A Study in Previously Untreated Chronic Lymphocytic Leukemia (CLL) Subjects, Excluding Those With the 17p Deletion, to Evaluate Debulking Regimens Prior to Initiating Venetoclax Combination Therapy

Low tumor burden is defined as absolute lymphocyte count (ALC) < 25 × 10^9 /L and all lymph nodes < 5 cm per computed tomography (CT) scans.

Complete remission rate is defined as the percentage of participants achieving complete remission (CR) or complete remission with incomplete marrow recovery (CRi) as their best response based on 2008 Modified International Workshop for Chronic Lymphocytic Leukemia National Cancer Institute-Working Group (IWCLL NCI-WG) criteria.

CR required all of the following:

• Peripheral blood lymphocytes <4000/μL
• Absence of lymphadenopathy by physical examination and computed tomography scan
• No hepatomegaly or splenomegaly
• Absence of disease or constitutional symptoms (unexplained fevers >38°C, drenching night sweats, ≥10% weight loss in last 6 months)
• Blood counts above the following:

• Neutrophils >1500/μL
• Platelets >100,000/μL
• Hemoglobin >11.0 g/dL
• Bone marrow at least normocellular for age, <30% lymphocytes

CRi was defined as participants with CR who had persistent cytopenia unrelated to CLL but related to drug toxicity.

ORR is defined as the percentage of participants who achieved a best response of complete remission (CR), complete remission with incomplete marrow recovery (CRi), nodular partial remission (nPR), or partial remission (PR) based on the 2008 Modified IWCLL NCI-WG criteria at any time during the study as assessed by investigator up through the completion of the 65-week disease response assessment after the start of venetoclax. Participants who did not respond were considered non-responders.

DoR is defined as the number of days from the date of first response (CR, CRi, nPR, or PR per the 2008 Modified IWCLL NCI-WG criteria) to the date of disease progression or death, whichever occurs first. All disease progression was to be included regardless whether the event occurred during or after the participant was taking any study drug (either venetoclax, obinutuzumab, or bendamustine). Duration of response was analyzed by Kaplan-Meier (K-M) methodology.

PFS is defined as the number of days from the date of first dose of any study drug (either venetoclax, obinutuzumab, or bendamustine) to the date of disease progression or death, whichever occurs first. All disease progression was to be included regardless whether the event occurred during or after the participant was taking any study drug. Progression-free survival was analyzed by Kaplan-Meier methodology.

TTP is defined as the number of days from the date of first dose of any study drug (either venetoclax, obinutuzumab, or bendamustine) to date of disease progression. All disease progression was to be included regardless of whether the event occurred during or after the participant was taking any study drug.The distribution of the time to progression was estimated using Kaplan-Meier methodology.

OS is defined as number of days from the date of first dose of any study drug (either venetoclax, obinutuzumab, or bendamustine) to the date of death. If a participant had not died, their data was censored at the date when they were last known to be alive prior to the cutoff date.The distribution of OS was estimated using Kaplan-Meier methodology.

The level of MRD was assessed in the peripheral blood of all participants at 5 months after last dose of obinutuzumab, and at 3 months after last dose of venetoclax/end of treatment (including early study termination) to determine the rate of UMRD. Undetectable Minimal Residual Disease is defined as less than one CLL cell per 10,000 leukocytes (< 10^-4 ).