Study of Single Agent Idelalisib Followed by Idelalisib in Combination With Chemotherapy in Adults With Metastatic Pancreatic Ductal Adenocarcinoma

Key Inclusion Criteria: * The presence of metastatic pancreatic adenocarcinoma plus 1 of the following: * Histological diagnosis of pancreatic adenocarcinoma confirmed pathologically, OR * Pathologist confirmed histological/cytological diagnosis of adenocarcinoma consistent with pancreas origin * Measurable disease per response evaluation criteria in solid tumors (RECIST) v1.1 * Prior systemic chemotherapy treatment for metastatic pancreatic ductal adenocarcinoma (Arm: idelalisib single agent only) * Received one prior line of chemotherapy for metastatic pancreatic ductal adenocarcinoma (Arm: idelalisib + mFOLFOX6 only) * Adequate organ function defined as follows: * Hepatic: Total bilirubin ≤ 1.25 x upper limit of normal (ULN) (Arm: idelalisib + nab-paclitaxel ); total bilirubin ≤1.5 x ULN (Arm: single agent idelalisib and Arm: idelalisib + mFOLFOX6); aspartate transaminase (AST) serum glutamic oxaloacetic transaminase (SGOT), alanine transaminase (ALT) serum glutamic pyruvic transaminase (SGPT) \< 2.5 x ULN, and albumin \> 3.0 g/dL * Hematological: absolute neutrophil count (ANC) \> 1,500 cells/cubic millimetre (m\^3), platelet \> 100,000 cells/mm\^3, hemoglobin \> 9.0 grams/decilitre (g/dL) * Renal: Serum creatinine ≤ 1.5 x ULN OR calculated creatinine clearance (CrCl) \> 30 millilitre (ml)/min as calculated by the Cockcroft-Gault method * Able to comprehend and willing to sign the written informed consent form Key Exclusion Criteria: * Currently or previous…