Immunomedics, Inc., a biopharmaceutical company primarily focused on the development of monoclonal antibody-based products for the targeted treatment of cancer, autoimmune and other serious diseases, reported the issuance of US Patent 7,919,273 on April 5, 2011, with expiration on July 21, 2029.

This patent describes structural variations of antibodies resulting in improved therapeutic properties. It claims a method of improving a chimeric or humanized anti-CD20 antibody or antigen-binding fragment comprising at least one amino acid substitution in one of the antigen-binding arms, including the substitution of an aspartate for asparagine at Kabat position 101 of the antibody heavy chain.

The substitution results in an improved property for killing target lymphocytes or lymphoma cells expressing CD20 by one or more mechanisms of action. This specifically involves veltuzumab, the company's proprietary, 2nd generation, humanized anti-CD20 antibody evaluated as both an intravenous and as a subcutaneous formulation in patients with Non-Hodgkin's Lymphomas (NHL), chronic lymphocytic leukaemia, and immune thrombocytopenia. The company has more than 10 issued US and foreign patents related to veltuzumab.

Immunomedics is collaborating with Nycomed, who received the exclusive, worldwide rights to develop, manufacture and commercialise the subcutaneous formulation of veltuzumab for the treatment of all non-cancer indications. Nycomed is planning to initiate a phase II study of the subcutaneous formulation of veltuzumab in patients with rheumatoid arthritis during this year.

“This structure-function change differentiates veltuzumab from other anti-CD20 antibodies, and based on preclinical and clinical therapy studies in lymphomas, it appears to have a high potency, even at very low doses,” commented Cynthia L Sullivan, president and CEO. “Veltuzumab is ready for phase III, registration trials in oncology, so gaining long-term patent protection is very important commercially,” she added.