Treatment of Advanced or Metastatic Gastric Cancer: HER2-Negative, Not MSI-High, PD-L1 CPS Below 5

This protocol covers patients with advanced or metastatic gastric cancer whose tumours are HER2-negative, are not microsatellite instability-high (MSI-H), and have a PD-L1 combined positive score (CPS) below 5. This molecular profile excludes eligibility for HER2-targeted agents and immune checkpoint options that apply to higher CPS or MSI-H subgroups, requiring a distinct therapeutic strategy.

In this setting, following prior lines of therapy, a specific oral nucleoside analogue combination is the recommended third-line option. The complete regimen details, sequencing guidance, and criteria for alternative approaches are contained in the full structured protocol.