Retrospective analysis of PD-1 antibody combined with oxaliplatin and S-1/capecitabine as first-line treatment in elderly Chinese patients with HER2-negative advanced or recurrent gastric cancer

Evidence regarding whether elderly patients (≥ 70 years) with HER2-negative advanced or recurrent gastric cancer could benefit from immunotherapy combined with oxaliplatin -based chemotherapy are limited due to the strict selection criteria of age in most clinical trials. Therefore, the aim of this study was to evaluate the safety and efficacy of PD-1 antibody (Nivolumab or Sintilimab) combined with SOX/XELOX in elderly patients with unresectable advanced or recurrent HER2-negative gastric cancer retrospectively. This retrospective observational study was designed and reported in accordance with the STROBE guidelines. Patients ≥ 70 years, ECOG 0∼2, have adequate organ function, at least one measurable lesion, life expectancy > 3 months and no prior chemotherapy except postoperative adjuvant therapy > 6 months before enrollment received nivolumab or sintilimab plus SOX/XELOX for a maximum of 6 cycles, following maintenance therapy with nivolumab or sintilimab plus capecitabine or S-1 until disease progression, intolerable toxicity, consent withdrawal, or for up to 24 months. The efficacy endpoints included ORR, DCR, PFS and OS. Toxicity was evaluated and graded each cycle according to the National Cancer Institute’s Common Terminology Criteria for Adverse Events (version 5.0). Between Feb, 2021 and Dec, 2022, a total of 37 patients were enrolled. Median age was 74.0 years (range, 70–86y). The ORR and DCR were 54.1% and 94.6%, respectively. As data cutoff of April 15, 2024, the median follow-up was 22.5 months. The median PFS was 12.7 months (95% CI: 10.2–14.1) and median OS was 18.3 months (95% CI 14.6 to not reached). The 12-months PFS rates was 56.8%. The 12-months and 18-months OS rates was 75.7% and 56.8%. In subgroup analysis, the median PFS was 11.9 months (95% CI 9.0–15.1) in nivolumab group ( n = 14) and 12.8 months (95% CI 9.4–15.0) in sintilimab group ( n = 23). The 12-month PFS estimate was similar (57.1% vs. 56.5%). No significant difference was observed in the two group ( p = 0.938). In addition, compared to nivolumab group, the ORR was higher in sintilimab group (65.2% vs. 35.7%) and the DCR was a little lower (91.3% vs. 100%). The most common grade 3 or higher treatment-related adverse events were decreased platelet count (13.5%) and hypokalemia (10.8%). PD-1 antibody plus SOX/XELOX appears to be an effective and well-tolerated regimen for first-line treatment in elderly Chinese patients with HER2-negative advanced or recurrent gastric cancer.