[Investigation of Administration Technique of Regorafenib in Our Center].

Regorafenib is an oral multikinase inhibitor; the CORRECTtrial evaluated its efficacy in patients with metastatic colorectal cancer following disease progression with standard therapies. However, regorafenib has toxicities that develop quickly. Few studies have reported the safe dose and usage of regorafenib to avoid these adverse events in Japanese patients. We examined the side effects and safe administration technique of regorafenib in this study. We administered regorafenib to 15 patients with metastatic colorectal cancer following disease progression with standard therapies. Between August 2013 and January 2014, 5 patients received 160 mg oral regorafenib once daily on days 1-21 of a 28 day course(group A). Between February 2014 and July 2015, 10 patients received initiating therapy with 120 mg regorafenib, with the intention of increasing the dose(group B). We retrospectively assessed side effects, number of dose courses, and total dose of regorafenib in both groups. The median dosing course was 5 coureses in group B, which was more than the 1 course in group A. The median total dose was 10,800 mg in group B, which is about 4 times as much as the 2,400 mg in group A. In group B, 7 out of 10 patients (70%)were successful in the dose escalation of regorafenib from 120 to 160 mg daily over 3-5 courses. The disease control rate was 40% in both groups. The rate of adverse events of Grade 3 or higher was 60% in group A, compared to 40% in group B within 2 courses. The overall survival time was 308 days in group B, which was significantly longer than the 168 days in group A. Initiating therapy with 120 mg regorafenib with the intention of increasing the dose improves safety and allows an increase in dosing courses, as well as in the total dose of regorafenib and overall survival time.