Phase II Trial of S-1 and Oxaliplatin Plus Cetuximab for Colorectal Cancer Patients with Initially Unresectable or Not Optimally Resectable Liver Metastases (KSCC1002)

Background. The Kyushu Study Group of Clinical Cancer (KSCC) conducted phase II trials of KSCC1002 (UMIN000001308) concerning liver resectability after first-line treatment of initially unresectable or not optimally resectable colorectal liver metastases in a prospective, multicenter study. Methods. Patients with wild-type KRAS received 4-6 cycles of S-1 and oxaliplatin (SOX) plus cetuximab. Liver resectability was evaluated subsequently with the liver resection rate as the primary endpoint. Results. Of the 33 patients enrolled between March 2010 and July 2013, the median number of administration cycles was 4 (range 0-10). The overall response rate was 63.6 % (95 % confidence interval [CI] 45.1-79.6 %). Liver resection was possible in 16 of 33 (48.5 %) patients, and there were 13 R0 cases (39.4 %). We conducted a central review of liver resectability evaluated by five liver surgeons, and the resectability increased from 18.2 to 66.7 % after chemotherapy, based on imaging. The median overall survival for all 33 cases was 31.6 months (95 % CI 14.8-not reached). The median progression-free survival was 9.7 months (95 % CI 6.2-11.8). Conclusions. SOX plus cetuximab is safe and effective for advanced colorectal cancer with limited liver metastasis, and may lead to high liver resectability.