A Prospective, Multicenter Phase II Study of the Efficacy and Feasibility of 15-minute Panitumumab Infusion Plus Irinotecan for Oxaliplatin- and Irinotecan-refractory, KRAS Wild-type Metastatic Colorectal Cancer (Short Infusion of Panitumumab Trial)

Abstract

Background: In some recently updated clinical guidelines, the fully humanized monoclonal antibody panitumumab, combined with irinotecan, has been recommended as an optional third-line chemotherapy for KRAS wild-type metastatic colorectal cancer (mCRC). The present prospective, multicenter phase II study evaluated the effectiveness and safety of short 15-minute panitumumab infusions.

Patients and methods: From January 2011 to December 2011, patients with KRAS wild-type mCRC were enrolled at 8 centers. The key eligibility criteria were age ≥ 20 years and resistance or intolerance to irinotecan, fluoropyrimidine, and oxaliplatin. All patients received 6 mg/kg of panitumumab and 150 mg/m² or the previous tolerated dose of irinotecan, biweekly, until disease progression or unacceptable toxicity. The initial panitumumab infusion was 60 minutes, followed by a 30-minute infusion and then 15-minute infusions. The primary endpoint was the confirmed response rate using Response Evaluation Criteria In Solid Tumors, version 1.0. The secondary endpoints were progression-free survival, overall survival, and toxicity. The trial is registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN no. 000004647).

Results: Of the 43 patients, the median age was 62 years (range, 32-75 years), 58% were male, and the Eastern Cooperative Oncology Group performance status was 0 to 1. The total response rate was 37.2% (95% confidence interval [CI], 23.0-53.3), and the confirmed response rate was 18.6% (95% CI, 8.4-33.4). The median progression-free and overall survival were 5.8 months (95% CI, 3.3-8.4 months) and 13.6 months (95% CI, 10.8-16.5 months), respectively. The most frequent grade 3/4 toxicities were anorexia (12%), leukopenia (9%), and neutropenia (9%). Nine patients did not reach the 15-minute infusion, primarily because of disease progression. No infusion-related reactions were observed.

Conclusion: The short 15-minute panitumumab infusion regimen was well tolerated, without compromising safety or efficacy in patients with KRAS wild-type, oxaliplatin- and irinotecan-refractory mCRC.

Keywords: Anti-EGFR therapy; Convenience of outpatient; Fully humanized monoclonal antibody; Infusion-related reaction; mCRC.