Pancreatitis After Treatment With Encorafenib, Binimetinib, and Cetuximab for BRAF V600E Mutation-Positive Colorectal Cancer

BRAF V600E mutation-positive advanced recurrent colorectal cancer has a poor prognosis. Encorafenib, binimetinib, and cetuximab were approved for use to treat this cancer in 2020 in Japan. Here, we present the case of a patient with BRAF V600E mutation-positive colorectal cancer, who was treated with encorafenib, binimetinib, and cetuximab, and developed grade 3 pancreatitis at our hospital. After pancreatitis treatment, the drug doses were reduced from 300 mg to 225 mg of encorafenib and from 90 mg to 60 mg of binimetinib, and the treatment was resumed. Since then, no grade 3 or higher adverse events were observed. Although pancreatitis has been reported to occur after the use of encorafenib and binimetinib, it is rare. With appropriate dose reduction and attention to side effects, this regimen is considered feasible for the long-term treatment of BRAF V600E mutation-positive advanced recurrent colorectal cancer in patients aged >70 years.