WASHINGTON, April 19, 2010 (GLOBE NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, reported today at the 101st Annual Meeting of the American Association for Cancer Research (AACR) results from two studies aimed at improving the design of antibody-SN-38 conjugates for targeted cancer chemotherapy.
SN-38 is an active form of, and about three orders of magnitude more potent than, irinotecan or CPT-11, which has been approved for the treatment of metastatic colorectal cancer. CPT-11 has also shown clinical activity in lung, breast, and brain cancers. Due to its toxicity and poor solubility in water, SN-38 cannot be administered systemically to patients with cancer. Targeting drugs such as SN-38 to cancer cells using cancer-selective monoclonal antibodies could lower their toxicities to bystander tissues, thus potentially offering an attractive alternative as cancer therapeutic agents.
The first study reported at the AACR conference evaluated 4 linkers to connect SN-38 to labetuzumab or hRS7, two of the Company's proprietary humanized monoclonal antibodies. Stabilities of the antibody-SN-38 conjugates were examined in human or mouse serum. In vitro binding and cytotoxicities of the ADCs were studied using human colon cancer cells, and comparison of the therapeutic potentials of the conjugates was carried out in a human colon cancer model in mice. Overall, results indicated that a redesigned linker labeled as CL2A provides a practical approach for antibody-based targeted chemotherapy with SN-38.
Efficacies of antibody-SN-38 conjugates redesigned with CL2A were investigated in the second study. Five of the Company's humanized antibodies were conjugated to CL2A-SN-38: epratuzumab (anti-CD22), veltuzumab (anti-CD20), clivatuzumab (anti-mucin), labetuzumab (anti-CEACAM5) and hRS7 (anti-EGP-1, or TROP-2). In a mouse model of human pancreatic cancer, SN-38 conjugates of labetuzumab and hRS7 produced enhanced antitumor effects versus veltuzumab-SN-38 conjugate, which does not target pancreatic cancer, suggesting the binding abilities of labetuzumab and hRS7 were retained in both conjugates. Additionally, in a subcutaneous lymphoma model in mice, median survival time (MST) for untreated animals was only 7 days, while the tumor-specific epratuzumab-SN-38 conjugate in combination with veltuzumab increased MST 10-fold to more than 77 days.
Commenting, Cynthia L. Sullivan, President and CEO stated, "The redesigned CL2A linker developed by our scientists allows us to produce SN-38 conjugates that are soluble in water with excellent yields, as well as preservation of antibody binding and drug activity. These results portend well for the clinical development of these redesigned antibody-SN-38 conjugates for different cancer indications."
These studies were supported in part by Award Number R44CA114802-02 from the National Cancer Institute. The contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health.
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 148 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.