PI3K Inhibitor BYL719 in Combination With the HSP90 Inhibitor AUY922 in Patients With Advanced or Metastatic Gastric Cancer

Inclusion Criteria: * Patients with advanced or metastatic adenocarcinoma of the stomach or gastroesophageal junction; * Patients must not have a complete gastrectomy; * gastric tumors carrying PIK3CA mutation or amplification, or HER2-overexpression, or both; * at least one but no more than three previous lines of treatment for advanced or metastatic disease; * Patients with PIK3CA mutated or amplified tumors must have failed at least one line but no more than three lines of standard chemotherapy and/or targeted agents;Patients with HER2 amplified tumor must have failed at least one line, but no more than three lines, with or without anti-HER2 therapy. All HER2 positive patients are expected to have received trastuzumab unless contraindications were present or trastuzumab was unavailable; * Performance Status (PS) ≤ 1 ; * Adequate bone marrow, liver and other organ functions and laboratory parameters; * Recovery from all AEs of previous anti-cancer therapies, including surgery and radiotherapy, to baseline or to CTCAE Grade ≤ 1, except for alopecia;Negative serum pregnancy (β hCG) test within 72 hrs before starting study treatment in all pre-menopausal women and women \< 12 months after the onset of menopause. \* Exclusion Criteria: * Progressive disease during or after prior combination treatment with PI3K-inhibitors and HSP90- inhibitors; * history of prior significant toxicity from another PI3K- or HSP90- inhibitor requiring discontinuation of treatment; * primary CNS tumor or uncontrolled CNS metastasest; * Patients who are currently receiving medication with a known risk of prolonging the QT interval or inducing Torsades de Pointes and the treatment cannot either be discontinued or switched to a different medication prior to starting study drug treatment; * Patients with diabetes mellitus requiring insulin treatment and/or with clinical signs or with fasting glucose ≥ 140 mg/dL / 7.8 mmol/L, history of clinically significant gestational diabetes mellitus or documented steroid-induced diabetes mellitus;Patients with diarrhea CTCAE Grade ≥ 2 ; * Patients with acute or chronic pancreatitis; History or current evidence of central serous retinopathy (CSR), retinal vein occlusion (RVO) or ophthalmopathy as assessed by ophthalmologic examination at baseline that would be considered a risk factor for CSR/RVO; * Impaired gastrointestinal (GI) function or GI disease that may significantly alter the absorption of oral BYL719; * Patients receiving chronic slow-release formulation of Proton Pump Inhibitors (PPI), H2-antagonists or other gastric pH elevating agents; * Treatment with therapeutic doses of coumarin-based anticoagulants (e.g., warfarin sodium, Coumadin®). Low doses of courmarin-based anticoagulants; * Patients receiving chronic or high dose corticosteroids therapy; other protocol-defined inclusion/exclusion criteria may apply.