FOLFOXIRI Plus Panitumumab for Left-sided RAS-wild-type Metastatic Colorectal Cancer.

BACKGROUND: Colorectal cancer (CRC) can be effectively treated with fluoropyrimidine chemotherapy doublets. The triplet chemotherapy program, FOLFOXIRI, is more effective than a doublet in randomized trials. We combined this triplet with the anti-EGFR antibody, panitumumab, as first line therapy in the appropriately targeted population: left-sided, RAS wild-type metastatic colorectal cancer. METHODS: A multicenter trial was conducted with the AGICC (Academic GI Cancer Consortium) group. Patients with stage IV or unresectable, left-sided, RAS wild-type CRC were eligible if they had measurable disease, adequate organ function and PS 0-1. Consented patients were treated with modified FOLFOXIRI and panitumumab every 2 weeks until progression or toxicity. CT scans were performed every 8 weeks. Primary endpoint was Response Rate by RECIST v1, with expectation of a RR ≥ 85%. RESULTS: 29 patients were enrolled and 27 were treated. 430 cycles were given including 7 pts with the maximum 24 cycles (median 18, range 3-24). Best response included 2 CR, 18 PR and 6 SD (RR 74%). One patient progressed at time of first assessment. Grade 3+ toxicity included neutropenia, diarrhea, rash, hypomagnesemia and hypokalemia, similar to prior reports. No patient had grade 5 toxicity. Median PFS was 17.0 months and OS was not reached but exceeds 36 months. CONCLUSION: In this small US multicenter study, utilizing FOLFOXIRI with an anti-EGFR antibody for appropriately selected patients, we note among the highest response rate and PFS reported for stage IV colon cancer.