KRAS Expression Complements Genomic Profiling in Identifying Therapeutic Vulnerability in Gastric Cancer

Gastric cancer (GC) remains a major therapeutic challenge. Although alterations in the RAS pathway occur in over 50% of tumors, only a limited proportion are clinically actionable. We investigated whether KRAS expression complements genomic profiling for patient stratification and therapeutic vulnerability in GC.

Comprehensive genomic profiling was performed in 19 Taiwanese GC patients and compared with TCGA-STAD data (n = 434). KRAS mRNA expression and overall survival were evaluated by meta-analysis of 13 independent cohorts (n = 2,521). Protein-level validation was performed by immunohistochemistry in an independent cohort (n = 121). Functional KRAS dependency and response to combined MEK/SHP2 inhibition were assessed in eight GC cell lines.

KRAS amplification was entirely contained within the KRAS-high population, whereas most KRAS-high tumors lacked detectable amplification. High KRAS expression was associated with poorer overall survival (HR 1.23, p = 0.001) and remained an independent prognostic factor after multivariable adjustment (adjusted HR 1.24, p = 0.003). Protein-level analysis showed a concordant trend. KRAS expression correlated strongly with functional dependency (R² = 0.88, p = 0.005), was enriched in MSI and CIN subtypes, and identified cell lines with enhanced sensitivity to combined MEK/SHP2 inhibition.

KRAS expression complements genomic profiling by identifying biologically relevant KRAS-dependent GCs beyond mutation or amplification alone. Integrating expression-based stratification with genomic profiling may improve patient selection for RAS pathway-directed combination therapies.