Edgar Filing: AFFYMAX INC

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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. 4)*

AFFYMAX, INC.

(Name of Issuer)

Common Stock
(Title of Class of Securities)

00826A 10 9
(CUSIP Number)

December 31, 2009
(Date of Event Which Requires Filing of This Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

	o		Rule 13d-1(b)

	o		Rule 13d-1(c)

	þ		Rule 13d-1(d)

The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS MPM BioVentures II, L.P.


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

		5	SOLE VOTING POWER

NUMBER OF			109,213

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			0

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			109,213

WITH:		8	SHARED DISPOSITIVE POWER

			0

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	109,213

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	0.6%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	PN

Page 2 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS MPM BioVentures II-QP, L.P.


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

		5	SOLE VOTING POWER

NUMBER OF			989,697

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			0

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			989,697

WITH:		8	SHARED DISPOSITIVE POWER

			0

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	989,697

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	5.2%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	PN

Page 3 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Germany

		5	SOLE VOTING POWER

NUMBER OF			348,491

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			0

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			348,491

WITH:		8	SHARED DISPOSITIVE POWER

			0

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	348,491

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	1.8%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	PN

Page 4 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS MPM Asset Management Investors 2001 LLC


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

		5	SOLE VOTING POWER

NUMBER OF			20,548

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			0

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			20,548

WITH:		8	SHARED DISPOSITIVE POWER

			0

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	20,548

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	0.1%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	OO

Page 5 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS MPM BioVentures Strategic Fund, L.P.


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

		5	SOLE VOTING POWER

NUMBER OF			132,520

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			0

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			132,520

WITH:		8	SHARED DISPOSITIVE POWER

			0

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	132,520

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	0.7%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	PN

Page 6 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS MPM Asset Management II, L.P.


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			1,447,401*

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			1,447,401*

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	1,447,401*

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	7.6%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	PN


*		The shares are held as follows: 989,697 by MPM BioVentures II-QP, L.P. (“BV II QP”); 109,213 by MPM BioVentures II, L.P. (“BV II”); and 348,491 by MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG (“BV KG”). The Reporting Person is the direct general partner of BV II QP, BV II and BV KG.

Page 7 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS MPM Asset Management II LLC


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			1,447,401*

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			1,447,401*

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	1,447,401*

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	7.6%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	OO


*		The shares are held as follows: 989,697 by BV II QP; 109,213 by BV II; and 348,491 by BV KG. The Reporting Person is the indirect general partner of BV II QP, BV II and BV KG.

Page 8 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS MPM BioVentures III GP, L.P.


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			132,520*

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			132,520*

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	132,520*

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	0.7%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	PN


*		The shares are held by MPM BioVentures Strategic Fund, L.P. (“MPM SF”). The Reporting Person is the direct general partner of MPM SF.

Page 9 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS MPM BioVentures III LLC


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			132,520*

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			132,520*

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	132,520*

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	0.7%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	OO


*		The shares are held by MPM SF. The Reporting Person is the indirect general partner of MPM SF.

Page 10 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS Ansbert Gadicke


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	United States

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			1,600,469*

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			1,600,469*

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	1,600,469*

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	8.4%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	IN

* The shares are held as follows: 989,697 by BV II QP; 109,213 by BV II; 20,548 by MPM Asset Management Investors 2001 LLC (“AM 2001”); 348,491 by BV KG; and 132,520 by MPM SF. MPM Asset Management II, L.P. (“AM LP”) and MPM Asset Management II LLC (“AM II LLC”) are the direct and indirect general partners of BV II QP, BV II and BV KG. MPM BioVentures III GP, L.P. (“BV III GP”) and MPM BioVentures III LLC (“BV III LLC”) are the direct and indirect general partners of MPM SF. The Reporting Person is an investment manager of AM II LLC and AM 2001 and a Series A member of BV III LLC. The Reporting Person disclaims beneficial ownership of all such shares except to the extent of his proportionate pecuniary interests therein.

Page 11 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS Luke Evnin


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	United States

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			1,600,469*

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			1,600,469*

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	1,600,469*

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	8.4%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	IN

* The shares are held as follows: 989,697 by BV II QP; 109,213 by BV II; 20,548 by AM 2001; 348,491 by BV KG; and 132,520 by MPM SF. AM LP and AM II LLC are the direct and indirect general partners of BV II QP, BV II and BV KG. BV III GP and BV III LLC are the direct and indirect general partners of MPM SF. The Reporting Person is an investment manager of AM II LLC and AM 2001 and a Series A member of BV III LLC. The Reporting Person disclaims beneficial ownership of all such shares except to the extent of his proportionate pecuniary interests therein.

Page 12 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS Nicholas Galakatos


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	United States

		5	SOLE VOTING POWER

NUMBER OF			32,708*

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			1,600,469**

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			32,708*

WITH:		8	SHARED DISPOSITIVE POWER

			1,600,469**

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	1,633,117* **

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	8.5%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	IN

* Includes 13,958 shares issuable pursuant to options exercisable within 60 days of December 31, 2009.

** The shares are held as follows: 989,697 by BV II QP; 109,213 by BV II; 20,548 by AM 2001; 348,491 by BV KG; and 132,520 by MPM SF. AM LP and AM II LLC are the direct and indirect general partners of BV II QP, BV II and BV KG. BV III GP and BV III LLC are the direct and indirect general partners of MPM SF. The Reporting Person is an investment manager of AM II LLC and AM 2001 and a Series A member of BV III LLC. The Reporting Person disclaims beneficial ownership of all such shares except to the extent of his proportionate pecuniary interests therein.

Page 13 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS Michael Steinmetz


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	United States

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			1,600,469*

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			1,600,469*

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	1,600,469*

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	8.4%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	IN

Page 14 of 23


CUSIP No.		00826A 10 9


1	NAME OF REPORTING PERSONS Kurt Wheeler


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) þ

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	United States

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			1,600,469*

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			1,600,469*

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	1,600,469*

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	8.4%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	IN

Page 15 of 23

The following constitutes Amendment No. 4 to the Schedule 13G previously filed by the undersigned with the Securities and Exchange Commission on February 12, 2007, as subsequently amended by Amendment No. 1 filed on February 12, 2008, amendment No. 2 filed on February 12, 2009 and Amendment No. 3 filed on February 16, 2010 (as so amended, the “Schedule 13G/A”). The Schedule 13G/A is being filed to included 18,750 shares of the Issuer’s Common Stock held by Nicholas Galakatos which was inadvertently left off of the original Schedule 13G.

Item 1.

	(a)		Name of Issuer

			Affymax, Inc.

	(b)		Address of Issuer’s Principal Executive Offices
			4001 Miranda Avenue
			Palo Alto, CA 94304

Item 2.

(a)

Name of Person Filing

MPM BioVentures II, LP

MPM BioVentures II-QP, L.P.

MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG

MPM Asset Management Investors 2001 LLC

MPM BioVentures Strategic Fund, L.P.

MPM Asset Management II, L.P.

MPM Asset Management II LLC

MPM BioVentures III GP, L.P.

MPM BioVentures III LLC

Ansbert Gadicke

Luke Evnin

Nicholas Galakatos

Michael Steinmetz

Kurt Wheeler

(b)

Address of Principal Business Office or, if none, Residence

c/o MPM Capital L.P.

The John Hancock Tower

200 Clarendon Street, 54^th Floor

Boston, MA 02116

(c)

Citizenship

All entities were organized in Delaware except MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG, which was organized in Germany. The individuals are all United States citizens.

(d)

Title of Class of Securities

Common Stock

(e)

CUSIP Number

00826A 10 9


Item 3.		If this statement is filed pursuant to §§240.13d-1(b), or 240.13d-2(b) or (c), check whether the person filing is a:

Not applicable

Page 16 of 23

Item 4. Ownership

(a)

Amount Beneficially Owned:


MPM BioVentures II, L.P.	109,213
MPM BioVentures II-QP, L.P.	989,697
MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG	348,491
MPM Asset Management Investors 2001 LLC	20,548
MPM BioVentures Strategic Fund, L.P.	132,520
MPM Asset Management II, L.P.	1,447,401	(1)
MPM Asset Management II LLC	1,447,401	(1)
MPM BioVentures III GP, L.P.	132,520	(2)
MPM BioVentures III LLC	132,520	(2)
Ansbert Gadicke	1,600,469	(3)
Luke B. Evnin	1,600,469	(3)
Nicholas Galakatos	1,633,177	(3)(4)
Michael Steinmetz	1,600,469	(3)
Kurt Wheeler	1,600,469	(3)

Percent of Class:


MPM BioVentures II, L.P.	0.6	%
MPM BioVentures II-QP, L.P.	5.2	%
MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG	1.8	%
MPM Asset Management Investors 2001 LLC	0.1	%
MPM BioVentures Strategic Fund, L.P.	0.7	%
MPM Asset Management II, L.P.	7.6	%
MPM Asset Management II LLC	7.6	%
MPM BioVentures III GP, L.P.	0.7	%
MPM BioVentures III LLC	0.7	%
Ansbert Gadicke	8.4	%
Luke B. Evnin	8.4	%
Nicholas Galakatos	8.5	%
Michael Steinmetz	8.4	%
Kurt Wheeler	8.4	%

(b)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote


MPM BioVentures II, L.P.			109,213
MPM BioVentures II-QP, L.P.			989,697
MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG			348,491
MPM Asset Management Investors 2001 LLC			20,548
MPM BioVentures Strategic Fund, L.P.			132,520
MPM Asset Management II, L.P.			0

Page 17 of 23


MPM Asset Management II LLC	0
MPM BioVentures III GP, L.P.	0
MPM BioVentures III LLC	0
Ansbert Gadicke	0
Luke B. Evnin	0
Nicholas Galakatos	32,708	(4)
Michael Steinmetz	0
Kurt Wheeler	0

(ii)

Shared power to vote or to direct the vote


MPM BioVentures II, L.P.	0
MPM BioVentures II-QP, L.P.	0
MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG	0
MPM Asset Management Investors 2001 LLC	0
MPM BioVentures Strategic Fund L.P.	0
MPM Asset Management II, L.P.	1,447,401	(1)
MPM Asset Management II LLC	1,447,401	(1)
MPM BioVentures III GP, L.P.	132,520	(2)
MPM BioVentures III LLC	132,520	(2)
Ansbert Gadicke	1,600,469	(3)
Luke B. Evnin	1,600,469	(3)
Nicholas Galakatos	1,600,469	(3)
Michael Steinmetz	1,600,469	(3)
Kurt Wheeler	1,600,469	(3)

(iii)

Sole power to dispose or to direct the disposition of


MPM BioVentures II, LP	109,213
MPM BioVentures II-QP, L.P.	989,697
MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG	348,491
MPM Asset Management Investors 2001 LLC	20,548
MPM BioVentures Strategic Fund, L.P.	132,520
MPM Asset Management II, L.P.	0
MPM Asset Management II LLC	0
MPM BioVentures III GP, L.P.	0
MPM BioVentures III LLC	0
Ansbert Gadicke	0
Luke Evnin	0
Nicholas Galakatos	32,708	(4)
Michael Steinmetz	0
Kurt Wheeler	0

Page 18 of 23

(iv)

Shared power to dispose or to direct the disposition of


MPM BioVentures II, LP	0
MPM BioVentures II-QP, L.P.	0
MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG	0
MPM Asset Management Investors 2001 LLC	0
MPM BioVentures Strategic Fund L.P.	0
MPM Asset Management II, L.P.	1,447,401	(1)
MPM Asset Management II LLC	1,447,401	(1)
MPM BioVentures III GP, L.P.	132,520	(2)
MPM BioVentures III LLC	132,520	(2)
Ansbert Gadicke	1,600,469	(3)
Luke B. Evnin	1,600,469	(3)
Nicholas Galakatos	1,600,469	(3)
Michael Steinmetz	1,600,469	(3)
Kurt Wheeler	1,600,469	(3)


(1)		The shares are held as follows: 989,697 by BV II QP; 109,213 by BV II; and 348,491 by BV KG. AM LP and AM IILLC are the direct and indirect general partners of BV II QP, BV II and BV KG.

(2)		The shares are held by MPM SF. BV III GP and BV III LLC are the direct and indirect general partners of MPM SF.

(3)		The shares are held as follows: 989,697 by BV II QP; 109,213 by BV II; 20,548 by AM 2001; 348,491 by BV KG; and 132,520 by MPM SF. AM LP and AM II LLC are the direct and indirect general partners of BV II QP, BV II and BV KG. BV III GP and BV III LLC are the direct and indirect general partners of MPM SF. The Reporting Person is a managing member of AM II LLC and AM 2001 and BV III LLC. The Reporting Person disclaims beneficial ownership of all such shares except to the extent of his proportionate pecuniary interests therein.

(4)		Includes 13,958 shares issuable upon exercise of options within 60 days of December 31, 2009.

Item 5. Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following o.

Item 6. Ownership of More than Five Percent on Behalf of Another Person

Not Applicable


Item 7.		Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person.

Not Applicable

Item 8. Identification and Classification of Members of the Group

Not Applicable

Item 9. Notice of Dissolution of a Group

Not Applicable

Item 10. Certification

Not Applicable

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: March 2, 2010


MPM BIOVENTURES II, L.P.		MPM BIOVENTURES II-QP, L.P.

By:	MPM Asset Management II, L.P.,	By:	MPM Asset Management II, L.P.,
	its General Partner		its General Partner

By:	MPM Asset Management II LLC,	By:	MPM Asset Management II LLC,
	its General Partner		its General Partner

By:	/s/ Luke B. Evnin	By:	/s/ Luke B. Evnin

	Name: Luke B. Evnin		Name: Luke B. Evnin
	Title: Investment Manager		Title: Investment Manager

MPM BIOVENTURES GMBH & CO. PARALLEL-BETEILIGUNGS KG		MPM ASSET MANAGEMENT INVESTORS 2001 LLC

By:	MPM Asset Management II LP, in its capacity as the Special Limited Partner	By:	/s/ Luke B. Evnin

			Name: Luke B. Evnin
			Title: Investment Manager

By:	MPM Asset Management II LLC,
	its General Partner

By:	/s/ Luke B. Evnin

	Name: Luke B. Evnin
	Title: Investment Manager

MPM ASSET MANAGEMENT II L.P.		MPM ASSET MANAGEMENT II LLC

By:	MPM Asset Management II LLC,
	its General Partner

By:	/s/ Luke B. Evnin	By:	/s/ Luke B. Evnin

	Name: Luke B. Evnin		Name: Luke B. Evnin
	Title: Investment Manager		Title: Investment Manager

MPM BIOVENTURES STRATEGIC FUND, L.P.		MPM BIOVENTURES III GP, L.P.

By:	MPM BioVentures III GP, L.P.,	By:	MPM BioVentures III LLC,
	its General Partner		its General Partner

By:	MPM BioVentures III LLC,
	its General Partner	By:	/s/ Luke B. Evnin

			Name: Luke B. Evnin
By:	/s/ Luke B. Evnin		Title: Series A Member

	Name: Luke B. Evnin
	Title: Series A Member

Page 20 of 23



MPM BIOVENTURES III LLC

By:	/s/ Luke B. Evnin	/s/ Ansbert Gadicke

	Name: Luke B. Evnin	Ansbert Gadicke
	Title: Series A Member

	/s/ Luke B. Evnin	/s/ Nicholas Galaktos

	Luke B. Evnin	Nicholas Galakatos

	/s/ Michael Steinmetz	/s/ Kurt Wheeler

	Michael Steinmetz	Kurt Wheeler

EXHIBITS

A: Joint Filing Agreement

Page 21 of 23

EXHIBIT A

JOINT FILING AGREEMENT

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 2^nd day of March, 2010.


MPM BIOVENTURES II, L.P.
		MPM BIOVENTURES II-QP, L.P.
By:	MPM Asset Management II, L.P.,
	its General Partner	By:	MPM Asset Management II, L.P.,
			its General Partner
By:	MPM Asset Management II LLC,
	its General Partner	By:	MPM Asset Management II LLC,
			its General Partner
By:	/s/ Luke B. Evnin Name: Luke B. Evnin	By:	/s/ Luke B. Evnin Name: Luke B. Evnin
	Title: Investment Manager		Title: Investment Manager

MPM BIOVENTURES GMBH & CO. PARALLEL-BETEILIGUNGS KG		MPM ASSET MANAGEMENT INVESTORS 2001 LLC

By:	MPM Asset Management II LP, in its capacity as the Special Limited Partner	By:	/s/ Luke B. Evnin
			Name: Luke B. Evnin
By:	MPM Asset Management II LLC, its General Partner		Title: Investment Manager

By:	/s/ Luke B. Evnin

	Name: Luke B. Evnin
	Title: Investment Manager

MPM ASSET MANAGEMENT II L.P.		MPM ASSET MANAGEMENT II LLC

By:	MPM Asset Management II LLC, its General Partner

By:	/s/ Luke B. Evnin	By:	/s/ Luke B. Evnin

	Name: Luke B. Evnin		Name: Luke B. Evnin
	Title: Investment Manager		Title: Investment Manager

MPM BIOVENTURES STRATEGIC FUND, L.P.		MPM BIOVENTURES III GP, L.P.

By:	MPM BioVentures III GP, L.P.,	By:	MPM BioVentures III LLC,
	its General Partner		its General Partner

By:	MPM BioVentures III LLC, its General Partner	By:	/s/ Luke B. Evnin
			Name: Luke B. Evnin
By:	/s/ Luke B. Evnin		Title: Series A Member
	Name: Luke B. Evnin
	Title: Series A Member

Page 22 of 23


MPM BIOVENTURES III LLC

By:	/s/ Luke B. Evnin	/s/ Ansbert Gadicke
	Name: Luke B. Evnin	Ansbert Gadicke
	Title: Series A Member

	/s/ Luke B. Evnin	/s/ Nicholas Galaktos

	Luke B. Evnin	Nicholas Galakatos

	/s/ Michael Steinmetz	/s/ Kurt Wheeler

	Michael Steinmetz	Kurt Wheeler

Page 23 of 23