US Food and Drug Administration approval: Panitumumab for epidermal growth factor receptor-expressing metestetic colorectal carcinoma with progression following fluropyrimidine-, oxelipletin-, and irinotecen-containing chemotherapy regimens

Purpose: To describe the Food and Drug Administration review and marketing approval considerations for panitumumab (Vectibix) for the third-line treatment of patients with epidermal growth factor receptor-expressing metastatic colorectal carcinoma. Experimental Design: Food and Drug Administration reviewed a single, open-label, multicenter trial in which 463 patients with epidermal growth factor receptor-expressing metastatic colorectal cancer who had progressed on or following treatment with a regimen containing a fluoropyrimidine, oxaliplatin, and irinotecan were randomized (1:1) to receive best supportive care (BSc) with or without panitumumab (6 mg/kg every other week) administered until disease progression or intolerable toxicity. Progression and response were confirmed by an independent review committee masked to treatment assignment. At progression, patients in the BSc-alone arm were eligible to receive panitumumab. Results: Although median progression-free survival (PFS) was similar in both treatment arms (similar to 8 weeks), the mean PFS was similar to 50% longer among patients receiving panitumumab than among those receiving BSC alone (96 versus 60 days, respectively) and the objective response rate in patients receiving panitumumab was 8%. However, no difference in overall survival was shown between the two study arms. Conclusions: Panitumumab received accelerated approval based on improvement in PFS and an independently confirmed response rate of 8%, similar to that observed with other active agents at this advanced stage of disease. Confirmation of clinical benefit will be required for full approval.