SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* MPM BIOVENTURES II QP LP (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol METABASIS THERAPEUTICS INC [ MBRX ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 09/30/2005
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/30/2005		P		699,659(1)	D	$5.86	4,497,978	I	See footnote(2)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Common Stock Warrant (Right to Buy)	$6.74	09/30/2005		P		244,881(3)		03/29/2006	09/30/2010	Common Stock	244,881	$0.125	244,881	I	See Footnote(3)

1. Name and Address of Reporting Person* MPM BIOVENTURES II QP LP (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM BIOVENTURES II LP (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM BIOVENTURES II GMBH & CO PARALLEL BETEILIGUNGS KG (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM ASSET MANAGEMENT INVESTORS 2000B LLC (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM ASSET MANAGEMENT II LP (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM ASSET MANAGEMENT II LLC (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* GADICKE ANSBERT (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* STEINMETZ MICHAEL (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* WHEELER KURT (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* GALAKATOS NICHOLAS (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 111 HUNTINGTON AVE., 31ST FLOOR (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. The shares were purchased as follows: 471,010 by MPM BioVentures II-QP, L.P. ("BV II QP"), 51,985 by MPM BioVentures II, L.P. ("BV II"), 10,845 by MPM Asset Management Investors 2000B LLC ("AM 2000") and 165,819 by MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG ("BV KG"). MPM Asset Management II, L.P. 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. Luke Evnin, Ansbert Gadicke, Nicholas Galakatos, Michael Steinmetz and Kurt Wheeler are the members of AM II LLC and AM 2000. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.

2. The shares are held as follows: 3,028,085 by BV II QP, 334,131 by BV II, 69,718 by AM 2000 and 1,066,044 by BV KG. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein.

3. The warrants were purchased and are held as follows: 164,854 by BV II QP, 18,195 by BV II, 3,795 by AM 2000 and 58,037 by BV KG. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein.

	By Luke Evnin, manager of MPM Asset Management II LLC, the general partner of MPM Asset Management II, L.P., the general partner of MPM BioVentures II-QP, L.P /s/ Luke Evnin	10/04/2005
	By Luke Evnin, manager of MPM Asset Management II LLC, the general partner of MPM Asset Management II, L.P.,the general partner of MPM BioVentures II, L.P /s/ Luke Evnin	10/04/2005
	By Luke Evnin, member of MPM Asset Management II LLC, the general partner of MPM Asset Management II, L.P., in its capacity as special limited partner of MPM BioVentures GmbH and Co. Parallel-Beteiligungs KG /s/ Luke Evnin	10/04/2005
	By Luke Evnin, manager of MPM Asset Management Investors 2000B LLC /s/ Luke Evnin	10/04/2005
	By Luke Evnin, manager of MPM Asset Management II LLC, the general partner of MPM Asset Management II, L.P. /s/ Luke Evnin	10/04/2005
	By Luke Evnin, manager of MPM Asset Managment II, LLC /s/ Luke Evnin	10/04/2005
	/s/ Ansbert Gadicke	10/04/2005
	/s/ Michael Steinmetz	10/04/2005
	/s/ Kurt Wheeler	10/04/2005
	/s/ Nicholas Galakatos	10/04/2005
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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