Treatment of Advanced or Metastatic Gastric Cancer: HER2-Negative with MSI-H / dMMR Status

Patients with advanced or metastatic gastric cancer whose tumours are HER2-negative and test positive for microsatellite instability-high (MSI-H) or mismatch repair deficiency (dMMR) represent a clinically distinct subgroup with specific treatment implications. Identifying this molecular profile is essential to guide therapy selection.

Clinical Scenario

Advanced or metastatic gastric cancer — HER2-negative, microsatellite instability-high (MSI-H) / mismatch repair deficient (dMMR).

Treatment Approach

For this MSI-H/dMMR subgroup, a second-line immune checkpoint inhibitor strategy is recommended. The complete protocol specifies agent selection, sequencing criteria, and clinical decision points.

Full regimen details, dosing guidance, and the complete decision algorithm are available in the structured protocol below.

Instant Access to Structured Evidence-Based Regimens

References

DOI: 10.1016/j.annonc.2022.07.004

Pembrolizumab is recommended for second-line treatment of patients with MSI-H/dMMR gastric cancer [II, A; ESMO-MCBS v1.1 score: 3; ESCAT score: I-B].
In the phase II KEYNOTE-158 trial, pembrolizumab monotherapy was highly active in patients with previously treated advanced MSI-H gastric cancer, demonstrating an ORR of 45.8% and a median PFS of 11 months, with median OS and median duration of response not yet reached.

View source ↗