Venetoclax and Ibrutinib in Treating Patients With Chronic or Small Lymphocytic Leukemia

PRIMARY OBJECTIVE: I. Estimate therapeutic activity (best response \[complete response (CR)/complete response with incomplete recovery (CRi)\]) of combined ibrutinib and venetoclax in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic leukemia (SLL). SECONDARY OBJECTIVES: I. To determine the safety of this combination strategy. II. To estimate the time to best response with this combination. III. To determine the progression-free survival (PFS) and overall survival (OS). IV. To test pharmacodynamic endpoints and molecular interactions between these two drugs. V. To assess the therapeutic activity (best response \[CR/CRi\]) in subgroups of patients defined by immunoglobulin heavy chain variable (IGHV) mutation or fluorescence in situ hybridization (FISH) subtype. EXPLORATORY OBJECTIVE: I. To study immunological and molecular changes in the peripheral blood and the bone marrow in response to ibrutinib and venetoclax. OUTLINE: Patients receive ibrutinib orally (PO) once daily (QD) on days 1-28. Beginning on day 1 of cycle 4, patients also receive venetoclax PO QD on days 1-28. Treatment repeats every 28 days for up to 27 cycles in the absence of disease progression or unacceptable toxicity. Patients with residual disease or who are positive for minimal residual disease (MRD) after cycle 27 may continue treatment with ibrutinib. After completion of study treatment, patients are followed up every 3-6 months.