Biweekly oxaliplatin plus S1 for Chinese elderly patients with advanced gastric or gastroesophageal junction cancer as the first-line therapy: a single-arm, phase 2 study

BACKGROUND: SOX (oxaliplatin and S1, every 3 weeks) is one of the most common first-line chemotherapy for advanced or metastatic G/GEJ (gastric or gastroesophageal junction) cancer in Asia, but it has noticeable hematological and neurological toxicity. In China, the majority of gastric cancer patients are middle-aged and elderly with poor tolerance to 3-weekly chemotherapy. Therefore, we aimed to assess efficacy and safety of biweekly SOX for Chinese advanced G/GEJ cancer patients aged ≥ 60 years as the first-line treatment in a single arm phase 2 study. METHODS: Oxaliplatin was administered intravenously on day 1 at 85 mg/m(2). S-1 was given at 80, 100 or 120 mg/day, depending on the body surface area (< 1.25 m(2), 1.25 to < 1.5 m(2), or ≥ 1.5 m(2)), twice daily, on day 1–10, every 2 weeks. The primary endpoint was objective response rate (ORR), and the secondary endpoints included progression free survival (PFS), overall survival (OS), disease control rate (DCR), duration of response (DOR) and safety. RESULTS: Between May 2016 and Sep 2018, 42 patients were enrolled. The median follow-up was 43.6 months. The ORR and DCR were 52.4% and 85.7%, respectively. The median PFS was 4.6 months (95%CI 2.486–6.714), and the median OS was 11.1 months (95%CI 8.001–14.199). The most common treatment-related adverse events (TRAEs) of any grade included thrombocytopenia (59.5%), neutropenia (57.1%), appetite loss (57.1%) and nausea (54.8%). Only two patients suffered from grade 3 TRAEs (4.8%), including neutropenia (1 patient, [2.4%]) and diarrhea (1 patient, [2.4%]). No ≥ grade 4 TRAEs occurred. CONCLUSIONS: Biweekly SOX seemed to have favorable tolerance without compromising the efficacy as the first-line therapy in Chinese elderly patients aged ≥ 60 years with advanced G/GEJ cancer. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT04694404 (5/1/2021). This study was approved by the Ethical Committee of National Cancer Center/ National Clinical Research Center for Cancer/ Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, (17–048/1303).