S-1 and oxaliplatin (SOX) plus bevacizumab versus mFOLFOX6 plus bevacizumab as first-line treatment for patients with metastatic colorectal cancer: updated overall survival analyses of the open-label, non-inferiority, randomised phase III: SOFT study

Abstract

ObjectiveThe SOFT study previously demonstrated that S-1 and oxaliplatin (SOX) plus bevacizumab was non-inferior to l-leucovorin, fluorouracil and oxaliplatin (mFOLFOX6) plus bevacizumab in terms of the primary end point of progression-free survival (PFS) as first-line chemotherapy for metastatic colorectal cancer (mCRC). The overall survival (OS) data were immature at the time of the primary analysis.MethodsA total of 512 patients were enrolled and randomly assigned to receive either mFOLFOX6 plus bevacizumab (5 mg/kg of bevacizumab, followed by 200 mg/m2 of l-leucovorin given simultaneously with 85 mg/m2 of oxaliplatin, followed by a 400 mg/m2 bolus of 5-FU on day 1 and then 2400 mg/m2 of 5-FU as an intravenous infusion over the course of 46 hours, every 2 weeks) or SOX plus bevacizumab (7.5 mg/kg of bevacizumab, 130 mg/m2 of oxaliplatin on day 1 and 40–60 mg of S-1 two times per day for 2 weeks, followed by a 1-week rest). The primary end point was PFS. After the primary analysis, the follow-up survey was cut-off on 30 September 2013, and the final OS data were analysed.ResultsWith a median follow-up of 37.7 months, the median survival time (MST) was 29.7 months with mFOLFOX6 plus bevacizumab and 29.6 months with SOX plus bevacizumab (HR, 1.018; 95% CI 0.823 to 1.258). Median PFS was 11.7 months in the mFOLFOX6 plus bevacizumab group and 12.2 months in the SOX plus bevacizumab group (HR, 1.051; 95% CI 0.876 to 1.262; pnon-inferiority=0.0115).ConclusionOur results reconfirmed that SOX plus bevacizumab is non-inferior to mFOLFOX6 plus bevacizumab in terms of PFS. MST did not differ between the groups. SOX plus bevacizumab is considered an effective regimen for first-line chemotherapy in patients with mCRC and can be used instead of mFOLFOX6 plus bevacizumab.Trial registration numberJapicCTI-090699.