Efficacy of Triplet Combination Chemotherapy with Oxaliplatin, Irinotecan and Capecitabine (OCX) in Metastatic Colorectal Cancer in Relation to RAS/RAF Mutation Status: Results of a Retrospective Analysis

SummaryBackground: The triplet combination of fluorouracil, oxaliplatin and irinotecan for metastatic colorectal cancer improves efficacy at the cost of increased toxicity. Preliminary reports indicate that triplet combination regimens might improve outcome in the RAS/RAF-mutated subgroup. Patients and Methods: This retrospective analysis included 25 patients with metastatic colorectal cancer, who received treatment with OCX (oxaliplatin, irinotecan, capecitabine). The regimen consisted of oxaliplatin 70 mg/m² on days 1 and 15, irinotecan 100 mg/m² on days 8 and 22, and capecitabine 1,400 mg/m² on days 1-29 every 5 weeks. KRAS, NRAS, and BRAF mutations were determined by Sanger sequencing. Results: 23 patients received at least 1 cycle and were evaluable for efficacy. In 10 patients, a KRAS or BRAF mutation was detected. Partial remission rate was 61%, median progression-free survival 9.8 months, and median overall survival 32.9 months for all evaluable patients. No difference in efficacy was detected between the RAS/RAF wild-type and the mutant group. OCX was well tolerated with no grade 3/4 haematological events. Diarrhoea was the major non-haematological toxicity (24% grade 3). Conclusion: In this retrospective analysis, triplet chemotherapy with OCX was well tolerated and achieved encouraging efficacy in metastatic colorectal cancer irrespective of RAS/RAF mutation status.