A phase II study of oxaliplatin reintroduction in patients pretreated with oxaliplatin and irinotecan for advanced colorectal cancer (RE-OPEN study).

Abstract

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 weeks of treatment start would be 40% and 20%, 33 patients (18 in Step I and 15 in Step II) were required with a one sided α-level of 5% and a power of 80%. Results: Between February 2011 and August 2013, 33 patients were enrolled in this study. Characteristics of patients were as follows (n=33): median age of 62 years (35-77); male/female: 19/14; ECOG PS0: 84.8%; and colon/rectum: 14/19. All patients received mFOLFOX6 regimen. The DCR after 12 weeks of treatment start was 39.4% (95% CI: 21.8-57.0%), and the primary endpoint was met. The response Rate (CR or PR) was 6.1%. The median number of courses of chemotherapy was five, and the median total dose of L-OHP was 366.9 mg/m2. The median progression free survival was 98 days and the median overall survival was 300 days. The incidence of allergic reaction was 24.4% and peripheral neuropathy was 90.9%, graded as mild to moderate events. There were no other severe adverse events and treatment related deaths. Conclusions: Reintroduction of L-OHP was effective and could be a new salvage option for patients with mCRC refractory to previous L-OHP based therapy. Clinical trial information: 000004884.