Panitumumab in Japanese Patients with Unresectable Colorectal Cancer: A Post-marketing Surveillance Study of 3085 Patients

Objective: Panitumumab was approved in Japan in April 2010 for the treatment of Kirsten rat sarcoma-2 virus oncogene wild-type unresectable and recurrent colorectal cancer. We conducted a post-marketing surveillance study to evaluate the safety and effectiveness of panitumumab. Methods: After panitumumab was commercially available in Japan, all patients to be treated with panitumumab were enrolled. Data on baseline characteristics, treatment outcome, and incidence and severity of adverse drug reactions were collected. Results: In total, 3091 patients were registered. In the safety analysis set (n = 3085), panitumumab was administered as monotherapy (40.7%) or combination therapy (59.4%). The median treatment duration was 113 days (range: 1-559 days), and 451 (14.6%) patients received panitumumab for >= 10 months. The overall incidence rate of adverse drug reactions was 84.1%, and the most common adverse drug reaction was skin disorders (78.4%). The incidence rates (all grades) of interstitial lung disease, infusion reaction, electrolyte abnormalities and cardiac disorders were 1.3% (mortality rate: 0.6%), 1.5, 19.3 and 0.2%, respectively. The median survival time of patients treated with panitumumab monotherapy as the third-line, or later, therapy was 10.3 months. Conclusion: This post-marketing survey in clinical practice confirmed the safety and effectiveness of panitumumab. The benefit/risk balance for panitumumab in Japanese patients with unresectable colorectal cancer remains favorable.