Case Report: A rare case of MET-amplified gastric cancer with systemic metastasis: remarkable efficacy of crizotinib and the role of precision medicine.

Gastric cancer remains one of the most prevalent gastrointestinal malignancies, with certain subtypes, such as poorly cohesive carcinoma-including signet ring cell carcinoma (SRCC)-exhibiting aggressive progression and poor prognosis. Mesenchymal epithelial transition (MET) amplification, a relatively rare oncogenic driver in gastric cancer (~2-10.2% of cases), has been associated with resistance to conventional therapies and dismal survival (median <6 months in metastatic cases). While MET inhibitors such as crizotinib have shown efficacy in MET-altered non-small cell lung cancer (NSCLC), their role in gastric cancer remains uncertain due to tumor heterogeneity and the lack of robust clinical evidence. We report a case of a female patient with MET-amplified metastatic gastric cancer and systemic bone marrow involvement. Despite eventual disease progression, the initial response to crizotinib was remarkable, with rapid hematologic recovery (platelets: 7→216×10/L) and significant tumor regression. Although disease progression occurred after 5 months, characterized by pulmonary metastasis, biliary obstruction and multiple infections, the substantial initial benefits of crizotinib cannot be overlooked. The patient survived 8 months from diagnosis, highlighting the transient efficacy of MET inhibition and the impact of clonal evolution. This case underscores the potential and limitations of MET inhibitors in gastric cancer. Biomarker-driven selection, early resistance detection, and trials exploring crizotinib-chemotherapy/immunotherapy combinations are urgently needed to improve outcomes in this aggressive subtype.