Cambridge, MA, January 2, 2002 - Expanding the company's clinical research internationally, the Ludwig Institute for Cancer Research has initiated the first European Phase I trial for Therion Biologics' two-component vaccine targeting the tumor antigen NY-ESO-1. In this study, the Ludwig Institute will evaluate the safety and potential activity of Therion's pox virus-based vaccine for enhancing the body's own immune response against cancer. This initial clinical study will include patients with a wide variety of ESO-expressing tumors, including breast and bladder cancer, melanoma and some sarcoma patients.

"The Ludwig Institute's efforts are dedicated to turning leading-edge science into novel treatments for a variety of cancers," said Lloyd J. Old, Chief Executive Officer at the Ludwig Institute for Cancer Research. "As the first product from our joint research efforts with Therion enters the clinic, we recognize and look forward to other milestones in this collaboration."

"This exciting transnational collaboration allows us to rapidly evaluate the potential benefits of NY-ESO-1 immunotherapy in cancer patients," said Dennis Panicali, Ph.D., President and Chief Executive Officer of Therion Biologics Corporation. "To date, Therion's 'prime-boost' approach to developing cancer vaccines has shown exciting and promising results in clinical trials for both prostate and colorectal cancer. Working with scientists from the Ludwig Institute in this trial offers an opportunity to further demonstrate the broad utility of our vaccine products for the treatment of cancer."

NY-ESO-1 Study Design
The Phase I dose-ranging trial will assess the safety and immunologic profile of recombinant vaccinia-NY-ESO-1 (rV-NY-ESO-1) and recombinant fowlpox-NY-ESO-1 (rF-NY-ESO-1) in approximately 60 patients with NY-ESO-1 expressing tumors and undetectable NY-ESO-1 specific serum antibodies. The study is designed to evaluate the utility of the "prime-boost" approach to cancer therapeutics, which works by priming the immune system with one species of poxvirus and boosting with another to increase immune response over time. In addition, researchers will monitor changes in NY-ESO-1 antigen-specific cellular and humoral immunity induced by the two vaccines, and look for correlation in the clinically observed changes in the tumors. The Ludwig Institute expects to complete the trial in mid 2003.

NY-ESO-1
NY-ESO-1 is found on several types of tumors including melanoma, breast and bladder cancer, as well as on some sarcomas. NY-ESO-1 is a member of a growing family of cancer antigens, referred to as cancer-testis (CT) antigens because their expression in normal tissue is restricted to testes. Other members of the CT family of antigens are MAGE, SSX, and SCP-1. CT antigens represent attractive targets identified to date for cancer vaccine development because of their specificity and their expression by a broad range of tumor types.

Therion Biologics
Therion Biologics Corporation is focused on the development of therapeutic vaccines for cancer and preventive vaccines for AIDS. Therion's most advanced product, PROSTVAC-VF, is currently in Phase II studies for prostate cancer. Under the terms of a strategic collaboration with Aventis Pasteur, a second product, ALVAC-CEA/B7.1, will move into pivotal clinical trials in the next two years for colorectal cancer. The company also has a broad pipeline of vaccines in early clinical development for treatment of major cancers, including breast cancer, melanoma and other solid tumors. In addition to Aventis, Therion's partners include the National Cancer Institute and a network of leading clinical institutions around the world. Therion is headquartered in Cambridge, Massachusetts.

The Ludwig Institute for Cancer Research
The Ludwig Institute for Cancer Research is an international not-for-profit organization that originates and conducts long-range research programs directed to the ultimate goal of eradicating cancer. Over 750 scientists, clinicians, and support staff in 14 countries focus on multiple aspects of basic and clinical cancer research, including cancer genetics and genomics, tumor immunology, and cell growth and differentiation.