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.