Biomarker-Guided First-Line Treatment Selection

Panelists discuss how biomarker-driven strategies have become central to first-line treatment selection in advanced gastric and gastroesophageal junction cancers. They describe the major biomarkers currently informing treatment—HER2, PD-L1, microsatellite instability, and mismatch repair deficiency—as key determinants of both therapeutic eligibility and expected outcomes. The emergence of targeted and immune-based therapies has substantially reshaped the standard of care, moving beyond traditional chemotherapy alone toward a more individualized and biology-driven approach.

The discussion highlights the complexity of sequencing these therapies, as biomarker expression and clinical context dictate which patients derive the most benefit from targeted or immune-based interventions. Molecular heterogeneity within gastric tumors presents further challenges, often requiring repeated or complementary testing to capture actionable alterations. The panel underscores the growing importance of multidisciplinary tumor boards in aligning pathology, oncology, and molecular diagnostics expertise to interpret results and tailor treatment plans.

Chemotherapy continues to play a foundational role in the management of biomarker-positive disease, serving either as a backbone to combination regimens or as a subsequent option when targeted pathways are exhausted. Panelists agree that optimal integration of chemotherapy and precision-based treatments depends on both molecular profiling results and patient-specific clinical factors