An evaluation of pembrolizumab with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy for HER2 positive gastric or gastroesophageal junction adenocarcinoma expressing PD-L1 (CPS ≥1)

Pembrolizumab plus trastuzumab and chemotherapy has established a new first-line standard of care for patients with HER2-positive, PD-L1 CPS ≥1 metastatic gastric or gastroesophageal junction adenocarcinoma. Nonetheless, primary and acquired resistance driven by HER2 heterogeneity, immune evasion, and dynamic molecular evolution remain major challenges. Next-generation HER2-targeted therapies, including bispecific antibodies, novel antibody - drug conjugates, and dual HER2 antibodies will be crucial to further improve outcomes in this population.