EXHIBIT A AGREEMENT REGARDING JOINT FILING -------------------------------- The undersigned, Biotechnology Value Fund, L.P., a Delaware limited partnership, and BVF Partners L.P., a Delaware limited partnership, and BVF Inc., a Delaware corporation,...Joint Filing Agreement • May 5th, 1997 • Biotechnology Value Fund L P Et Al • Investment advice
The undersigned, Biotechnology Value Fund, L.P., a Delaware limited partnership, and BVF Partners L.P., a Delaware limited partnership, and BVF Inc., a Delaware corporation, hereby agree and acknowledge that the Amendment 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 further amendments or supplements thereto shall also be filed on behalf of each of them.
