Zanubrutinib and Venetoclax in CLL (ZANU-VEN)

This study is testing the combination of zanubrutinib (a BTK inhibitor) and venetoclax (a BCL-2 inhibitor) in people with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) — slow-growing blood cancers — who have received prior treatment. **You may be eligible if...** - You are 18 years of age or older - You have confirmed CLL or SLL and require treatment because your disease has relapsed after at least one prior therapy - Depending on which study cohort you qualify for, you may or may not have had prior treatment with BTK or BCL-2 inhibitor drugs - Your blood counts, liver, and kidney function are within acceptable ranges - You are in reasonably good health (ECOG ≤ 2) **You may NOT be eligible if...** - You have previously received both a BTK inhibitor and a BCL-2 inhibitor - You have severe heart problems (e.g., uncontrolled arrhythmia) - You have active serious infections - You are pregnant or planning to become pregnant Talk to your doctor to see if this trial is right for you.