Cetuximab Alone or With Irinotecan for Resistant KRAS-, NRAS-, BRAF- and PIK3CA-wild-type Metastatic Colorectal Cancer: The AGITG Randomized Phase II ICECREAM Study

Most unresectable metastatic colon cancer remains incurable, with a median survival of less than 3 years. Molecularly targeted therapies have recently been developed; in particular, monoclonal antibodies against the epidermal growth factor receptor, which are efficacious in 40% to 60% of chemotherapy-resistant patients with wild-type KRAS. This study shows that cetuximab plus irinotecan, compared with cetuximab alone, increases the response rate and delays progression in irinotecan-resistant RAS wild-type colorectal cancer. Background: The Irinotecan Cetuximab Evaluation and Cetuximab Response Evaluation (ICECREAM) study assessed the efficacy of cetuximab monotherapy compared with cetuximab combined with chemotherapy for quadruple wild-type (KRAS, NRAS, BRAF, or P13KCA exon 20) metastatic colorectal cancer. Patients and Methods: Patients were enrolled in an open-label, multicenter, phase II trial and randomly assigned to cetuximab 400 mg/m², then 250 mg/m² cetuximab weekly, with or without irinotecan 180 mg/m² every 2 weeks. The primary endpoint was 6-month progression-free survival; secondary endpoints were response rate, overall survival, toxicity, and quality of life. Results: From 2012 to 2016, 48 patients were recruited. Two were ineligible, and 2 were not evaluable for response. Characteristics were balanced, except gender (male, 62% vs. 72%) and primary sidedness (left, 95% vs. 68%). For cetuximab compared with cetuximab-irinotecan, progression-free survival was 14% versus 41% (hazard ratio, 0.39; 95% confidence interval, 0.20-0.78; P =.008); response rate was 10% (2 partial responses) versus 38% (1 complete, 8 partial); P =.04. Grade 3 to 4 toxicities were less with cetuximab monotherapy (23% vs. 50%); global and specific quality of life scores did not differ. Conclusion: In comparison with cetuximab alone, cetuximab plus irinotecan increases the response rate and delays progression in irinotecan-resistant RAS wild-type colorectal cancer. This echoes data from molecularly unselected patients.