Immunomedics Researchers Report on New Cancer Therapy

Scientists from Immunomedics, Inc. (Morris Plains, NJ), in collaboration with researchers at the Garden State Cancer Center (Belleville, NJ) and Immunotech SA (Marseille, France), reported their progress in the development of a new cancer therapy at the 90th annual meeting of the American Association for Cancer Research in Philadelphia.

The research group described a two-step method whereby a cancer is targeted with an unlabeled, bispecific antibody, and the therapeutic radioisotope is given later attached to a carrier that is recognized by the bispecific antibody. Until now, such bispecific antibodies were of mouse origin, but the Immunomedics team has now constructed the bispecific antibody as a human/mouse hybrid as a prelude to a fully humanized antibody. A fully humanized bispecific antibody is preferred for repeated therapy injections, since it is less immunogenic to patients than a mouse antibody. In the experiments reported, the humanized antibody against carcinoembryonic antigen, hMN-14, which comprises the Immunomedics' CEA-Cide product in clinical trials, was used as half of the bispecific antibody.

In pre-clinical experiments involving transplants of human colonic cancer, the 2-step pretargeting method showed a higher tumor uptake of the radioisotope at a markedly higher ratio compared to normal tissues than when a single-step, radiolabeled monospecific antibody is given.

According to Hans J. Hansen, one of the authors of this paper and VP of R&D at Immunomedics: "We showed that an imaging and therapeutic isotope combination, Tc-99m and Re-188, could function in this new system for detecting and treating cancers, but at much higher doses delivered more specifically to the cancers than we and others have experienced with prior methods involving radiolabeled monospecific antibodies."

"This new targeting and therapy system is being prepared for clinical trials by Immunomedics' joint venture with Beckman Coulter Corp., IBC Pharmaceuticals, LLC, which licensed the applicable patents from Immunotech SA, and which is now setting up operations in New Jersey and Marseilles, France," Dr. Hansen added. "This basic two-step, pretargeting method has been applied successfully in France in the imaging and therapy of about 300 cancer patients, thus awaiting the availability of our new, humanized, bispecific antibodies for clinical trials."

Immunomedics is a biopharmaceutical company focused on the development, manufacture, and commercialization of diagnostic imaging and therapeutic products for the detection and treatment of cancer and infectious diseases.

For more information: Cynthia Sullivan, Executive VP, Immunomedics Inc., 300 American Rd., Morris Plains, NJ 07950. Tel: 973-605-8200, Ext. 109. Fax: 973-605-8282. Email: immuno@immunomedics.com.