTICLE 2
SCOPE AND GOVERNANCE OF THE ALLIANCE
 Scope and Conduct of the Alliance; Diligence
 Maxygen Inquiry; Cessation of Commercialization and Development
 Joint Steering Committee Joint Steering Committee JSC
   -15-




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##### 



Co-Development Activities
           -16-




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##### 



[****] [****]
     Joint Program Team Joint Program Team JPT
 Exhibit
3.2
   
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -17-




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During Preclinical Development Program
 During Development
 -18-




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##### 



During Commercialization
 For Manufacturing
 -19-




---



##### 



Committee Membership
 General Exhibit 2.5 [****]
 Co-Chairs Co-Chair [****] ad hoc
 Committee Meetings [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -20-




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ad hoc [****] [****] [****]
 Decision Making
 Generally [****] JSC Matter [****]
 Deciding Vote; Limitations provided however provided,
however [****] [****] [****] [****] [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -21-




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##### 



[****] [****] [****] [****]
 Matters Outside Deciding Vote or Outside Authority of JSC
 Reporting to the Committees
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -22-




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##### 



Subcommittees. Subcommittee [****]
 Interactions Between Committees and Internal Teams
 Performance of Representatives
 Day-to-Day Decision Making Authority
 Oversight of Costs
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -23-




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[****] [****]
 Use of the Other Partys Resources; Compliance with Plans provided,
however
 Use of Contractors provided however
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -24-




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##### 



Role of Committees with Respect to Activities Other Than Co-Development
Activities
 ARTICLE 3
PRECLINICAL DEVELOPMENT
 Preclinical Development Program Preclinical Development Program
 -25-




---



##### 



in vitro
 Preclinical Development Plan Preclinical Development Plan Exhibit 3.2 Initial Preclinical Development Plan [****] [****] [****] [****]
 Designation of Clinical Candidates
 General Designation of Clinical Candidates Exhibit 3.3 Clinical Candidate Criteria
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -26-




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Intellectual Property Matters
 Limitations
 Review of Existing Compounds
 -27-




---



##### 



Preclinical Development Program Information and Reports provided, however in vitro in vivo provided, however
 Cost Sharing
 ARTICLE 4
DEVELOPMENT
 Development of Products for Co-Development Indications for the Joint Development
Territory
 Development
 -28-




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##### 



Co-Development Indication Plans
 Co-Development Indication Plan [****] [****]
  
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -29-




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Maxygen Involvement in Clinical Trials
 Astellas Selection Selected Indication Selected Indication Notice [****]
 Maxygen Election [****] [****] [****] [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -30-




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##### 



provided however
 Limitation on Opt-Out Right [****] [****] [****]
 Other Agreed Activities
 Cost Sharing; Opt-Out
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -31-




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##### 



[****] Opt-Out Notice Maxygen Opt-Out Right [****] [****] [****] [****] [****] Opt-Out Event [****] [****] [****] [****] [****]
 Development of Products for Exclusive Indications Worldwide and for Co-Development
Indications for Outside the Joint Development Territory
 Development for Exclusive Indications
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -32-




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Exclusive Indication Plans [****] [****] provided however
 Co-Development Indications for Outside the Joint Development Territory
 ROW Co-Development Indication Plans [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -33-




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[****] [****] provided however
 Clinical Trials
 Reports
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -34-




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ARTICLE 5
COMMERCIALIZATION
 Commercialization
 General
 Product Commercialization Plans [****] [****]
 Co-Promotion Co-Promotion Option
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -35-




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##### 



Co-Promotion Notice [****] [****] [****] [****] [****] Co-Promot
ion
Product
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -36-




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Co-Promotion Percentage Co-Promotion Percentage [****] [****] [****] [****]
 Co-Promotion Plan
 Co-Promotion Plan
  
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -37-




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Co-Promotion Obligations [****] [****]
 Co-Promotion Coordination
    
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -38-




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Co-Promoting Party is not a Distributor
 Separate Agreement [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -39-




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Maxygen Mark Maxygen Mark
 Costs; Profit Sharing
  -40-




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##### 



Termination [****]
 Reports
 Bundled Products Bundled
Products
 ARTICLE 6
MANUFACTURING, REGULATORY & OTHER MATTERS
 Manufacturing
 Initial Period; Certain General Terms
  
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -41-




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Approved Maxygen CMO
   Supplies Requirement Plan Astellas Requirements
 -42-




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##### 



provided, however,
     -43-




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[****] [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -44-




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Beginning with Initiation of Phase III Clinical Trials and Commercialization
 provided, however
  Bulk Drug Substance Supply
 Exhibit 6.1.3(a)
 -45-




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##### 



[****] [****] [****] provided, however, [****] [****] [****] [****] [****]
  Coordination
   
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -46-




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Transfer of Finished Drug Product Manufacturing Technology Approved Astellas CMO [****]
 Transfer of Bulk Drug Substance Manufacturing Technology
 Bulk Drug Substance for Clinical Supplies
 Delay
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -47-




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[****] No-Fault Cause
 Approaches to Resolve
 Costs New Manufacturer
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -48-




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Existing Manufacturer [****] [****] [****] [****] [****] [****]
 Bulk Drug Substance for Commercial Supplies
 Failure to Supply; Transfer Costs [****] [****] [****] [****] [****] [****] [****] Responsibility Transfer Plan
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -49-




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Price Exceeding [****]% of Net Sales [****] [****] [****] [****] provided
that [****] [****] [****] [****]
 Establishment of Second Source
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -50-




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[****] [****] [****]
 Establishment of a Validated Backup Backup Manufacturer [****]
 Transfer
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -51-




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[****] [****] [****]
 Use of Manufacturing Information provided however
 Regulatory Matters.
 Co-Development Indications.
  [****] [****] [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -52-




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[****] [****]
 Exclusive Indications
   Filings and Correspondence
  
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -53-




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Clinical Safety Reporting; Pharmacovigilance Adverse Drug Reaction
 Cooperation
 -54-




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Transfer of Data, Technology and Regulatory Filings
 Insurance [****] Exhibit 6.4 [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -55-




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ARTICLE 7
EXCLUSIVITY
 Exclusivity of Efforts
 General [****] [****] Exclusivity Period Competing Activities
 Other Uses
 Permitted Activities [****] Permitted Activities
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -56-




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Manufacture
 Post-Effective Date Affiliated Parties Subject Transaction Post-Execution
Affiliate Notifying Party Other Party [****] Separate Program
 Threshold [****] [****]
 Certain Limitations
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -57-




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Divest Divest
 ARTICLE 8
PAYMENTS
 Certain Payments and Sharing
 Technology Access Fee [****]
 Development Milestone Payments
 Sharing of Costs, Net Sales and Profits (Losses) from the Alliance
 Payments; Foreign Exchange The Wall
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -58-




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##### 



Street Journal
 Late Payments The Wall Street Journal [****] [****]
 Taxes; Astellas U.S. Affiliate to Pay Distributable Profit Amounts
 ARTICLE 9
LICENSE GRANTS
 Licenses To Astellas.
 To Perform Preclinical Development and Development provided, however
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -59-




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To Manufacture Products provided, however
 To Commercialize Products
 [****] Direct Country
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -60-




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To the Maxygen Mark provided, however
   -61-




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##### 



Existing Third Party Licenses
 To Maxygen
 To Perform Preclinical Development and Development provided however
 To Manufacture Products provided, however
 No Other Rights
 Licenses of Intellectual Property
 -62-




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##### 



ARTICLE 10
INTELLECTUAL PROPERTY
 Common Interest Disclosures
 Ownership
 Outside the Alliance
 Alliance Technology
 Astellas Independent Inventions Maxygen Independent Inventions Joint Inventions
 -63-




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##### 



Shuffling Improvement
    Patent Matters
 Prosecution and Maintenance of Maxygen Patents provided however
 Exhibit 10.3.1 Core Countries [****] [****] further provided however [thirty (30)] [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -64-




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[****] [****] [****] further provided however [****] [****]
 Prosecution and Maintenance of Joint Patents Joint Patent provided however,
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -65-




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[****] provided however [****] [****] [****] [at its
own expense] provided however [****] [****]
 Cooperation Controlling Party [****] [****]
 Prosecution and Maintenance of Astellas Patents [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -66-




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[****]
 Prosecution and Maintenance Prosecution and
Maintenance
 Patent Term Extensions
 Third Party Technologies
 Third Party Technology Use [****] [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -67-




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Third Party Technology Procedures for the Alliance Third Party License provided however provided, however
 -68-




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##### 



provided however
 Defense and Settlement of Third Party Claims provided however Damages
 Enforcement Competing
Infringing Activities Enforcement Action
 -69-




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Rights to Bring and Control Enforcement Action [****]
 Allocation of Recoveries Recoveries [****] [****] [****] [****]
 Costs
 Trademarks Marks
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -70-




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ARTICLE 11
CONFIDENTIALITY
 Confidentiality; Exceptions Confidential Information
      [****] provided however [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -71-




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Authorized Disclosure [****] Exhibit 11.2 provided, however [****] Walled-Off Programs
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -72-




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Target [****]
 Prior CDA [****] Prior CDA
 Publications
 General Publishing Party Reviewing Party [****] [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -73-




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Publicity
 Confidential Terms Exhibit 11.2 provided however Exhibit 11.5
 Publicity Review
 -74-




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Requesting Party Cooperating Party [****] [****] provided that Exhibit 11.5.2
 Coordination Regarding Required Disclosures
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -75-




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Subsequent Disclosures provided however
 ARTICLE 12
REPRESENTATIONS, WARRANTIES AND COVENANTS;
INDEMNIFICATION
 Mutual Representations, Warranties and Covenants Representing
Party
      -76-




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##### 



Representations, Warranties and Covenants by Maxygen
       Existing Third Party Licenses
 -77-




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##### 



Exhibit 1.50.2
 Representations, Warranties and Covenants by Astellas
   Disclaimer of Warranties
 -78-




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##### 



Indemnification.
 Fault-Based.
 Astellas Indemnitees Losses Claims Fault
 Maxygen
Indemnitees Fault
 No Fault
 Apportionment of Fault
 -79-




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##### 



Claim for Indemnification Indemnified Party Indemnifying Party
 Reduction of Indemnity Payments
 ARTICLE 13
TERM AND TERMINATION
 Term Term
 Termination by Astellas
 For Convenience [****]
 For Adverse Safety/Tox Results
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -80-




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[****] Adverse Safety/Tox Results [****] [****] [****] [****] [****] [****] [****]
 Termination for Breach [****] [****] [****] [****] [****]
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -81-




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[****] [****]
 Cessation of Development and Commercialization
 Termination by Region for Permanent Cessation of all Development and
Commercialization
 Decision or Cessation in Fact; Notice
 Partial Termination
 
 *
    
    Certain information on this page has been omitted and
filed separately with the Securities and Exchange Commission. Confidential
treatment has been requested with respect to the omitted portions. -82-




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Effect of Termination as to a Particular Region
 Partial Termination by Region for Permanent Cessation Regarding Co-Development
Indications.
 Decision or Cessation in Fact; Notice CDI Cessation Notice
 -83-




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Additional Screening for Compounds; Additional Shuffling [****] [****]
 
 *
 -84-




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##### 



[****] [****] [****] unless and until [****] [****]
 Repayment of Maxygen Co-Development Costs [****] The Wall Street Journal [****]
 
 *
 -85-




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##### 



Maxygens Co-Development Indication Costs [****]
 Partial Termination
 
 *
 -86-




---



##### 



Effects of Partial Termination
 Affected Area
  Reverted Compounds provided however Excluded Compounds
  New Libraries Astellas-Selected New Compounds Maxygen-Selected New Compounds [****]
 
 *
 -87-




---



##### 



[****] [****] provided however [****] [****] provided however
  Maxygen Reverted Compound Activities
 
 *
 -88-




---



##### 



Third Party Reverted Compound
Activities
  -89-




---



##### 



General Effects of Expiration or Termination
 Accrued Obligations
 Non-Exclusive Remedy
 General Survival [****]
 *
 -90-




---



##### 



provided however
 Indemnification
 Effects of Certain Terminations
 Ongoing Trials [****]
 
 *
 -91-




---



##### 



Commercialization [****] Agreement Wind-Down Period [****]
 Regulatory Filings [****]
 Technology Licenses
 
 *
 -92-




---



##### 



provided, however
 Marks
 Sublicensees
 Governance [****]
 Transition Assistance [****] provided, however [****] [****] [****]
 
 *
 -93-




---



##### 



[****] [****] [****]
 Return of Materials [****]
 Termination as to a Particular Product
 Effects of Terminations for Maxygens Breach
 
 *
 -94-




---



##### 



Certain Payments upon Termination
 Termination by Astellas Under Section 13.2.1 [****]
 [****] [****] [****]
 [****] [****] [****]
 [****]
 Termination Press Releases [****] [****]
 ARTICLE 14
DISPUTE RESOLUTION
 Disputes
 JSC
 
 *
 -95-




---



##### 



[****] [****]
 CEOs. [****]
 Arbitration [****] [****]
 Intellectual Property Disputes
 Provisional Remedies
 
 *
 -96-




---



##### 



ARTICLE 15
MISCELLANEOUS
 Governing Law
 Assignment
 Limitation on Liability
 Notices [****]
 
 *
 -97-




---



##### 



[****]
 If to Maxygen
 addressed to:
    
    Maxygen, Inc.515 Galveston DriveRedwood City, California 94063USAAttention: Chief Business OfficerTelephone: (650) 298-5300Telecopy: (650) 298-5869with copy to:
    
    Maxygen, Inc.515 Galveston DriveRedwood City, California 94063USAAttention: General CounselTelephone: (650) 298-5300Telecopy: (650) 298-5803and a copy to:
    
    Wilson Sonsini Goodrich & RosatiProfessional Corporation650 Page Mill RoadPalo Alto, CA 94304-1050USAAttention: David W. StevensTelephone: (650) 493-9300Telecopy: (650) 493-6811If to Astellas,addressed to:
    
    Astellas Pharma Inc.3-11, Nihonbashi-Honcho 2-chomeChuo-ku, Tokyo 103-8411JapanAttention: Vice President, Business DevelopmentTelephone: (813) 3244-2500Telecopy: (813) 5203-7164with a copy to:
    
    Astellas Pharma Inc.3-11, Nihonbashi-Honcho 2-chome
 
 *
 -98-




---



##### 



Chuo-ku, Tokyo 103-8411JapanAttention: Vice President, LegalTelephone: (813) 3244-3231Telecopy: (813) 3244-5811
 Waiver
 Severability
 Entire Agreement/Modification
 Non-Solicitation
 Relationship of the Parties
 -99-




---



##### 



Force Majeure [****]
 Third Party Beneficiaries
 Advice of Counsel
 Other Obligations
 Further Assurances
 
 *
 -100-




---



##### 



Compliance with Laws/Other
 Governmental Matters
 Governmental Filings
 License Registrations
 Counterparts
  -101-




---



##### 



IN WITNESS WHEREOF
 MAXYGEN, INC.
    
    
    
    ASTELLAS PHARMA, INC.By:
    
    /s/ Grant Yonehiro
    
    
    
    By:
    
    /s/ Masafumi NogimoriName:
    
    Grant Yonehiro
    
    
    
    Name:
    
    Masafumi NogimoriTitle:
    
    CBO & SVP Development Programs
    
    
    
    Title:
    
    President & CEO
 List of Exhibits:
 
    
    Exhibit 1.5Asia
    
    Exhibit 1.16Existing Compounds
    
    Exhibit 1.17Compound Criteria
    
    Exhibit 1.33Financial Exhibit
    
    Exhibit 1.38Autoimmune Diseases and Conditions
    
    Exhibit 1.46Major Market Countries
    
    Exhibit 1.50.2Maxygen Patents
    
    Exhibit 2.5Initial Committee Membership
    
    Exhibit 3.2Initial Preclinical Development Plan
    
    Exhibit 3.3Clinical Candidate Criteria
    
    Exhibit 6.1.3(a) Commercial Supply Terms and Conditions
    
    Exhibit 6.4Insurance Requirements
    
    Exhibit 10.3.1Core Countries
    
    Exhibit 11.2Existing Agreements
    
    Exhibit 11.5Form Mutual Press Release
    
    Exhibit 11.5.2Press Release Events
    
    Exhibit 12.2.7Existing Third Party Licenses
 -102-




---



##### 



EXHIBIT 1.5
 ASIA
 Asia
 [****]
 
 *
 -1-




---



##### 



EXHIBIT 1.16
 EXISTING COMPOUNDS
  [****]
 
 *
 -1-




---



##### 



EXHIBIT 1.17
 COMPOUND CRITERIA
  1.
    
    [****]greater than or equal to [****], measured under the same conditions using a
[****]2.
    
    Greater than or equal to [****]:
 a. [****]
b. [****]
c. [****]
d. [****]
 3.
    
    Less than or equal to [****]
 
 *
 -1-




---



##### 



EXHIBIT 1.33
 FINANCIAL EXHIBIT
 Financial Exhibit Agreement
    ARTICLE 1
MILESTONE PAYMENTS
 Milestones
 Milestone Payments Milestone
 -1-




---



##### 



Milestone
    
    MilestonePayment for
    
    Payment for[****]
    
    [****]No.
    
    Milestone Event
    
    Indication:
    
    Indication:1.
    
    [****]
    
    $[5,000,000]2.
    
    [****]
    
    $[****]
    
    $[****]3.
    
    [****]
    
    $[****]
    
    $[****]4.
    
    [****]
    
    $[****]
    
    $[****]5.
    
    [****]
    
    [****]
    
    $[****]6.
    
    [****]
    
    $[****]
    
    $[****]7.
    
    [****]
    
    [****]
    
    $[****]8.
    
    [****]
    
    $[****]
    
    $[****]
 Certain Terms
 (a)
    
    [****] shall be deemed to occur upon [****].(b)
    
    [****] shall be deemed to occur on [****].(c)
    
    [****] of a [****]shall be deemed to occur upon the [****].
 [****] [****] [****] [****] [****]% [****] [****]  [****]% [****] [****] [****] [****]
 
 *
 2




---



##### 



Additional Compounds/Products [****]  [****]%
 Timing
  
 *
 3




---



##### 



[****] [****] [****] Congruency Payment Date follows by [****] [****]
 
 *
 4




---



##### 



Discontinued Compounds/Products Discontinued Compound/Product
 Reports and Payments [****] Milestone Achievement Notice [****]
 ARTICLE 2
ROYALTIES
 Royalty Payments
 
 *
 5




---



##### 



Sublicensees Royalty Bearing Territory Royalty Bearing Territory
 Base Royalty Rate Base Royalty Rates
 Aggregate Annual Net Sales of All Products
    
    Base Royalty RatePortion of Aggregate Annual Net Sales less than [****]
Dollars ($[****])
    
    
    [****]
    %Portion of Aggregate Annual Net Sales equal to or
exceeding [****]Dollars ($[****]) up to and including
[****]Dollars ($[****])
    
    
    [****]
    %Portion of Aggregate Annual Net Sales in excess of
[****]Dollars ($[****])
    
    
    [****]
    %
 Aggregate Annual Net Sales [****] [****]
 EXAMPLE
 [****]
 
 *
 6




---



##### 



Certain Additions to Royalties
 [****] [****]
 [****] [****]
   
 *
 7




---



##### 



ADDITIONAL EXAMPLES
 [****]
 [****]
 Royalty Offsets and Reductions; Floor
 Third Party Payments [****] [****] Third Party
Payments [****] [****] [****] [****]
 Generic Competition [****] [****]
 
 *
 8




---



##### 



Generic Competition [****] [****] [****] [****]
 Generic Product ,
 Combination Products
 
 *
 9




---



##### 



Combination Product [****] [****]
 Valid Claim [****] [****]
 Royalty Floor [****] [****]
 Royalty Term
 
 *
 10




---



##### 



Royalty Term
 Royalty Reports [****]
        Timing of Royalty Payments
 
 *
 11




---



##### 



Royalties under Existing In-Licenses Existing In-Licenses Exhibit 10.5
 ARTICLE 3
COSTS AND REVENUE SHARING
 Preclinical Development Costs
 Cost Sharing
 [****] [****] [****] [****]
   
 *
 12




---



##### 



in vivo in vivo
 Initial Preclinical Development Funding
 Disputes Regarding Allocation of Preclinical Development Costs [****] [****] [****] [****]
 
 *
 13




---



##### 



[****] [****] [****] [****]
 Development Costs
 Cost Sharing with respect to Development Prior to Exercise of Maxygen Opt-Out
Right
 [****] [****] [****] [****]
    
 *
 14




---



##### 



Cost Sharing with respect to Development After Exercise of Maxygen Opt-Out
Right
    Opt-Out Product Continuing
Product
 Certain Terms Regarding Phase IV Clinical Trial Costs
 15




---



##### 



Maxygen Phase IV Development Costs Phase IV Carry-Over Amount provided however [****] The Wall Street Journal
 Distributable Profits
 If Maxygen Exercises its Co-Promotion Option
 
 *
 16




---



##### 



[****] [****] [****] [****]
  If Maxygen Does Not Exercise its Co-Promotion Option
 Costs for Commercialization of Products for Exclusive Indications
 Astellas Exclusive Costs
 
 *
 17




---



##### 



ARTICLE 4
REPORTING AND RECONCILIATION
 Principles of Reporting
    Frequency of Reporting
   18




---



##### 



Report
    
    Frequency
    
    Timing of SubmissionActuals
    
    Quarterly
    
    Within [****]days after the
end of the applicable
calendar quarterOne Fiscal Year Forecasts
    
    Semi-annually
    
    By the end of [****]and the
end of [****], respectivelyConsolidation & Variances
    
    Quarterly
    
    Within [****]days after the
end of the applicable
calendar quarter.Final Budgets
    
    Annually
    
    [****]days prior to the
start of the applicable
Fiscal Year (one Fiscal Year)[****]
    
    Annually
    
    [****]days prior to the
start of the applicable
Fiscal Year [****][****]
    
    Annually
    
    [****]days prior to the
start of the applicable
Fiscal Year [****]
   [****]
  
 *
 19




---



##### 



-
    
    actual results for Preclinical Development Costs, Process Development Costs,
Development Costs and Operating Expenses-
    
    forecasts for Preclinical Development Costs, Process Development Costs,
Development Costs and Operating Expenses-
    
    Budgets for Preclinical Development Costs, Process Development Costs,
Development Costs and Operating Expenses-
    
    long range Plans for Preclinical Development Costs, Process Development Costs,
Development Costs and Operating Expenses-
    
    inventory levels-
    
    Gross Sales-
    
    Reserve for Sales Returns and Allowances-
    
    Marketing Costs and Sales Cost-
    
    other financial matters, including each Partys methodologies for determining
costs, actual amounts, forecasts, budgets and long range plans and the results of
applying such methodologies.
 Budgets, Variances and Long Range Plans
  [****] [****] [****] [****] provided however
  
 *
 20




---



##### 



Responsibility for Reporting.
 Party Reports
 Consolidation & Variances Report
 Reconciliation and Settlement of Payments between the Parties
 JPT Determination
 21




---



##### 



Settlement Calculations
 Preclinical Development Costs and Development Costs
 Pre-Launch Operating Expenses for Co-Promotion Products Pre-Launch Costs [****]
 Calculation of Distributable Profits; Reimbursement of Expenses [****]
 
 *
 22




---



##### 



Reimbursement of Operating Expenses
 Settlement of Distributable Profits
 [****] [****] provided however
 Co-Promotion Product Loss provided however [****] The Wall
Street Journal provided however
 
 *
 23




---



##### 



[****] provided however [****] [****] [****]
 Net Settlement Payment
 Timing of Payments [****]
 Disputes Regarding Financial Matters
 Accounting
 
 *
 24




---



##### 



Start of Operations and Effective Accounting Date Termination
   Principles of Reporting
       25




---



##### 



Treatment of Overhead
 ARTICLE 5
DEFINITIONS
 Allocable Overhead
 26




---



##### 



Costs
 Development Costs
   27




---



##### 



Distributable Profits provided however
 Distribution Costs
 External Expenses
 FTE
 28




---



##### 



FTE Costs
 FTE Rate [****] [****] [****] [****]
 Gross Sales
 Interest Rate The Wall Street Journal [****] [****] [****]
 Internal Costs
 
 *
 29




---



##### 



Manufacturing Cost [****] [****] provided however
 Marketing Costs
 
 *
 30




---



##### 



Net Sales
 Operating Expenses
  31




---



##### 



Other Operating Income/Expense
     Preclinical Development Costs in vitro in vivo
 Reserve for Sales Returns and Allowances
 32




---



##### 



Sales Costs
 ARTICLE 6
BOOKS AND RECORDS; AUDITS
 Books and Records
 Audit Rights
 33




---



##### 



[****] [****] [****] [****] [****] [****] [****]
 
 *
 34




---



##### 



EXHIBIT 1.38
 AUTOIMMUNE DISEASES AND CONDITIONS
 [****]
 
 *
 -1-




---



##### 



EXHIBIT 1.46
 MAJOR MARKET COUNTRIES
 
    
    [****]
    
    [****]
    
    [****]
    
    [****]
    
    [****]
    
    [****]
    
    [****]
    
    [****]
 
 *
 -1-




---



##### 



EXHIBIT 1.50.2
 MAXYGEN PATENTS
 [****]
 
 *
 -1-




---



##### 



EXHIBIT 2.5
 INITIAL COMMITTEE MEMBERSHIP
 Joint Steering Committee
 For Astellas:
    
    [To be provided within [****]after the Effective Date]For Maxygen:
    
    [****]
 Joint Program Team
 For Astellas:
    
    [To be provided within [****]after the Effective Date]For Maxygen:
    
    [****]
 
 *
 -1-




---



##### 



EXHIBIT 3.2
 Initial Preclinical Development Plan
 [****]
 
 *
 -1-




---



##### 



EXHIBIT 3.3
 CLINICAL CANDIDATE CRITERIA
  [****]
 
 *
 -1-




---



##### 



EXHIBIT 6.1.3(a)
 COMMERCIAL SUPPLY TERMS AND CONDITIONS
  [****]
 
 *
 -1-




---



##### 



EXHIBIT 6.4
 INSURANCE REQUIREMENTS
 General liability insurance coverage
 [****] [****]
 [****] [****]
 Product liability insurance coverage
 [****] [****]
 [****] [****] [****] [****]
 
 *
 -1-




---



##### 



EXHIBIT 10.3.1
 CORE COUNTRIES
 [****]
 
 *
 -1-




---



##### 



EXHIBIT 11.2
 EXISTING AGREEMENTS
  [****]
 
 *
 -1-




---



##### 



EXHIBIT 11.5
 FORM MUTUAL PRESS RELEASE
 (MAXYGEN LOGO)
    
    (ASTELLAS LOGO)
 For Immediate Release
 Maxygen and Astellas Announce Global Agreement to Develop New
Therapies for Autoimmune Diseases and Transplantation  -Astellas to Receive Rights to Commercialize MAXY-4 CTLA4-Ig Candidates-
 -Maxygen to Receive $10 Million Up-front Payment, Up to $160 Million in Milestone
Payments, Percentage of Sales -
      -1-




---



##### 



(MAXYGEN LOGO)
    
    (ASTELLAS LOGO)
  ®
 About MAXY-4
 TM
 About MolecularBreeding Directed Evolution Platform
  About Maxygen
 www.maxygen.com
 About Astellas




---



##### 



(MAXYGEN LOGO)
    
    (ASTELLAS LOGO)
 ® ®
 Maxygen Forward Looking Statements Disclaimer
    Contact Maxygen:
 michele.boudreau@maxygen.com
 Contact Astellas:




---



##### 



EXHIBIT 11.5.2
 PRESS RELEASE EVENTS
 [****]
 
 *
 -1-




---



##### 



EXHIBIT 12.2.7
 EXISTING THIRD PARTY LICENSES
  [****]
 
 *
 -1-