EXHIBIT A JOINT FILING AGREEMENT
EXHIBIT A
In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the
undersigned agree to the joint filing on behalf of each of them of a statement on Schedule 13G
(including amendments thereto) with respect to the Common Stock of Affymax, Inc. and further agree
that this agreement be included as an exhibit to such filing. Each party to the agreement
expressly authorizes each other party to file on its behalf any and all amendments to such
statement. Each party to this agreement agrees that this joint filing agreement may be signed in
counterparts.
In evidence whereof, the undersigned have caused this Agreement to be executed on their behalf
this 11th day of February, 2009.
| MPM BIOVENTURES II, L.P. | MPM BIOVENTURES II-QP, L.P. | |||||||||
By:
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MPM Asset Management II, L.P., its General Partner |
By: | MPM Asset Management II, L.P., its General Partner |
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By:
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MPM Asset Management II LLC, its General Partner |
By: | MPM Asset Management II LLC, its General Partner |
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By:
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/s/ Xxxx X. Xxxxx | By: | /s/ Xxxx X. Xxxxx | |||||||
| Name: Xxxx X. Xxxxx | Name: Xxxx X. Xxxxx | |||||||||
| Title: Investment Manager | Title: Investment Manager | |||||||||
| MPM BIOVENTURES GMBH & CO. PARALLEL- | MPM ASSET MANAGEMENT INVESTORS 2001 LLC | |||||||||
| BETEILIGUNGS KG | ||||||||||
By:
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MPM Asset Management II LP, in its capacity as the Special Limited Partner | By: | /s/ Xxxx X. Xxxxx | |||||||
| Name: Xxxx X. Xxxxx | ||||||||||
| Title: Investment Manager | ||||||||||
By:
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MPM Asset Management II LLC, its General Partner | |||||||||
By:
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/s/ Xxxx X. Xxxxx | |||||||||
| Name: Xxxx X. Xxxxx | ||||||||||
| Title: Investment Manager | ||||||||||
| MPM ASSET MANAGEMENT II LP | MPM ASSET MANAGEMENT II LLC | |||||||||
By:
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MPM Asset Management II LLC, its General Partner | |||||||||
By:
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/s/ Xxxx X. Xxxxx | By:
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/s/ Xxxx X. Xxxxx | |||||||
| Name: Xxxx X. Xxxxx | Name: Xxxx X. Xxxxx | |||||||||
| Title: Investment Manager | Title: Investment Manager | |||||||||
| MPM BIOVENTURES STRATEGIC FUND, L.P. | MPM BIOVENTURES III GP, L.P. | |||||||||
By:
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MPM BioVentures III GP, L.P., its General Partner | By: | MPM BioVentures III LLC, its General Partner |
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By:
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MPM BioVentures III LLC, its General Partner |
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By:
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/s/ Xxxx X. Xxxxx | By: | /s/ Xxxx X. Xxxxx | |||||||
| Name: Xxxx X. Xxxxx | Name: Xxxx X. Xxxxx | |||||||||
| Title: Series A Member | Title: Investment Manager | |||||||||
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| MPM BIOVENTURES III LLC | ||||||||||
By:
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/s/ Xxxx X. Xxxxx | By: | /s/ Xxxxxxx Xxxxxxx | |||||||
| Name: Xxxx X. Xxxxx | Xxxxxxx Xxxxxxx | |||||||||
| Title: Series A Member | ||||||||||
By:
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/s/ Xxxx X. Xxxxx | By: | /s/ Xxxxxxxx Xxxxxxxxx | |||||||
| Xxxx X. Xxxxx | Xxxxxxxx Xxxxxxxxx | |||||||||
By:
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/s/ Xxxxxxx Xxxxxxxxx | By: | /s/ Xxxx Xxxxxxx | |||||||
| Xxxxxxx Xxxxxxxxx | Xxxx Xxxxxxx | |||||||||
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