Efficacy and safety of camrelizumab plus chemotherapy versus chemotherapy alone in patients with untreated, HER2-negative, unresectable locally advanced, or metastatic gastric cancer or gastroesophageal junction cancer: a retrospective comparative cohort study

Background: Nivolumab combined with chemotherapy has been shown to improve prognosis in patients with untreated, human epidermal growth factor receptor 2 (HER2)-negative advanced gastric cancer (GC) and programmed death ligand-1 (PD-L1) combined positive score (CPS) >= 5. However, the available firstline treatment options for advanced GC are limited. Analysis of efficacy and safety of other programmed cell death protein 1 (PD-1) antibodies combined with chemotherapy may provide alternative treatment options. Methods: This retrospective study included patients with untreated, HER2-negative, unresectable locally advanced, or metastatic GC or gastroesophageal junction (GEJ) cancer who received either camrelizumab combined with oxaliplatin plus S-1 (SOX)/capecitabine plus oxaliplatin (CapeOX) or SOX/CapOX alone between November 2020 and April 2022. The objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and safety were evaluated. Results: This study included 49 patients in camrelizumab plus chemotherapy group and 54 in chemotherapy group. The baseline clinical characteristics beyond Epstein-Barr virus (EBV) status and PD-L1 CPS had no difference between combination group and chemotherapy group. ORR and DCR were significantly higher in combination therapy group than in chemotherapy group (59.18% vs. 38.89%, P=0.048; 83.67% vs. 62.96%, P=0.018). The median PFS in combination group was significantly longer than chemotherapy group [10.03 vs. 6.24 months, hazard ratio (HR) 0.603, 95% confidence interval (CI): 0.368-0.989, P=0.045]. The OS was not mature at the time of the OS analysis, with 40% patients died. Subgroup analyses showed that PFS was longer in patients with PD- L1 CPS =1 compared with CPS <1 and in patients with a neutrophil-lymphocyte ratio (NLR) <2.38 compared with =2.38. The most common grade 3-4 treatment-related adverse events (TRAEs) were granulocytopenia (57% in combination group vs. 54% in chemotherapy group), anemia (39% vs. 33%, respectively), and thrombocytopenia (39% vs. 33%, respectively). The proportion of reactive cutaneous capillary endothelial proliferation (RCCEP, 73% vs. 0%) was higher in combination group relative to chemotherapy group; all were grades 1-2. Conclusions: Among patients treated with camrelizumab combined with chemotherapy, the clinical outcomes were superior to those patients treated with chemotherapy. However, these promising findings need to be confirmed in future clinical trials.