EXHIBIT A
AGREEMENT REGARDING JOINT FILING
The undersigned, Biotechnology Value Fund, L.P., a Delaware limited
partnership, BVF Inc., a Delaware Corporation, and BVF Partners L.P.,
a Delaware limited partnership, hereby agree and acknowledge that the
amended statement containing the information required by Schedule 13D,
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: October 29, 1996
BIOTECHNOLOGY VALUE FUND, L.P.
By: BVF Partners L.P., its general partner
By: BVF Inc., its general partner
By: /s/ XXXX X. XXXXXXX
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Xxxx X. Xxxxxxx, President
BVF PARTNERS L.P.
By: BVF Inc., its general partner
By: /s/ XXXX X. XXXXXXX
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Xxxx X. Xxxxxxx, President
BVF INC.
By: /s/ XXXX X. XXXXXXX
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Xxxx X. Xxxxxxx, President
