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

A Phase 3, Open-Label, Randomized Study of BGB-16673 Compared to Investigator's Choice in Patients With Relapsed/Refractory Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma Previously Exposed to Covalent BTK Inhibitors

The 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 or chlorambucil plus obinutuzumab) 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).

Chronic lymphocytic leukemia and small lymphocytic lymphoma are types of blood cancer that affects people around the world. People with CLL and SLL suffer from enlarged lymph nodes, spleen, or liver, or have symptoms like night sweats, weight loss and fever. They have shorter life expectancy compared to healthy people. There is an urgent need for new treatment to prolong life and control disease-related symptoms.

In this study, participants with R/R CLL or SLL who were previously exposed to a covalent BTKi will receive BGB-16673 or the investigator's choice of bendamustine plus rituximab or high-dose methylprednisolone plus rituximab or chlorambucil plus obinutuzumab. The main purpose of this study is to compare the length of time that participants live without their CLL or SLL worsening between those participants who receive BGB-16673 versus the investigator's choice of treatment. Approximately 150 participants will be included in this study in Mainland China and Taiwan. Participants will be randomly allocated to receive either BGB-16673 or the investigator's choice of treatment.

Inclusion Criteria:

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

Exclusion Criteria:

1. Known prolymphocytic leukemia or history of, or currently suspected, Richter's transformation
2. 2. Prior autologous stem cell transplant (unless ≥ 3 months after transplant) or chimeric antigen receptor-T cell (unless ≥ 6 months after cell infusion)
3. History of severe allergic reactions or hypersensitivity to the active ingredient and excipients of study treatment (BGB-16673, bendamustine, rituximab, chlorambucil, or obinutuzumab)
4. Current or history of central nervous system involvement
5. History of ischemic stroke or intracranial hemorrhage within 6 months before first dose of study drug
6. History of confirmed progressive multifocal leukoencephalopathy.
7. Active fungal, bacterial, and/or viral infection requiring parenteral systemic therapy
8. Clinically significant cardiovascular disease

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.