Pembrolizumab in advanced gastric cancer: pioneering or prosaic?

Gastric and gastroesophageal junction (GEJ) cancers are a significant health problem worldwide with an estimated annual incidence of more than 950,000 (1). Despite newer chemotherapy regimens, the median overall survival (OS) of advanced gastric or GEJ cancer in patients treated with first-line systemic chemotherapy is typically 9–11 months (2), with a slightly better OS in the Her-2 positive subgroup when treated with Her-2 directed therapy (3). Second-line treatment usually consists of taxane or irinotecan-based cytotoxic chemotherapy and vascular endothelial growth factor receptor-2 (VEGFR-2) antibody, ramucirumab, either alone or in combination with a taxane. Once patients progress after two lines of systemic treatment, it is unknown whether there is any clinically meaningful benefit from subsequent systemic chemotherapy. Therefore, this is an area of unmet need.