MORRIS PLAINS, N.J., May 18, 2009 (GLOBE NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today announced that a novel, improved, method for attaching fluorine-18 (F-18) to peptides has been published online in The Journal of Nuclear Medicine, ahead of print, authored by W.J. McBride, R.M. Sharkey, H. Karacay, C.A.D'Souza, E.A. Rossi, P. Laverman, C-H. Chang, O.C. Boerman, and D.M. Goldenberg. The article is entitled, "A Novel Method of 18F Radiolabeling for PET," and can be accessed at http://jnm.snmjournals.org/cgi/content/abstract/jnumed.108.060418v1.
Positron emission tomography (PET) is one of the most prominent imaging tools in diagnostic medicine. F-18 is a positron-emitting radioisotope usually given to patients as F-18 fluoro-2-deoxyglucose (F-18 FDG), a sugar analog. Increased glucose metabolism, which leads to higher uptake of F-18 FDG, is the premise of F-18 FDG PET imaging. F-18 FDG is the most widely used radiopharmaceutical in PET to determine abnormal glucose metabolism. In the United States, F-18 FDG has been approved for use in detecting certain tumors, coronary artery disease, and epilepsy. However, F-18 FDG uptake is also accelerated during inflammatory processes and in rapidly-proliferating normal cells (such as bone marrow), which may lead to false-positive results and lower specificity.
The goal of this study was to develop a rapid, stable, and efficient way of labeling peptides with F-18 for improved PET imaging of diseases with increased specificity and selectivity. However, attaching F-18 to peptides has been a time-consuming process requiring multi-step syntheses that sometimes lead to poor yields. This is a problem because the half-life of F-18 is only 110 minutes. Therefore, a more rapid and efficient way of labeling has been needed, and has now been achieved by Immunomedics' scientists. In this study, F-18 was first allowed to combine with aluminum in solution to rapidly form an aluminum-F-18 complex (AlF-18), which was then bounded to a peptide. For proof-of-principle, a peptide suitable for a bispecific antibody pretargeting method was chosen to be used in animal studies.
Mice injected with human colorectal cancer cells were pretargeted with the anti-carcinoembryonic antigen bispecific antibody, TF2, followed 16 hours later with the peptide labeled with AlF-18. Compared with animals treated with the peptides alone, tumor uptake of F-18 in pretargeted animals was 17-fold higher. More importantly, within 1 hour of AlF-18 labeled peptide injection, tumor-to-non-tumor ratio of 25:1 were obtained in most organs, allowing the specific imaging of tumor only 6 mm in diameter within 30 minutes after the injection.
"To our knowledge, this is the first report describing a direct, facile, and rapid method of binding F-18 via an aluminum conjugate. Although the feasibility of this approach was shown with a hapten-peptide used for pretargeting, we have recently extended our findings to include other receptor-binding peptides and other binding ligands of clinical interest, with improved yields," said Dr. William McBride, lead author of this study.
"Immunomedics is planning to license this new method, which is the subject of several patent applications, on a product-by-product basis, so as to make it widely available," stated Cynthia L. Sullivan, President and CEO.
This study was supported in part by a grant from the National Institute of Biomedical Imaging and BioEngineering of the U.S. National Institutes of Health.
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 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 134 patents issued in the United States and more than 300 other patents issued worldwide, protects our product candidates and technologies. For additional information on us, please visit our website at www.immunomedics.com. The information on our website does not, however, form a part of this press release.
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