Immunomedics, Inc. Reports Preclinical Results On New Therapeutic

MORRIS PLAINS, N.J., Dec. 15 /PRNewswire-FirstCall/ -- Immunomedics, Inc. today announced that the results of preclinical studies of its new antibody fusion protein, CD74-RNase immunotoxin, appeared in today’s issue of Blood, the official journal of the American Society of Hematology (ASH), and were also presented orally at the annual meeting of ASH on December 12, 2005, by Company Chairman, Dr. David M. Goldenberg.

This is the first recombinant immunotoxin comprising a humanized antibody against CD74 and an engineered ribonuclease (RNase). CD74 is a molecule present on certain blood cells involved in immune responses, as well as on lymphomas, myelomas, and some solid tumors. The recombinant immunotoxin is manufactured using the mammalian cell culture platform used to produce the Company’s other therapeutic humanized antibodies.

“Cell culture and animal studies indicated that this new immunotoxin killed CD74-positive human lymphoma and myeloma cells by interfering with RNA and protein synthesis. It was therapeutic in mice bearing human lymphomas, where a single dose as low as 1 microgram per mouse was effective, but a higher dose of 5-15 micrograms had even greater curative effects when given as a single dose in early or late stage disease,” commented Dr. Goldenberg. “Some toxicity was encountered at doses of 50 micrograms and higher, but this was 10-50-times the dose needed for cure,” he added. “Thus, we are encouraged with the therapeutic index of this new molecule,” Dr. Goldenberg stated.

Cynthia L. Sullivan, President and Chief Executive Officer, remarked: “Our humanized anti-CD74 antibody has shown therapeutic activity in lymphoma and myeloma transplants as a naked (unconjugated) antibody, conjugated with doxorubicin, and now as a fusion protein with RNase, thus providing us with several product candidates for further evaluation.”

The reference for the article is: Chang et al., Effective therapy of human lymphoma xenografts with a novel recombinant ribonuclease/anti-CD74 humanized IgG4 antibody immunotoxin. Blood 2005; 106:4308-14.

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. Our lead product candidate, epratuzumab, is currently in two pivotal Phase III trials for the treatment of patients with moderate and severe lupus (ALLEVIATE A and B). 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 believe that our portfolio of intellectual property, which includes approximately 90 patents issued in the United States, and more than 250 other issued patents worldwide, protects our product candidates and technologies. Visit our web site at http://www.immunomedics.com.

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, 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), 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

Immunomedics, Inc.

CONTACT: Dr. Chau Cheng, Associate Director, Investor Relations & BusinessAnalysis of Immunomedics, Inc., +1-973-605-8200, ext. 123,ccheng@immunomedics.com

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