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Immunomedics Reports Advances With New Imaging Agent Developments for Positron Emission Tomography

/ Source: GlobeNewswire

SAN ANTONIO, June 8, 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 announced that 4 studies, using the Company's recently patented peptide labeling method with the radioisotope fluorine-18 (18F), for improved positron emission tomography (PET) imaging of diseases, were presented at the 2011 Annual Meeting of the Society of Nuclear Medicine.

The new labeling method involves the formation of an aluminum-18F complex (Al18F), which is then bound to a NOTA ligand, attached to a peptide and is applicable to essentially any peptide that is stable at 100oC. (For more information on the labeling method, please refer to the Company's press release at ).

Two of the studies focused on improving the method by changing the ligand. The first study created a new ligand called NODA-MPAA, which can be securely linked to peptides. High-yield 18F-labeling of a NODA-MPAA-linked peptide was achieved in the next step using commercial 18F in saline solution. 

The Al18F-labeled peptide was stable in human serum at 37oC for at least 4 hours. In vivo, it cleared rapidly via the kidneys with minimal accumulation in the bone or other tissues. Moreover, in a bispecific antibody pretargeting setting, tumor uptake of the peptide was rapid, producing a tumor-to-blood ratio of 100 within 1 hour. Two other peptides, a somatostatin receptor-binding peptide and a gastrin-releasing peptide (GRP), linked to NODA-MPAA were also radiofluorinated in high yield.

In the second study, the new NODA-MPAA ligand was modified for the 18F-labeling of temperature-sensitive and insensitive peptides or proteins, including antibodies. This was carried out by first labeling the modified NODA-MPAA with Al18F before the Al18F-labeled ligand was coupled to a protein or peptide at room temperature. Total radiolabeling time was less than 50 minutes and the attachment of 18F to protein was stable in vitro and in vivo with low uptake in the bone.

The goal of the third study, which was presented earlier at the meeting, was to evaluate the targeting of tumors expressing the GRP receptor with 18F-labeled-bombesin. GRP receptors are highly expressed by various tumors that include prostate, breast and ovarian. Bombesin analogs are promising ligands for imaging these tumor cells. Biodistribution studies in mice carrying human prostate tumor cells showed specific accumulation of 18F-labeled-bombesin in the tumors.

The fourth presentation reported the development of a rapid one-step, lyophilized kit to radiolabel peptides with 18F at high specific activity. Labeling is performed in aqueous solution with no dry down step required. The peptide kits can be radiolabeled by adding commercially available 18F in saline, heating briefly and then rapidly purified with an inexpensive disposable cartridge. The entire process takes approximately 30 minutes and may be reduced to 20 minutes with automation. Several different peptides have been formulated and labeled with comparable radiolabeling results. The radiolabeled peptides are stable in vitro and in vivo. More importantly, the kit is labeled with USP 18F in saline and can be validated.

"These results have clearly demonstrated the significant progress we have made with this important new labeling technology, which we believe has the potential of developing into diverse PET imaging kits for multiple disease imaging applications," remarked Cynthia L. Sullivan, President and Chief Executive Officer.

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 178 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