Amgen, the largest biotechnology company, announced that the US Food and Drug Administration (FDA) has accepted the Biologic License Application (BLA) for panitumumab, an investigational fully human monoclonal antibody that targets the epidermal growth factor receptor (EGFr) and has granted Priority Review. The BLA was submitted for the treatment of metastatic colorectal cancer patients who have failed prior chemotherapy, including oxaliplatin and/or irinotecan containing regimens. A Priority Review designation means that the FDA will target an Agency action within six months of the application's submission date.

Priority Review status is assigned by the FDA to those applications the Agency has deemed to have the potential to provide a significant therapeutic advance for patients. The rolling BLA submission for panitumumab was initiated in December 2005 and completed in March 2006. Panitumumab received Fast Track designation from the FDA in July 2005. In April 2006, marketing applications were submitted to the European Medicines Agency (EMEA) and Health Canada and in May 2006 in Australia and Switzerland.

Panitumumab is an investigational fully human monoclonal antibody that targets the epidermal growth factor receptor (EGFr), a protein that plays an important role in cancer cell signalling. Panitumumab, an IgG2 monoclonal antibody, binds with high affinity to the EGFr. Panitumumab was generated with XenoMouse technology, which creates a fully human monoclonal antibody that contains no murine (mouse) protein. The body's immune system can recognize the mouse protein found in chimeric and humanized antibodies as foreign and may launch an immune response. The goal of developing fully human monoclonal antibodies is to offer effective targeted therapies with minimum risk of immune response against these agents.

Panitumumab is being evaluated in clinical trials as both a monotherapy and in combination with other agents for the treatment of various types of cancer, including colorectal, lung and head and neck.

Although EGFr normally helps regulate the growth of many different cells in the body, EGFr also can stimulate cancer cells to grow. In fact, many cancer cells actually require signals mediated by EGFr for their survival. Residing on the surface of these tumour cells, EGFr is activated when naturally occurring proteins in the body, such as epidermal growth factor (EGF) or transforming growth factor alpha (TGF-alpha), bind to it. This binding changes the shape of EGFr, which, in turn, triggers internal cellular signals that stimulate tumour cell growth. Panitumumab binds to EGFr, preventing the natural ligands such as EGF and TGF-alpha from binding to the receptor and interfering with the signals that would otherwise stimulate growth of the cancer cell and allow it to survive.