758 Background: Re-introduction of oxaliplatin (L-OHP) for patients with metastatic colorectal cancer (mCRC) refractory to standard chemotherapy regimens including L-OHP, irinotecan (CPT-11), and fluorouracil was thought to be effective approach. We performed a single arm, open-label phase II study (UMIN ID: 000004884), and the reported results of interim analysis were promising. Methods: Patients with prior chemotherapy including L-OHP and CPT-11 achieved tumor response or stable disease during prior L-OHP based therapy, and 6 months or over from confirmed progression disease during previous L-OHP based therapy was eligible for this study. Patients received FOLFOX regimens every two weeks. Primary endpoint was disease control rate (DCR) after 12 weeks of treatment start. Tumor response was evaluated by RECIST v1.1, and DCR was defined as complete response (CR), partial response (PR) or stable disease. This trial followed a Simon’s two-stage minimax design. Assuming the expected and threshold DCR after 12...