Cytogen Corporation announced that it will regain rights to ex vivo prostate cancer immunotherapy using prostate specific membrane antigen (PSMA), in connection with the termination of its agreement with Northwest Biotherapeutics Inc, effective January 17, 2003.

Cytogen entered into an agreement with Northwest Biotherapeutics in August 2000 that gave Northwest Biotherapeutics a license to develop and commercialize ex vivo immunotherapy products for prostate cancer that are produced by pulsing isolated populations of a patient's antigen presenting cells (such as dendritic cells) with PSMA. Northwest Biotherapeutics, which terminated the program for funding purposes in November 2002, advanced this program to the initiation of Phase III clinical trials.

"We are very encouraged by efforts to date demonstrating a favorable safety and clinical response in prostate cancer patients treated using PSMA- based ex vivo immunotherapy," said Michael D. Becker, Cytogen's president and chief executive officer. "Based on this information, we will seek other corporate collaborations or partnerships to help us realize the clinical and commercial potential of this approach."

The PSMA gene was first discovered by scientists at Memorial Sloan- Kettering Cancer Center in New York City and is exclusively licensed to Cytogen Corporation, which has sublicensed it to the PSMA Development Company for in vivo immunotherapy. PSMA is a cell-surface protein abundantly expressed on prostate cancer cells and therefore is an attractive target for vaccine and antibody-based cancer immunotherapies. Further work demonstrated that PSMA is also present at high levels within newly formed blood vessels (neovasculature) needed for the growth and survival of solid tumors. These observations suggest that PSMA-targeted approaches may be valuable in treating a broad range of cancers.