Inclusion Criteria:  Documented diagnosis of chronic lymphocytic leukemia (CLL) that requires treatment for CLL according to International Workshop for Chronic Lymphocytic Leukemia (iwCLL) 2018 criteria. Previously completed venetoclax + obinutuzumab (VenG) regimen as a fixed duration first-line (1L) therapy and achieved documented response, defined as complete remission, complete remission with incomplete marrow recovery, partial remission, or nodular partial remission. More than 24 months (Cohort 1) or 12-24 months (Cohort 2) have elapsed between last dose of venetoclax and disease progression after completion of 1L VenG treatment.  Exclusion Criteria:  - Received intervening treatment for CLL after previous treatment with VenG.