Inetetamab combined with S-1 and oxaliplatin as first-line treatment for human epidermal growth factor receptor 2-positive gastric cancer.

Background: Patients with human epidermal growth factor receptor 2 (HER2)-positive advanced gastric cancer have poor outcomes. Trastuzumab combined with chemotherapy is the first-line standard treatment for HER2-positive advanced gastric cancer. Inetetamab is a novel anti-HER2 drug, and its efficacy and safety in gastric cancer have not yet been reported.

Aim: To evaluate the efficacy and safety of the S-1 plus oxaliplatin (SOX) regimen combined with inetetamab as a first-line treatment for HER2-positive advanced gastric cancer.

Methods: Thirty-eight patients with HER2-positive advanced gastric cancer or gastroesophageal junction adenocarcinoma were randomly divided into two groups: One group received inetetamab combined with the SOX regimen, and the other group received trastuzumab combined with the SOX regimen. After 4-6 cycles, patients with stable disease received maintenance therapy. The primary endpoints were progression-free survival (PFS) and overall survival (OS), and the secondary endpoints were the objective response rate, disease control rate, and adverse events (AEs).

Results: Thirty-seven patients completed the trial, with 18 patients in the inetetamab group and 19 patients in the trastuzumab group. In the inetetamab group, the median PFS was 8.5 months, whereas it was 7.3 months in the trastuzumab group (P = 0.046); this difference was significant. The median OS in the inetetamab group vs the trastuzumab group was 15.4 months vs 14.3 months (P = 0. 33), and the objective response rate was 50% vs 42% (P = 0.63), respectively; these differences were not significant. Common AEs included leukopenia, thrombocytopenia, nausea, and vomiting. The incidence rates of grade ≥ 3 AEs were 56% in the inetetamab group and 47% in the trastuzumab group (P = 0.63), with no significant difference.

Conclusion: In the first-line treatment of HER2-positive advanced gastric cancer, inetetamab and trastuzumab showed comparable efficacy. The inetetamab group showed superior PFS, and both groups had good safety.