Immunomedics Announces Preclinical Therapy Results of SN-38 Immunoconjugate for Colorectal Cancer

SAN FRANCISCO, Jan. 20 /PRNewswire-FirstCall/ – Immunomedics, Inc. (Nasdaq: IMMU), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today announced that results presented at the 2009 Gastrointestinal Cancers Symposium showed that labetuzumab-SN-38, an antibody-drug conjugate, selectively delivers SN-38 to human colon carcinoma in animal models as an effective new therapy.

SN-38 is the active metabolite of irinotecan, a chemotherapeutic agent approved by the FDA for the treatment of colorectal, lung, and other cancers. Due to its toxicity and poor solubility, SN-38 cannot be administered systemically to cancer patients. The Company has previously reported that by conjugating SN-38 to antibodies, the powerful cancer drug can be delivered selectively to tumors, thereby increasing the amount reaching the tumors and minimizing damage to normal tissues and organs. (Please refer to http://www.immunomedics.com/news_pdf/2008_PDF/PR03202008.pdf).

In this study, the therapeutic efficacy of SN-38 conjugated to labetuzumab was evaluated in two animal models of human colon cancer. Labetuzumab is a non-internalizing humanized antibody that binds to the carcinoembryonic antigen (CEACAM5) expressed by many solid cancers. The Company has conducted clinical trials with the naked and radiolabeled antibody in patients with colorectal, breast and pancreas cancers.

In a lung metastatic model of colon carcinoma, therapy with labetuzumab-SN-38 conjugate increased median survival time (MST) 1.9- to 3.4-fold compared to various controls, with 20% of animals alive at the end of the study. In another colon cancer model, MST for the immunoconjugate treatment group increased 4-fold to 86 days compared to untreated animals, and was significantly better than all controls, including irinotecan administered at its maximum tolerated dose, which is a 50-fold increase in the amount of free drug than SN-38 in the immunoconjugate dose.

“We believe these results suggest that targeted chemotherapy of colorectal cancer with labetuzumab-SN-38 should enhance the bioavailability and reduce the toxicity of the clinically validated drug, irinotecan,” commented Cynthia L. Sullivan, President and CEO. “More preclinical evidences are being collected to support the human testing of this new drug immunoconjugate,” she added.

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 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.

    For More Information:
    Dr. Chau Cheng
    Associate Director, Investor Relations & Business Analysis
    (973) 605-8200, extension 123
    ccheng@immunomedics.com

SOURCE Immunomedics, Inc.