Stephen R. Seiler

STEPHEN R. SEILER joined Hybridon in 2001 as the company’s Chief
Executive Officer. Prior to joining Hybridon, Mr. Seiler was Executive
Vice President, Planning Investment & Development for Elan Corporation
Plc from 1995 to 2001. While at Elan, Mr. Seiler took part in and
oversaw activities in a wide range of areas including acquisitions,
divestitures and in/out licensing. From 1991 to 1995 Mr. Seiler worked
as an Investment Banker for Paribas Capital Markets in both London and
New York. He was founder of Paribas’ pharmaceutical industry investment
banking group. In that capacity, he initiated and worked on a wide
variety of transactions including IPOs, privatizations, M&A, debt and
equity offerings and derivative transactions. Mr. Seiler received a BA
summa cum laude in History from the University of Notre Dame in 1977 and
a JD (Honors) from Georgetown University in 1980. He is a member of the
bar in New York, Arizona and Missouri.