**Exhibit 10.36**

[ENTREMEDLetterhead] 
| Affymax, Inc.  4001 Miranda Avenue  Palo Alto, California 94304 | February 23, 2007                         |
|-----------------------------------------------------------------|-------------------------------------------|
| Attn:                                                           | Chris Dammann   VP, Business Development  |
|                                                            |                                      |
|  Re:                                                       | **Seventh Extension of Letter Agreement** |
|                                                                 |                                           |  |

Dear Chris:

        Iam writing with reference to the Letter Agreement between Affymax, Inc. (“Affymax”)and EntreMed, Inc. (“EntreMed”) dated as of September 20, 2004 (togetherwith each of the exhibits thereto, as amended, the “Letter Agreement”) and therelated First Extension Letter dated as of August 23, 2005 between Affymaxand EntreMed (the “First Extension Letter”), pursuant to which EntreMed andAffymax agreed to extend the Term of the Letter Agreement to December 31,2005, and the subsequent Second Extension Letter dated as of December 19,2005 between Affymax and EntreMed (the “Second Extension Letter”), pursuant towhich EntreMed and Affymax agreed to further extend the Term of the LetterAgreement to February 28, 2006, and the subsequent Third Extension Letterdated as of February 28, 2006 between Affymax and EntreMed (the “ThirdExtension Letter”), pursuant to which EntreMed and Affymax agreed to furtherextend the Term of the Letter Agreement to May 31, 2006, and thesubsequent Fourth Extension Letter dated as of May 24, 2006 betweenAffymax and EntreMed (the “Fourth Extension Letter”), pursuant to whichEntreMed and Affymax agreed to further extend the Term of the Letter Agreementto August 31, 2006, and the subsequent Fifth Extension Letter dated as ofAugust 23, 2006 between Affymax and EntreMed (the “Fifth Extension Letter”),pursuant to which EntreMed and Affymax agreed to further extend the Term of theLetter Agreement to November 30, 2006 and the subsequent Sixth Extensionletter dated as of November 27, 2006 between Affymax and EntreMed (the “SixthExtension Letter”), pursuant to which EntreMed and Affymax agreed to furtherextend the Term of the Letter Agreement to February 28, 2007.  All capitalized terms used but not definedherein shall have the meaning given to such terms in the Letter Agreement.

        Asboth parties would like to continue the Research Collaboration under the LetterAgreement, pending our current negotiations relating to a Co-DevelopmentAgreement, the Term of the Letter Agreement is agreed to be further extended toMay 31, 2007. Both Affymax and EntreMed acknowledge and agree that, except asotherwise set forth in herein, all terms and conditions of the LetterAgreement, the First Extension Letter, the Second Extension Letter, the ThirdExtension Letter, the Fourth Extension Letter, the Fifth Extension Letter andthe Sixth Extension Letter would remain unchanged and in full force and effect.

        Pleaseconfirm your agreement to extend the Term of the Letter Agreement (including, withoutlimitation, the period to enter into a Co-Development Agreement) to May 31,2007, by countersigning this Letter and returning the countersigned letter toEntreMed. 
|                      | Very truly yours, |                                                            |
|----------------------|-------------------|-----------------------------------------------------------------|
|                 |              |                                                            |
|                 | EntreMed, Inc.    |                                                            |
|                 |              |                                                            |
|                 | By:               | /s/  MARC CORRADO                                     |
|                 |              | Name: Marc Corrado

Title: Vice President Corporate Development |
| ACCEPTED AND AGREED: |              |                                                            |
|                 |              |                                                            |
| Affymax, Inc.        |              |                                                            |
|                      |                   |                                                                 |  |

 

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| By:    |   | /s/  CHRIS DAMMANN |   |
|--------|--------|------------------------------|--------|
|   |   | Name:  Title:  Date:         |

EntreMed, Inc. / 9640 Medical Center Drive /Rockville, MD 20850240.864.2600 phone / 240.864.2601 fax

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