...phase Ib/II trial of triple combination (pembrolizumab, trastuzumab, and chempotherapy) as first line therapy for HER2 positive advanced gastric and gastroesophageal junction (AGC/GEJ) cancer. Although every pts were HER2 IHC-positive, baseline HER2 amplification by NGS was related to the survival (HER2 amp (n=8) vs HER2 non-amp (n=23); mPFS, not reached vs 7.7 months, P=0.0178; mOS, not reached vs 17.9 months, P=0.044) but no other signaling pathways predicted pts’ survival.