Immunomedics Reports Veltuzumab Enhances Radioimmunotherapy With Epratuzumab in Lymphoma Model

Preclinical Results Presented At 2008 Annual Meeting of the American Association for Cancer Research (AACR)

SAN DIEGO, April 14, 2008 (PRIME NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today reported that combining veltuzumab, the Company's proprietary humanized anti-CD20 antibody, with yttrium-90-labeled epratuzumab, its humanized anti-CD22 antibody, improves treatment responses in a human lymphoma model. The preclinical results were presented at the 2008 Annual Meeting of American Association for Cancer Research in San Diego, California.

Nude mice bearing established human B-cell lymphoma transplants received yttrium-90-epratuzumab alone, yttrium-90-epratuzumab in combination with veltuzumab, or yttrium-90-veltuzumab in combination with epratuzumab. All animals tolerated the combination therapies as well as the yttrium-90-epratuzumab, indicating that the addition of unlabeled antibody did not increase toxicity.

Yttrium-90-labeled epratuzumab had a strong therapeutic effect by itself; all of the tumors regressed within 2 weeks of treatment with many becoming undetectable. However, the majority of the tumors grew back a few weeks later, and then proceeded to grow rapidly.

The addition of veltuzumab to yttrium-90-labeled epratuzumab prevented the re-growth of the tumors and produced apparent cures in the majority of the mice. Approximately 85% of tumors in animals given the combination regressed completely with no evidence of re-growth over a period of 5 months.

The addition of epratuzumab to yttrium-90-labeled veltuzumab demonstrated tumor regression over a period of 1-2 weeks; however, tumors grew back rapidly, suggesting the addition of epratuzumab was not as potent as veltuzumab in this protocol and tumor model.

"We are in the process of formulating a strategy for bringing the appropriate combination therapy of Y-90-labeled epratuzumab and unlabeled veltuzumab into clinical trials based on prior clinical results with each agent alone," commented Cynthia L. Sullivan, President and Chief Executive Officer.

Current radioimmunotherapy for non-Hodgkin's lymphoma using anti-CD20 antibodies labeled with radioisotopes have been successfully producing higher objective response rate than their unconjugated counterparts. The radioimmunotherapy regimen, however, involves a large dose of approximately 400 mg of the naked antibody. The objective of this study was to examine if yttrium-90-labeled epratuzumab (anti-CD22 antibody) in combination with veltuzumab (anti-CD20 antibody) would result in better therapeutic effects, which was in fact confirmed in these studies.

About Immunomedics

Immunomedics is a New Jersey-based biopharmaceutical company 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 have exclusively licensed our lead product candidate, epratuzumab, to UCB for the treatment of all autoimmune disease indications worldwide. Epratuzumab's most advanced clinical testing is for the treatment of systemic lupus erythematosus (SLE) and in non-Hodgkin's lymphoma (NHL). At present, there is no cure for lupus and no new lupus drug has been approved in the U.S. in the last 40 years. We have retained the rights for epratuzumab in oncology indications, and are advancing trials in lymphoma and in childhood acute lymphoblastic leukemia in cooperation with National Cancer Institute Study Groups. In addition, the Company is conducting clinical trials with intravenous veltuzumab in patients with NHL and immune thrombocytopenic purpura, subcutaneous veltuzumab in NHL and chromic lymphocytic leukemia (CLL), 90Y-epratuzumab for the therapy of patients with lymphoma, 90Y-hPAM4 combined with gemcitabine for pancreatic cancer therapy, and milatuzumab (anti-CD74 humanized antibody) as a therapy for patients with multiple myeloma, NHL, and CLL. 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. The Company is working to advance this new technology into clinical testing. We believe that our portfolio of intellectual property, which includes approximately 116 patents issued in the United States and more than 290 other patents issued worldwide, protects our product candidates and technologies. For additional information on us, please visit our website at http://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, patent protection, 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 partner for the further development of epratuzumab for autoimmune 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.

-0- CONTACT: Immunomedics, Inc. Dr. Chau Cheng, Associate Director, Investor Relations & Business Analysis (973) 605-8200, extension 123 ccheng@immunomedics.com

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Posted: April 2008

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