REDWOOD CITY, Calif., Sept. 25, 2013 (GLOBE NEWSWIRE) -- OncoMed Pharmaceuticals, Inc. (Nasdaq:OMED), a clinical-stage company developing novel therapeutics that target cancer stem cells (CSCs), or tumor-initiating cells, today announced that the United States Patent and Trademark Office has granted OncoMed its third broad U.S. patent relating to antibodies that target the RSPO-LGR pathway, which is believed to be an important CSC pathway. The new patent, U.S. Patent No. 8,540,989, covers methods of treating cancer with antibodies that bind human R-spondin (RSPO) proteins and either disrupt the binding of such proteins to their receptors, the leucine-rich repeat-containing G-coupled receptors (LGRs), or disrupt RSPO activation of LGR signaling. The new patent is based on key discoveries by OncoMed scientists that RSPO proteins signal through the LGR receptor family and that antibodies that disrupt binding of RSPO proteins to LGRs or that disrupt RSPO activation of LGR signaling are potential anti-cancer agents. OncoMed has identified multiple antibodies targeting the RSPO-LGR pathway and demonstrated the activity of these antibodies in preclinical studies. OncoMed plans to file an Investigational New Drug filing on its first antibody targeting the RSPO-LGR pathway in as early as 2014. OncoMed has worldwide rights to all of its RSPO-LGR pathway programs. Two broad composition-of-matter patents related to the new patent were previously granted in the U.S. to OncoMed. The composition-of-matter patents cover human, humanized, and chimeric monoclonal antibodies that disrupt binding of RSPO proteins to LGRs or disrupt RSPO activation of LGR signaling. The claimed antibodies include both anti-RSPO antibodies and anti-LGR antibodies. Related patent applications are currently pending in the U.S., Europe, Japan, Canada, and Australia. OncoMed's patent portfolio also includes additional patent applications directed towards antibodies that target the RSPO-LGR pathway. "The RSPO-LGR pathway is increasingly considered to be one of the key pathways regulating cancer stem cells," said Paul J. Hastings, Chairman and Chief Executive Officer of OncoMed. "The grant of this additional anti-RSPO antibody patent to OncoMed further strengthens OncoMed's intellectual property position in the U.S. for antibodies targeting this key cancer stem cell pathway, including OncoMed's own anti-RSPO antibody programs."