Background:Fluoropyrimidine and oxaliplatin are widely used for patients with colorectal cancer.This phase II study was conducted to evaluate the efficacy and safety of the combination of S-1,oxaliplatin,and leucovorin(SOL) in the treatment of Chinese patients with metastatic colorectal cancer(mCRC).Methods:Eligible patients with untreated mCRC from four hospitals in China received intravenous oxaliplatin(85 mg/m2) on day 1,oral S-1 twice daily(80-120 mg per day) on day 1-7,and leucovorin twice daily(50 mg per day)simultaneously with S-1,every 2 weeks.Results and discussion:Forty patients were enrolled in our study.In total,296 cycles of SOL were administered.The overall response rate was 50.0%.At a median follow-up of 27 months,progression-free survival and overall surviva were 7.0 months(95%confidence interval[CI]6.0-10.6 months) and 22.2 months(95%CI 15.1-29.3 months),respectively.The most common grade 3/4 non-hematological adverse events were diarrhea(n = 8,20.0%),nausea(n = 3,7.5%),and vomiting(n = 3,7.5%).The most common grade 3/4 hematological toxicities were thrombocytopenia(n = 3,7.5%),neutropenia(n = 1,2.5%),and abnormal alanine transaminase/aspartate transaminase levels(n = 1,2.5%).There was one treatment-related death.Conclusions:The data indicate that the SOL regimen is effective and moderately tolerated in Chinese patients with mCRC.Trial registration:Clinical trial information:ChiCTR-TNRC-100000838 Background: Fluoropyrimidine and oxaliplatin are widely used for patients with colorectal cancer. This phase II study was conducted to evaluate the efficacy and safety of the combination of S-1, oxaliplatin, and leucovorin (SOL) in the treatment of Chinese patients with metastatic colorectal cancer (mCRC). Methods: Eligible patients with untreated mCRC from four hospitals in China received intravenous oxaliplatin (85 mg / m2) on day 1, oral S-1 twice daily (80-120 mg per day) on day 1-7, and leucovorin twice daily (50 mg per day) simultaneously with S-1 every 2 weeks. Results and discussion: Forty patients were enrolled in our study.In total, 296 cycles of SOL were administered. The overall response rate was 50.0%. At a median follow-up of 27 months, progression-free survival and overall surviva were 7.0 months (95% confidence interval [CI] 6.0-10.6 months) and 22.2 months (95% CI 15.1-29.3 months), respectively. common grade 3/4 non-hematological adverse events were diarrhea (n = 8, 20.0%), nausea (n = 3, 7.5% ), and vomiting (n = 3, 7.5%). The most common grade 3/4 hematological toxicities were thrombocytopenia (n = 3,7.5%), neutropenia (n = 1,2.5%), and abnormal alanine transaminase / aspartate transaminase There was one treatment-related death. Conclusions: The data indicate that the SOL regimen is effective and moderately tolerated in Chinese patients with mCRC. Trial registration: Clinical trial information: ChiCTR-TNRC-100000838