A 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) Inhibitors

Prior treatment

• 2\. Prior autologous stem cell transplant (unless ≥ 3 months after transplant) or chimeric antigen receptor-T cell (unless ≥ 6 months after cell infusion)
• History of ischemic stroke or intracranial hemorrhage within 6 months before first dose of study drug

Other illness

• Known prolymphocytic leukemia or history of, or currently suspected, Richter's transformation
• History of severe allergic reactions or hypersensitivity to the active ingredient and excipients of study treatment (BGB-16673, bendamustine, rituximab, chlorambucil, or obinutuzumab)
• Current or history of central nervous system involvement
• History of confirmed progressive multifocal leukoencephalopathy.
• Active fungal, bacterial, and/or viral infection requiring parenteral systemic therapy
• Clinically significant cardiovascular disease
  • NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.

• Confirmed diagnosis of CLL/SLL, requiring treatment, based on 2018 international workshop on chronic lymphocytic leukemia (iwCLL) criteria.
• Previously received treatment for CLL/SLL with a covalent BTKi.
• Measurable disease by computer tomography/magnetic resonance imaging for patients with SLL.
• Eastern Cooperative Oncology Group (ECOG) performance status 0-2
• Adequate bone marrow function
• Adequate kidney and liver function
• Adequate blood clotting function