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Immunomedics Announces Preclinical Results of TF2 for Pretargeted Imaging of Colon Cancer

/ Source: GlobeNewswire

ORLANDO, Fla., April 6, 2011 (GLOBE NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company primarily focused on the development of monoclonal antibody-based products for the targeted treatment of cancer, autoimmune and other serious diseases, today reported results that indicate immunoPET with TF2 and a gallium-68 (68Ga)-labeled peptide is a highly specific and sensitive imaging method for colon cancer. Results from this pretargeted study were presented at the 102nd annual meeting of the American Association for Cancer Research.

TF2 is a new generation of bispecific antibodies constructed using the Company's patented Dock-and-Lock (DNL) protein engineering platform technology. It specifically targets the carcinoembryonic antigen (CEA or CEACAM5) expressed in many human cancers, including colorectal cancer. Unlike conventional antibodies which can only attach to one receptor, TF2 has been modified to contain an additional binding site that recognizes a radioisotope-carrying peptide.

The creation of an additional binding site in bispecific antibodies, such as TF2, is designed to be used in pretargeting methods. Developed by the Company's majority-owned subsidiary, IBC Pharmaceuticals, Inc., pretargeting separates the delivery of radiation from the infusion of the tumor-targeting bispecific antibody. Only after the bispecific antibody has selectively localized to the target tumor and unbounded antibody has been removed from the rest of the body is the small radioisotope-carrying peptide injected. The advantage of this approach is to improve the signal at the tumor relative to the background, or selectively increase the amount of therapeutic in the tumor.

The objective of this preclinical study was to determine the feasibility and specificity of pretargeted immunoPET detection of colon cancer with TF2 and a small peptide labeled with 68Ga. Mice with a subcutaneous CEA-positive tumor on the right hind leg and an inflammation in the left thigh muscle were used. Pretargeted immunoPET was also tested in mice with intraperitoneal or abdominal CEA-expressing tumors.

Within one hour of injecting the 68Ga-labeled peptide, pretargeted immunoPET scan revealed a rapid and very specific uptake of radioactivity in the tumor, while the inflamed muscle was not visualized. As a result, high tumor to background ratios of radioactivity concentrations (e.g. tumor/intestines ratio of 57.5 +/- 22.4) were obtained. In contrast, 18F-FDG, the most widely used radiopharmaceutical approved for use in the U.S. for the detection of certain tumors, localized efficiently in the tumors (8.7 +/- 3.1 % ID/g), as well as in the inflamed muscle and in a number of normal tissues, resulted in a tumor to intestines ratio of 4.0 +/- 0.9, a more than 10-fold decrease compared with TF2. 

Efficient tumor uptake of the 68Ga-labeled peptide in the intraperitoneal CEA-positive tumors (23.4 +/- 7.2% ID/g) was also observed. The high and specific uptake in the CEA-expressing tumors combined with the very low uptake in normal tissues, such as the intestines, produced clear visualization of very small abdominal tumors of less than 2mm. 

"We believe these results demonstrated that pretargeted immunoPET performs exceptionally well with short-lived radionuclides, and is a highly sensitive procedure for detection of small tumor deposits that is also more specific than FDG-PET," commented Cynthia L. Sullivan, President and CEO of Immunomedics.

First clinical experience with TF2 for pretargeted imaging in patients with advanced colorectal cancer was recently reported. (For more information, please refer to the Company's press release at ).

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, cytokines 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 172 patents issued in the United States and more than 400 foreign patents, protects our product candidates and technologies. For additional information on us, please visit our website at . 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.

CONTACT: Dr. Chau Cheng Director, Investor Relations & Grant Management (973) 605-8200, extension 123