Panitumumab: a review of its use in metastatic colorectal cancer.

Panitumumab (Vectibix(R)) is a recombinant, fully human, IgG2 anti-epidermal growth factor receptor (EGFR) monoclonal antibody. This article reviews the clinical efficacy of intravenous panitumumab in combination with chemotherapy in the first- and second-line treatment of metastatic colorectal cancer and as monotherapy in chemotherapy-refractory metastatic colorectal cancer, as well as summarizing its pharmacological properties and tolerability. Panitumumab is indicated for use in patients with wild-type rather than mutant KRAS tumours. The efficacy of intravenous panitumumab 6 mg/kg administered every 2 weeks was examined in randomized, open-label, multicentre, phase III trials in patients with metastatic colorectal cancer. When administered as first- or second-line treatment in combination with chemotherapy, panitumumab plus chemotherapy prolonged progression-free survival to a significantly greater extent than chemotherapy alone in patients with wild-type KRAS tumours; no significant between-group difference in overall survival was seen in the second-line treatment trial. In patients with mutant KRAS tumours, progression-free survival was significantly shorter with panitumumab plus oxaliplatin-based chemotherapy than with oxaliplatin-based chemotherapy alone in the first-line treatment trial, with no significant difference between patients receiving panitumumab plus irinotecan-based chemotherapy (FOLFIRI) and those receiving FOLFIRI alone in the second-line treatment trial. In chemotherapy-refractory patients with metastatic colorectal cancer, panitumumab monotherapy plus best supportive care prolonged progression-free survival to a significantly greater extent than best supportive care alone in both the overall population and in patients with wild-type KRAS tumours, but not in those with mutant KRAS tumours; there was no significant between-group difference in overall survival. Panitumumab has an acceptable tolerability profile when administered as monotherapy or in combination with chemotherapy. It is associated with the skin-related toxicities characteristic of EGFR inhibitors and appears to have a low risk of immunogenicity. In conclusion, in patients with wild-type KRAS tumours, panitumumab is a useful option in combination with chemotherapy for the first- and second-line treatment of metastatic colorectal cancer or as monotherapy for the treatment of chemotherapy-refractory metastatic colorectal cancer.