Pembrolizumab plus chemotherapy for previously untreated, HER2-negative unresectable or metastatic advanced gastric or gastroesophageal junction (G/GEJ) adenocarcinoma: KEYNOTE-859.

TPS263Background: For patients with unresectable, locally advanced recurrent or metastatic G/GEJ cancer, the standard of care includes a fluoropyrimidine plus a platinum-based agent as first-line t...