CAMBRIDGE, MA, June 30, 2003 - Therion Biologics Corporation, a leading developer of therapeutic cancer vaccines, today announced the appointment of Thomas J. Schuetz, M.D., Ph.D., to the position of Chief Medical Officer. A board certified oncologist, Dr. Schuetz brings to Therion a comprehensive understanding of clinical and regulatory processes. Prior to joining Therion, Dr. Schuetz served as Vice President, Clinical Affairs at Transkaryotic Therapeutics, Inc. (TKT), where he developed and supervised the clinical development strategy for Replagal, which led to marketing approval for the treatment of Fabry's disease in the European Union in 2001 and in other countries since then.

"Tom's experience will provide essential clinical development expertise and strategic vision for our commercial vaccine candidates," said Mark Leuchtenberger, Therion's President and Chief Executive Officer. "His demonstrated success in bringing a product to market will be instrumental as we design and implement late stage trials for our three lead candidates, PROSTVAC^�-VF, PANVAC-VF and VF-TRICOM�. Phase II trials for these products, for the treatment of prostate cancer, pancreatic cancer and melanoma, respectively, are anticipated to begin within the next 12 months."

"Therion's leadership in pox virus vector technology and its impressive clinical portfolio have brought the company to a pivotal stage in its evolution," commented Dr. Schuetz. "I am eager to work with this talented team towards the commercialization of Therion's promising immunotherapies for multiple challenging cancers."

While at TKT, Dr. Schuetz was integral in creating the company's clinical affairs department, where he supervised clinical development programs from Phase I through IV. He served as principal author of all clinically related regulatory submissions and served as TKT's clinical representative before worldwide regulatory authorities. In addition to his leadership on Replagal, Dr. Schuetz was critical in initiating clinical development programs for Dureplace for the treatment of Mucopolysaccahridosis Type II and Factor VIII Transkaryotic Gene Therapy for patients with haemophilia. He also provided consultation to Aventis Pharmaceuticals regarding several clinical development programs, which led to the marketing approval of Dynepo for the treatment of anemia in the European Union. Dr. Schuetz is a primary author of several published scientific papers and issued patents, including the patented treatment for alpha-galactosidase A deficiency. Dr. Schuetz received his M.D. cum laude and Ph.D. from Harvard University and his B.S. in chemistry summa cum laude from Xavier University.

About Therion Biologics Corporation
Therion Biologics Corporation develops therapeutic vaccines for cancer and preventive vaccines for AIDS. The Company has three lead programs involving multiple clinical trials: PROSTVAC^�-VF for prostate cancer; PANVAC-VF for pancreatic cancer; and VF-TRICOM for melanoma. Therion is also applying its technology platform to develop vaccines to treat breast cancer and other solid tumors. The Company's strategic partners include the National Cancer Institute, a global network of leading clinical institutions, and Aventis Pasteur, Ltd., which is developing ALVAC-CEA/B7.1, a clinical candidate for colon cancer. Therion is headquartered in Cambridge, Massachusetts.