MORRIS PLAINS, N.J., Dec. 31, 2013 (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 the issuance of U.S. patent no. 8,617,558 for additional claims under the patent family "Camptothecin-binding moiety conjugates," and U.S. patent no. 8,617,518 with additional claims for the patent family "Methods and compositions for improved F-18 labeling of proteins, peptides and other molecules." Patent 8,617,558 relates to our proprietary linker technology for conjugating SN-38 to the Company's humanized antibodies for targeted delivery of the potent drug to the tumor. The patent will expire in December 2023. Additional patents covering the Company's antibody-drug conjugates are being prosecuted in major countries worldwide. "This is a key patent for the protection of our antibody-drug conjugates patent family, of which IMMU-132, an anti-TROP-2-SN-38 conjugate, and IMMU-130, an anti-CEACAM5-SN-38 conjugate, constitute two of our most exciting new agents for solid cancer therapy," commented Cynthia L. Sullivan, President and Chief Executive Officer. "Both IMMU-132 and 130 are in Phase II clinical development and we plan to report results from these studies in the second quarter of 2014 at upcoming scientific and medical conferences." In early dose-escalation studies, the two antibody-SN-38 conjugates have shown evidence of tumor shrinkage in patients with difficult-to-treat solid tumors who had failed multiple prior therapies, including irinotecan. SN-38 is the active metabolite of irinotecan, a camptothecin analogue approved for the treatment of metastatic colorectal cancer. While SN-38 is 2 to 3 orders of magnitude more potent than its parent molecule, it does not dissolve in water and cannot be administered directly to patients. Our unique linker allows us to produce antibody-SN-38 conjugates that are soluble in water with excellent yields, as well as preservation of antibody binding and drug activity, even after attaching about 7 drug molecules per antibody.