Immunomedics Inc has reported data on the use of two novel therapeutic monoclonal antibodies at the 39th annual meeting of the American Society of Clinical Oncology in Chicago, Il. The humanized antibodies, which were developed internally by the Company's scientists, bind to the CD20 and CD74 receptors, respectively. CD20 is the target of the existing cancer therapeutic, rituximab (Rituxan, IDEC/Genentech), which is a successful chimeric monoclonal antibody currently used for the treatment of non-Hodgkin's lymphoma, and under investigation for the treatment of certain autoimmune diseases. The 2nd generation CD20 antibody developed by Immunomedics was reported as having reshaped genes coding for the antigen-binding regions of rituximab combined with the genes coding for the framework regions, or backbone, of epratuzumab, the Company's humanized CD22 monoclonal antibody.

"Our aim was to retain the functional activity of the tumor-binding regions of rituximab, together with the complement and effector-binding regions of epratuzumab, which has shown excellent safety and infusion properties in clinical trials to date," explained Dr. Ivan D. Horak, Executive Vice President of Research and Development at Immunomedics.

"These initial preclinical results further support our belief that our CD20 antibody's binding and anti-lymphoma activity are comparable in many respects to that of rituximab, both in vitro and in an animal xenografts of human Burkitt lymphoma," he added.

"Most importantly," Dr. Horak added, "the initial preclinical results strongly suggest that by combining our new CD20 antibody with our CD22 antibody, epratuzumab, currently in Phase II trials, we can significantly extend the survival of lymphoma-bearing animals when compared to the use of either agent alone, which would confirm the preliminary results of earlier clinical studies evaluating the combination of epratuzumab with rituximab."

Immunomedics also revealed promising therapeutic results with a CD74-binding humanized antibody during its update to oncologists and analysts at a special reception. This novel antibody was developed by the Company to be used as a drug immunoconjugate, because it can internalize rapidly into tumor cells expressing CD74, thus enhancing drug uptake. The results of trials involving both in vitro and in human lymphoma transplants in mice suggest that a single injection of the CD74 antibody conjugated with the anticancer drug, doxorubicin, could successfully treat almost all of the cancers. Even when the doxorubicin-CD74 antibody conjugate was given in a single dose to animals with very advanced disease, a significant number could still be cured by this treatment. Neither the administration of the drug alone, nor the drug conjugated to other antibodies at higher doses, could achieve comparable results, according to the data presented by Dr. Horak.