The Food and Drug Administration (FDA) has approved panitumumab (Vectibix) for the treatment of metastatic colorectal cancer that has progressed despite standard chemotherapy. The drug received accelerated approval after showing effectiveness in slowing tumor growth and, in some cases, reducing the size of the tumor, according to the FDA.

Panitumumab is a monoclonal antibody that binds to the epidermal growth factor receptor (EGFR) protein on some cancer cells. By binding this protein, the drug may interfere with signals that might otherwise stimulate the growth and survival of cancer cells.

Panitumumab was evaluated in a randomized, controlled clinical trial of 463 patients with metastatic colon or rectal cancer who had been treated with the drugs fluoropyrimidine, oxaliplatin, and irinotecan. The results showed a benefit for panitumumab in progression-free survival but not in overall survival.

The time to progression or death in patients taking panitumumab was 96 days versus 60 days in patients who received standard chemotherapy. Eight percent of the panitumumab group had a reduction in the size of their tumors. Panitumumab is manufactured by Amgen and may be commercially available by mid-October.