Retrospective Analysis of S-1 plus Bevacizumab as Maintenance Therapy after Induction of S-1 and Oxaliplatin (SOX) plus Bevacizumab as First-Line Chemotherapy in Patients with Metastatic Colorectal Cancer

Abstract

Background: The SOFT study was a phase III trial designed to validate the non-inferiority of S-1 and oxaliplatin (SOX) plus bevacizumab to mFOLFOX6 plus bevacizumab in terms of PFS in patients with metastatic colorectal cancer (mCRC) who had not previously received chemotherapy. In this study, we retrospectively reviewed cases in which S-1 plus bevacizumab as maintenance therapy after induction of S-1 and Oxaliplatin (SOX) plus bevacizumab as first-line chemotherapy in patients with metastatic colorectal cancer was applied in order to evaluate its efficacy and safety in clinical practice. Material and method: Among the 40 patients with mCRC at the Fuchu Hospital who received SOX plus bevacizumab as a first line treatment between August 2013 and December 2018. The eligible patients had histologically confirmed mCRC. On day 1 of each 3-week period during the study, patients in the SOX plus bevacizumab received a 7.5 mg/kg intravenous infusion of bevacizumab, followed by an intravenous infusion of 130 mg/m2 oxaliplatin. S-1 (40 - 60 mg) was administered orally two times per day from after dinner on day 1 to after breakfast on day 15, followed by a 7-day rest. Results: The median PFS was 15.0 months and median OS was 36.0 months. The response rate (RR: complete pus partial response) was 85.0%, and the disease control rate (DCR: RR plus stable disease) was 92.5%. The most common adverse events with SOX plus bevacizumab were hypertension (50%), neurosensory toxicity (50%), anorexia (32.5%), fatigue (45%), pigmentation (39%), Neutrophil count decreased (30%), and platelet count decreased (40%). The most common grade 3/4 adverse events were neurosensory toxicity (5%) and fatigue (9%). Conclusion: This study revealed that the survival benefit of S-1 and oxaliplatin (SOX) plus bevacizumab in Japanese patients with mCRC was like that observed in previous clinical trials. Therefore, S-1 and oxaliplatin (SOX) plus bevacizumab can be considered as routine first-line treatment option for patients with mCRC.