Precision medicine for gastric cancer has taken a significant step forward with the identification of five distinct tumor microenvironments that determine whether patients will respond to immunotherapy combinations. This breakthrough could transform how oncologists select treatments for one of the world's deadliest cancers, where current immunotherapy success rates remain disappointingly low.
The NEOSUMMIT-01 trial analysis of 110 gastric cancer patients revealed that tumors cluster into five ecotypes based on their cellular composition and molecular signatures. Three ecotypes—characterized by T cell activation, tertiary lymphoid structures, and vascular normalization—showed strong responses to neoadjuvant immunochemotherapy. However, two ecotypes proved resistant: one dominated by extracellular matrix organization and another enriched with immunosuppressive macrophages. The researchers identified a specific resistance mechanism where APOA1-expressing tumor cells interact with TREM2-positive macrophages to block immune responses.
This work represents a crucial advance in cancer immunotherapy precision. Unlike previous biomarker approaches that rely on single measurements like PD-L1 expression, this multi-omic classification captures the complex interplay between tumor genetics, immune cell populations, and stromal architecture. The identification of specific biomarkers including SBS19 mutational signatures, HLA-B*15:02 variants, and FGFR pathway activity provides clinically actionable tools for treatment selection. For gastric cancer, which affects over one million people annually worldwide with five-year survival rates below 35%, this stratification approach could significantly improve outcomes by directing patients toward therapies most likely to succeed while sparing others from ineffective treatments and associated toxicities.