This study is being done to improve outcomes and treatment options in patients with chronic lymphocytic leukemia/small lymphocytic leukemia (CLL/SLL).

Patients will be treated with a combination of oral pills containing zanubrutinib and venetoclax. Depending on how each patient responds to treatment with the initial study drugs, a third drug called obinutuzumab may be added. Obinutuzumab is given by an intravenous (IV) infusion.

These study medications all are approved by the U.S. Food and Drug Administration (FDA) for CLL/SLL and for the treatment of different blood cancers. Zanubrutinib is approved as a monotherapy and venetoclax is approved in combination with obinutuzumab. However, the combination of these 3 drugs together are not FDA approved and are considered investigational. This combination has been previously combined and studied in CLL patients. 

Study participants will be treated for 15-23 consecutive 28-day cycles after which treatment will stop. The study team will discuss the specific dosing schedule with each participant.