Comparison of the Treatments of Obinutuzumab + Venetoclax Versus Obinutuzumab + Chlorambucil in Patients With Chronic Lymphocytic Leukemia

Inclusion Criteria:

1. Documented previously untreated CLL according to the International Workshop on Chronic Lymphocytic Leukemia (IWCLL) criteria
2. CLL requiring treatment according to IWCLL criteria
3. Total Cumulative Illness Rating Scale (CIRS score) greater than (>) 6
4. Adequate marrow function independent of growth factor or transfusion support within 2 weeks of screening as per protocol, unless cytopenia is due to marrow involvement of CLL
5. Adequate liver function
6. Life expectancy > 6 months
7. Agreement to use highly effective contraceptive methods per protocol

Exclusion Criteria:

1. Transformation of CLL to aggressive Non-Hodgkin's lymphoma (Richter's transformation or pro-lymphocytic leukemia)
2. Known central nervous system involvement
3. Participants with a history of confirmed progressive multifocal leukoencephalopathy (PML)
4. An individual organ/ system impairment score of 4 as assessed by the CIRS definition limiting the ability to receive the treatment regimen of this trial with the exception of eyes, ears, nose, throat organ system
5. Participants with uncontrolled autoimmune hemolytic anemia or immune thrombocytopenia
6. Inadequate renal function
7. History of prior malignancy, except for conditions as listed in the protocol if participants have recovered from the acute side effects incurred as a result of previous therapy
8. Use of investigational agents or concurrent anti-cancer treatment within the last 4 weeks of registration
9. Participants with active bacterial, viral, or fungal infection requiring systemic treatment within the last two months prior to registration
10. History of severe allergic or anaphylactic reactions to humanized or murine monoclonal antibodies or known sensitivity or allergy to murine products
11. Hypersensitivity to chlorambucil, obinutuzumab, or venetoclax or to any of the excipients
12. Pregnant women and nursing mothers
13. Positive test results for chronic hepatitis B virus (HBV) infection (defined as positive hepatitis B surface antigen [HBsAg] serology) or positive test result for hepatitis C (hepatitis C virus [HCV] antibody serology testing)
14. Participants with known infection with human immunodeficiency virus (HIV) or human T-cell leukemia virus-1 (HTLV-1)
15. Requires the use of warfarin, marcumar, or phenprocoumon
16. Received agents known to be strong and moderate Cytochrome P450 3A inhibitors or inducers within 7 days prior to the first dose of study drug