MPM Bio Ventures Iii QP SC 13D/A COMBINATORX / MPM BIOVENTURES III-QP ownership change

Exhibit C
JOINT FILING STATEMENT

I, the undersigned, hereby express my agreement that the attached Schedule 13D/A (and any amendments thereto) relating to the Common Stock of CombinatoRx, Incorporated is filed on behalf of each of the undersigned.

Dated: March 16, 2010

MPM BIOVENTURES III, L.P.		MPM BIOVENTURES III-QP, L.P.
By:	MPM BioVentures III GP, L.P., its General Partner	By:	MPM BioVentures III GP, L.P., its General Partner
By:	MPM BioVentures III LLC, its General Partner	By:	MPM BioVentures III LLC, its General Partner
By:	/s/ Luke Evnin	By:	/s/ Luke Evnin
	Name: Luke Evnin Title:   Series A Member		Name: Luke Evnin Title:   Series A Member
MPM BIOVENTURES III PARALLEL FUND, L.P.		MPM BIOVENTURES III GMBH & CO. BETEILIGUNGS KG
By:	MPM BioVentures III GP, L.P., its General Partner	By:	MPM BioVentures III GP, L.P., in its capacity as the Managing Limited Partner
By:	MPM BioVentures III LLC, its General Partner	By:	MPM BioVentures III LLC, its General Partner
By:	/s/ Luke Evnin	By:	/s/ Luke Evnin
	Name: Luke Evnin Title:   Series A Member		Name: Luke Evnin Title:   Series A Member
MPM ASSET MANAGEMENT INVESTORS 2003 BVIII LLC		MPM BIOVENTURES III GP, L.P.
By:	/s/ Luke Evnin	By:	MPM BioVentures III LLC, its General Partner
	Name: Luke Evnin Title:   Manager
		By:	/s/ Luke Evnin
			Name: Luke Evnin Title:   Series A Member
MPM BIOVENTURES III LLC		MPM ASSET MANAGEMENT LLC
By:	/s/ Luke Evnin	By:	/s/ Luke Evnin
	Name: Luke Evnin Title:   Series A Member		Name: Luke Evnin Title:   Member
	/s/ Luke Evnin		/s/ Ansbert Gadicke
	Luke Evnin		Ansbert Gadicke
	/s/ Nicholas Galakatos		/s/ Michael Steinmetz
	Nicholas Galakatos		Michael Steinmetz
	/s/ Kurt Wheeler		/s/ Nicholas Simon III
	Kurt Wheeler		Nicholas Simon III
	/s/ Dennis Henner
	Dennis Henner