A Phase IB, Multicenter, Open-label Dose Escalation Study of the PI3K Inhibitor BYL719 in Combination With the HSP90 Inhibitor AUY922 in Patients With Advanced or Metastatic Gastric Cancer Carrying a Molecular Alteration of PIK3CA or an Amplification of HER2. This evidence concerns the gene ERBB2 and gastric cancer.