Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
MPM BIOVENTURES II QP LP
   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)
(Last)
(First)
(Middle)
C/O MPM ASSET MANAGEMENT, 200 CLARENDON STREET, 54TH FLOOR		 3. Date of Earliest Transaction (Month/Day/Year)
04/16/2008
(Street)

BOSTON, MA 02116		 4. If Amendment, Date 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
(City)
(State)
(Zip)
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 04/16/2008   X   244,881 (2) A $ 2.34 4,742,859 I See footnote (3)
Common Stock 04/16/2008   P   71,866 (5) A $ 2.34 4,814,725 I See footnote (6)

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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 Underlying Securities
(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 of Derivative Security: 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 04/16/2008   J(1)     244,881 (2) 03/29/2006 09/30/2010 Common Stock 244,881 $ 0.125 0 I See Footnote (4)
Common Stock Warrant (Right to Buy) $ 2.34 04/16/2008   J(1)   244,881 (2)   04/16/2008 04/16/2008 Common Stock 244,881 $ 0 244,881 I See Footnote (2)
Common Stock Warrant (Right to Buy) $ 2.34 04/16/2008   X     244,881 (2) 04/16/2008 04/16/2008 Common Stock 244,881 $ 0 0 I See Footnote (4)
Common Stock Warrant (Right to Buy) $ 2.69 04/16/2008   P   70,538 (7)   04/16/2008 04/16/2013 Common Stock 70,538 $ 0.125 70,538 I See Footnote (7)

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
MPM BIOVENTURES II QP LP
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    
MPM BIOVENTURES II LP
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    
MPM BIOVENTURES GMBH & CO PARALLEL BETEILIGUNGS KG
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    
MPM ASSET MANAGEMENT INVESTORS 2000B LLC
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    
MPM ASSET MANAGEMENT II LP
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    
MPM ASSET MANAGEMENT II LLC
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    
GADICKE ANSBERT
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    
STEINMETZ MICHAEL
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    
WHEELER KURT
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    
GALAKATOS NICHOLAS
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116		     X    

Signatures

 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   04/18/2008
**Signature of Reporting Person Date
 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   04/18/2008
**Signature of Reporting Person Date
 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   04/18/2008
**Signature of Reporting Person Date
 By Luke Evnin, manager of MPM Asset Management Investors 2000B LLC /s/ Luke Evnin   04/18/2008
**Signature of Reporting Person Date
 By Luke Evnin, manager of MPM Asset Management II LLC, the general partner of MPM Asset Management II, L.P. /s/ Luke Evnin   04/18/2008
**Signature of Reporting Person Date
 By Luke Evnin, manager of MPM Asset Managment II, LLC /s/ Luke Evnin   04/18/2008
**Signature of Reporting Person Date
 /s/ Ansbert Gadicke   04/18/2008
**Signature of Reporting Person Date
 /s/ Michael Steinmetz   04/18/2008
**Signature of Reporting Person Date
 /s/ Kurt Wheeler   04/18/2008
**Signature of Reporting Person Date
 /s/ Nicholas Galakatos   04/18/2008
**Signature of Reporting Person Date

Explanation of Responses:

* 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).
(1) Represents the reduction in the exercise price of such warrants from $6.74 to $2.34.
(2) The warrants were held and exercised as follows: 164,854 by MPM BioVentures II-QP, L.P. ("BV II QP"), 18,195 by MPM BioVentures II, L.P. ("BV II"), 3,795 by MPM Asset Management Investors 2000B LLC ("AM 2000") and 58,037 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.
(3) The shares are held as follows: 3,192,939 by BV II QP, 352,326 by BV II, 73,513 by AM 2000 and 1,124,081 by BV KG. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.
(4) No securities owned
(5) The shares were purchased as follows: 48,379 by BV II QP, 5,340 by BV II, 1,115 by AM 2000 and 17,032 by BV KG. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.
(6) The shares are held as follows: 3,241,318 by BV II QP, 357,666 by BV II, 74,628 by AM 2000 and 1,141,113 by BV KG. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.
(7) The warrants were purchased and are held as follows: 47,485 by BV II QP, 5,241 by BV II, 1,094 by AM 2000 and 16,718 by BV KG. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.

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