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-- Pretargeting System Allows Dual Nuclear/Fluorescence Imaging During Cancer Surgery --
-- Results Reported at SNMMI 2013 Annual Meeting --
VANCOUVER, British Columbia, June 10, 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 development of a pretargeting system that can detect and optically image a tumor during surgery. Results from this preclinical study were presented by Dr. Mark Rijpkema of the Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
While tumor detection with specific radiotracers may be a useful tool for accurate localization and resection during surgery, these procedures could benefit from the addition of an optical tracer, since this may allow for more accurate delineation of the tumor and resection margins. Both tracers in such a dual modality approach need to show high specificity and a high tumor-to-background ratio (TBR).
The pretargeting system that the Company is pursuing involves the bispecific antibody, TF2, which targets the carcinoembryonic antigen (CEA), specifically CEACAM5, expressed in many human cancers, including breast, colorectal and lung cancer, and which is also being used in its IMMU-130 antibody-drug conjugate in clinical trials. Created by the Company's proprietary DOCK-AND-LOCK™ method, the bispecific antibody is currently in a number of clinical trials for pretargeted immunoPET imaging and radioimmunotherapy of patients with CEA-expressing cancers.
The other component of the pretargeting system is a small peptide bearing both the fluorescent dye, IRdye800CW, and a linker called DOTA for radiolabeling. Designated as RDC-018, this new peptide was derived from an earlier peptide, IMP288, that has been used successfully in pretargeting with a number of radioisotopes such as indium-111 (
111In), yttrium-90, lutetium-177 and iodine-124.
The goal of this preclinical study was to assess the potential utility of this peptide for cancer detection by both optical (light) and radionuclide imaging, starting with an assessment of the radiolabeling procedure for RDC-018, and leading into in vivo biodistribution and tumor localization properties in a pretargeting setting compared to the
111In-IMP288. Animals bearing subcutaneous CEA-positive human colonic tumors and CEA-negative human renal cell tumors were used.
Biodistribution study of the RDC-018 peptide showed specific CEA-expressing tumor targeting with clearance via the kidneys similar to IMP288. Despite differences in renal uptake, RDC-018, with its ability to be imaged by both scintigraphic and optical methods, provided high tumor targeting and excellent TBR, illustrating the feasibility of this dual modality imaging approach.