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Exhibit 1

JOINT FILING AGREEMENT

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree, as of August 14, 2007, that only one statement containing the information required by Schedule 13G, and each amendment thereto, need be filed with respect to the ownership by each of the undersigned of shares of Common Stock of Curis, Inc.. and such statement to which this Joint Filing Agreement is attached as Exhibit 1 is filed on behalf of each of the undersigned.

RA CAPITAL BIOTECH FUND, L.P.
By:	RA Capital Management, LLC General Partner
By:	/s/ Richard H. Aldrich
Richard H. Aldrich
Manager
RA CAPITAL BIOTECH FUND II, L.P.
By:	RA Capital Management, LLC General Partner
By:	/s/ Richard H. Aldrich
Richard H. Aldrich
Manager
RA CAPITAL MANAGEMENT, LLC
By:	/s/ Richard H. Aldrich
Richard H. Aldrich
Manager
RICHARD H. ALDRICH
/s/ Richard H. Aldrich
PETER KOLCHINSKY
/s/ Peter Kolchinsky