The United States Patent and Trademark Office (USPTO) has granted OncoMed Pharmaceuticals third broad US patent relating to antibodies that target the RSPO-LGR pathway, which is believed to be an important CSC pathway.

The new 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 programmes.

Two broad composition-of-matter patents related to the new patent were previously granted in the US 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 US, 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 US for antibodies targeting this key cancer stem cell pathway, including OncoMed's own anti-RSPO antibody programmes."

Cancer stem cells, or CSCs, are the subpopulation of cells in a tumour responsible for driving growth and metastasis of the tumour. CSCs, also known as tumour-initiating cells, exhibit certain properties which include the capacity to divide and give rise to new CSCs via a process called self-renewal and the capacity to differentiate or change into the other cells that form the bulk of the tumour. Common cancer drugs target bulk tumor cells but have limited impact on CSCs, thereby providing a path for recurrence of the tumour. OncoMed's product candidates target CSCs by blocking self-renewal and driving differentiation of CSCs toward a non-tumorigenic state, and also impact bulk tumour cells. OncoMed believes its product candidates are distinct from the current generations of chemotherapies and targeted therapies, and have the potential to significantly impact cancer treatment and the clinical outcome of patients with cancer.

OncoMed Pharmaceuticals is a clinical-stage company focused on discovering and developing novel therapeutics targeting cancer stem cells.