Efficacy and Safety of Idelalisib in Combination With Obinutuzumab Compared to Chlorambucil in Combination With Obinutuzumab for Previously Untreated Chronic Lymphocytic Leukemia

Key Inclusion Criteria: * Not a candidate for fludarabine therapy based on either: 1. creatinine clearance \< 70 mL/min, or 2. Cumulative Illness Rating Scale score \> 6, by assessment of the investigator * Diagnosis of B-cell CLL, with diagnosis established according to International Workshop on Chronic Lymphocytic Leukemia (IWCLL) * No prior therapy for CLL other than corticosteroids for disease complications. * CLL that warrants treatment * Presence of measurable lymphadenopathy * Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 2 Key Exclusion Criteria: * Known histological transformation from CLL to an aggressive lymphoma (ie, Richter transformation) * Known presence of myelodysplastic syndrome * Evidence of ongoing systemic bacterial, fungal, or viral infection at the time of randomization * Ongoing liver injury * Ongoing drug-induced pneumonitis * Ongoing inflammatory bowel disease * History of prior allogeneic bone marrow progenitor cell or solid organ transplantation * Ongoing immunosuppressive therapy other than corticosteroids * Concurrent participation in another therapeutic clinical trial * Undergone major surgery within 30 days prior to randomization * Known hypersensitivity or intolerance to any of the active substances or excipients in the formulations for idelalisib, obinutuzumab, or chlorambucil * History of non-infectious pneumonitis * Received last dose of study drug on another therapeutic clinical trial within 30 days prior to randomization Note: Other protocol defined Inclusion/Exclusion criteria may apply.