RecruitingPhase 3Drug trialA Study of BGB-16673 Compared to Investigator's Choice in Participants With Relapsed/Refractory Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma Previously Exposed to Covalent Bruton Tyrosine Kinase (BTK) InhibitorsThe purpose of this study is to investigate the efficacy and safety of BGB-16673 compared with investigator's choice (bendamustine plus rituximab or high-dose methylprednisolone plus rituximab) in participants with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) previously exposed to covalent Bruton tyrosine kinase inhibitor(s) (cBTKi).