The primary objective of this study is to evaluate the effects of idelalisib with obinutuzumab versus the combination of chlorambucil and obinutuzumab on progression-free survival (PFS) in participants with previously untreated chronic lymphocytic leukemia (CLL).

An increased rate of deaths and serious adverse events (SAEs) among participants with front-line CLL and early-line indolent non-Hodgkin lymphoma (iNHL) treated with idelalisib in combination with standard therapies was observed by the independent data monitoring committee (DMC) during regular review of 3 Gilead Phase 3 studies. Gilead reviewed the unblinded data and terminated those studies in agreement with the DMC recommendation and in consultation with the US Food and Drug Administration (FDA). All front-line studies of idelalisib, including this study, were also terminated.

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.

Qualified external researchers may request IPD for this study after study completion. For more information, please visit our website at http://www.gilead.com/research/disclosure-and-transparency.

18 months after study completion

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After conclusion of the study and without prior written approval from Gilead, investigators in this study may communicate, orally present, or publish in scientific journals or other media only after the following conditions have been met:

• The results of the study in their entirety have been publicly disclosed by or with the consent of Gilead in an abstract, manuscript, or presentation form; or
• The study has been completed at all study sites for at least 2 years