Toronto, Ontario and Cambridge, MA, January 14, 1998 - Pasteur M�rieux Connaught, world leader in vaccines, and Therion Biologics Corporation, a leading biotechnology firm, are joining forces to develop vaccines to treat certain cancers.

The firms, Pasteur M�rieux Connaught (Rhone-Poulenc Group), the world's largest vaccine manufacturer, and Therion Biologics Corporation, a leader in the development of therapeutic vaccines for cancer and preventive vaccines for AIDS, are working on a new way of treating cancers through vaccines.

The agreement represents one of the first announcements by Pasteur M�rieux Connaught under its Canadian-led, new cancer vaccine initiative and Therion's first major commercial alliance.

Pasteur M�rieux Connaught's cancer initiative, launched last year, aims in the long run to defeat the leading health problem in the world today - cancer - according to Mark Lievonen, Senior Vice President and General Manager, Oncology Business Unit.

"As the term vaccine implies, we propose to enlist the immune system in the battle against cancer," says Lievonen. "We are fortunate to forge this alliance with such a respected and innovative partner as Therion Biologics."

Specifics of the Agreement

The firms have formed a strategic alliance to develop and commercialize therapeutic vaccines for the treatment of colorectal and lung cancers and melanoma, the companies announced today. In conjunction with the collaboration, the companies entered into a cross-licensing agreement that provides Pasteur M�rieux Connaught with exclusive rights to certain therapeutic cancer vaccines being developed by Therion, and provides Therion with access to certain pox virus vector technologies controlled by Pasteur M�rieux Connaught and its affiliate, Virogenetics Corporation, for the development and commercialization of cancer products. Therion currently has four therapeutic vaccines for melanoma, one vaccine for colorectal and lung cancer, and one vaccine for prostate cancer in Phase I/II clinical trials in the United States.

Under the terms of the agreement, Pasteur M�rieux Connaught will receive exclusive worldwide rights to commercialize, develop and manufacture Therion's therapeutic melanoma vaccines and carcinoembryonic antigen (CEA)-based therapeutic vaccines. In return for commercial rights to these products and for the acquisition of related intellectual property, Therion will receive up to $25 million in payments from Pasteur M�rieux Connaught subject to achievement of all scientific, clinical and regulatory milestones. Therion also gains access to certain pox virus vector patents controlled by Pasteur M�rieux Connaught for Therion's cancer products. As a part of the agreement, Pasteur M�rieux Connaught is making an initial equity investment in Therion.

"Therion Biologics has built a leadership position in cancer immunotherapy based on its recombinant pox virus vector technologies and has rapidly moved its CEA-based and melanoma products through preclinical and early clinical development in collaboration with the National Cancer Institute. These products will form an important component of our cancer vaccine research program and will complement the other research and development activities that we are undertaking as part of our cancer vaccine program," explained Lievonen.

"Our alliance with Pasteur M�rieux Connaught, a world leader in vaccines, is a major endorsement of our cancer immunotherapy strategy and will accelerate key product development programs, building on the progress we have made to date," said Dennis L. Panicali, Ph.D., Therion's President and Chief Executive Officer. "In addition, our combined patent portfolios in pox virus vectors help ensure that we can pursue all of our therapeutic programs and focus on issues of development and commercialization." Dr. Panicali noted that Therion is also developing products for the treatment of other major cancers, including breast, prostate and ovarian cancers, and for the prevention of AIDS.

The Science of the Agreement

The therapeutic vaccines covered by this agreement are live recombinant pox virus vectors engineered to elicit specific immune responses for cancer immunotherapy and were developed by Therion as a part of two Cooperative Research and Development

Agreements (CRADAs) with leading researchers at the National Cancer Institute. These vaccines have shown promise in early clinical studies. Phase I trials have demonstrated that vaccination with TBC-CEA, Therion's lead colorectal and lung cancer product, elicits a greatly enhanced and specific cellular immune response to CEA, a tumor-associated antigen expressed in the majority of colorectal and lung cancers. The company's therapeutic vaccines for melanoma are designed to induce similar potent immune responses against MART-1 and gp100, antigens that are present on nearly all melanomas. In addition, Therion's cancer products have exhibited strong safety profiles in the more than 200 patients vaccinated to date.

Therion Biologics Corporation is engaged in the development of therapeutic vaccines for cancer and preventive vaccines for AIDS. Therion is headquartered in Cambridge, Massachusetts.

Pasteur M�rieux Connaught (Rhone-Poulenc Group) is the world leader in vaccines, with more than one billion doses sold each year. Rhone-Poulenc is one of the world's leading life sciences and specialty chemical companies. Through its innovative products, Rhone-Poulenc contributes to the improvement of human, animal and plant health and to the quality and safety of products used in daily life.

Pasteur M�rieux Connaught is the new trade name of Pasteur M�rieux Serums & Vaccines S.A. (based in Lyon, France) and all its subsidiaries worldwide, including Connaught Laboratories, which operates in North America.