Translating Gastric Cancer Genomics into Targeted Therapy: Mechanistic Insights from Animal Models and Patient-Derived Systems

Gastric cancer remains a leading cause of cancer-related mortality worldwide and is marked by pronounced molecular heterogeneity. Advances in genomic profiling have identified key genetic alterations, including oncogenes (HER2, PIK3CA, and MYC), tumor suppressor genes (TP53, CDH1, and ARID1A), and regulators of genome stability and cell architecture (MLH1, RHOA, and CLDN18), which have driven the development of targeted therapeutic strategies. Although genetically engineered mouse models and xenograft systems have been indispensable for functional validation and preclinical drug testing, many approaches that showed promising efficacy in animal models—such as inhibition of EGFR, MET, FGFR2, and the PI3K pathway—failed to translate into overall survival benefits in clinical trials, highlighting major translational limitations. In contrast, HER2- and CLDN18.2-targeted therapies represent rare but notable clinical successes, underscoring the importance of true oncogenic dependency, precise biomarker-driven patient selection, and robust preclinical validation. In this review, we systematically categorize gastric cancer-associated genes according to their biological functions, summarize representative animal models, and critically examine key successes and failures in clinical translation, emphasizing the need for biologically faithful models and precision-driven translational strategies.