TORONTO, June 17, 2009 (GLOBE NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today announced that naked veltuzumab enhances the therapeutic response to a veltuzumab-based pretargeted radioimmunotherapy (PT-RAIT) in a human non-Hodgkin's lymphoma model.
RAIT utilizes an antibody to deliver targeted radiation to tumors. One of the challenges of conventional RAIT is that antibodies that are not attached to their targets stay in the body for a significant period of time, exposing the body and the bone marrow, in particular, to the harmful effects of radiation unnecessarily, and limiting the level of the tolerated radioisotope dose.
Developed by scientists at IBC Pharmaceuticals, Inc., the Company's majority-owned subsidiary, PT-RAIT overcomes the problem by separating the delivery of radioisotope from the administration of the antibody. This allows unbound antibodies to be cleared from the body before the therapeutic isotope is administered. The latter agent either targets the antibody localized at the tumor, or is rapidly excreted in the urine, thereby minimizing the body's radiation exposure. The main therapeutic advantage of PT-RAIT is a higher delivery of radiation to the tumors without increased toxicity to normal tissues.
The Company has previously reported that PT-RAIT, when compared to conventional RAIT, improved anti-tumor responses with less toxicity in a lymphoma model. (Please refer to the Company's press release at www.immunomedics.com/news_pdf/2008_PDF/PR04142008.pdf for more information). The goal of this study was to evaluate if adding a naked antibody to PT-RAIT could improve efficacy.
TF4, an anti-CD20 antibody constructed using the Company's patented protein engineering platform technology called Dock-and-Lock (DNL), was used as the PT-RAIT agent in this study. In mice bearing human lymphoma cells, TF4 alone improved survival by only 1 week compared to untreated animals. Adding veltuzumab, the Company's next-generation humanized anti-CD20 antibody, to TF4 considerably improved survival by 5 weeks. However, pre-dosing of naked veltuzumab should be minimized because 1 mg (4 mg/kg human equivalent) of veltuzumab, when added before TF4, was found to significantly reduce the therapeutic efficacy of the combination therapy. Giving veltuzumab after PT-RAIT, however, was most effective.
About Pretargeted Radioimmunotherapy
Pretargeted radioimmunotherapy (PT-RAIT) uses a 'two-step' approach in the delivery of therapeutic isotope. A humanized bispecific monoclonal antibody (bsMAb), with one arm that recognizes a tumor-associated antigen and another arm that recognizes a peptide that carries a therapy agent, is given as a first injection. When non-tumor-bound bsMAb has substantially cleared non-target tissues and bsMAb has reached a maximum level in the tumor, the bsMAb-recognizable therapy agent is given. The latter agent either targets the bsMAb localized at the tumor, or it is rapidly cleared through urine via the kidneys. PT-RAIT is an attractive potential alternative to traditional RAIT, because the delivery of therapeutic isotope is rapid and is separated from the long antibody delivery process, thereby reducing the harmful effects of radiation to the body, especially the bone marrow.
About Immunomedics
Immunomedics is a New Jersey-based biopharmaceutical company primarily focused on the development of monoclonal, antibody-based products for the targeted treatment of cancer, autoimmune and other serious diseases. We have developed a number of advanced proprietary technologies that allow us to create humanized antibodies that can be used either alone in unlabeled or "naked" form, or conjugated with radioactive isotopes, chemotherapeutics or toxins, in each case to create highly targeted agents. Using these technologies, we have built a pipeline of therapeutic product candidates that utilize several different mechanisms of action. We also have a majority ownership in IBC Pharmaceuticals, Inc., which is developing a novel Dock-and-Lock (DNL) methodology with us for making fusion proteins and multifunctional antibodies, and a new method of delivering imaging and therapeutic agents selectively to disease, especially different solid cancers (colorectal, lung, pancreas, etc.), by proprietary, antibody-based, pretargeting methods. We believe that our portfolio of intellectual property, which includes approximately 134 patents issued in the United States and more than 300 other patents issued worldwide, protects our product candidates and technologies. For additional information on us, please visit our website at www.immunomedics.com. The information on our website does not, however, form a part of this press release.
This release, in addition to historical information, may contain forward-looking statements made pursuant to the Private Securities Litigation Reform Act of 1995. Such statements, including statements regarding clinical trials, out-licensing arrangements (including the timing and amount of contingent payments), forecasts of future operating results, and capital raising activities, involve significant risks and uncertainties and actual results could differ materially from those expressed or implied herein. Factors that could cause such differences include, but are not limited to, risks associated with new product development (including clinical trials outcome and regulatory requirements/actions), our dependence on our licensing partners for the further development of epratuzumab for autoimmune indications and veltuzumab for non-cancer indications, competitive risks to marketed products and availability of required financing and other sources of funds on acceptable terms, if at all, as well as the risks discussed in the Company's filings with the Securities and Exchange Commission. The Company is not under any obligation, and the Company expressly disclaims any obligation, to update or alter any forward-looking statements, whether as a result of new information, future events or otherwise.