EX-1 3 a2070474zex-1.htm EXHIBIT 1 Prepared by MERRILL CORPORATION
QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 1

AGREEMENT REGARDING JOINT FILING

        The undersigned, Biotechnology Value Fund, L.P., a Delaware limited partnership, Biotechnology Value Fund II, L.P., a Delaware limited partnership, BVF Investments, L.L.C., a Delaware limited liability company, BVF Partners L.P., a Delaware limited partnership, and BVF Inc., a Delaware corporation, hereby agree and acknowledge that the information required by the Amendment to Schedule 13G, to which this Agreement is attached as an exhibit, is filed on behalf of each of them. The undersigned further agree that any amendments or supplements thereto shall also be filed on behalf of each of them.

Dated: February 14, 2002

BIOTECHNOLOGY VALUE FUND, L.P.

By:

 

BVF Partners L.P., its general partner

 

 

By:

 

BVF Inc., its general partner

 

 

 

 

By:

 

/s/  
MARK N. LAMPERT      
Mark N. Lampert
President

BIOTECHNOLOGY VALUE FUND II, L.P.

By:

 

BVF Partners L.P., its general partner

 

 

By:

 

BVF Inc., its general partner

 

 

 

 

By:

 

/s/  
MARK N. LAMPERT      
Mark N. Lampert
President

BVF INVESTMENTS, L.L.C.

By:

 

BVF Partners L.P., its manager

 

 

By:

 

BVF Inc., its general partner

 

 

 

 

By:

 

/s/  
MARK N. LAMPERT      
Mark N. Lampert
President

BVF PARTNERS L.P.

By:

 

BVF Inc., its general partner

 

 

By:

 

/s/  
MARK N. LAMPERT      
Mark N. Lampert
President

BVF INC.

By:

 

/s/  
MARK N. LAMPERT      
Mark N. Lampert
President



QuickLinks

AGREEMENT REGARDING JOINT FILING