A Study to Evaluate the Safety and Efficacy of BGB-16673 Compared to Pirtobrutinib in Adults With Relapsed/Refractory Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

Inclusion Criteria:

• Confirmed diagnosis of CLL or SLL, requiring treatment, based on 2018 iwCLL criteria

• Previously received treatment for CLL/SLL with a covalent Bruton tyrosine kinaseinhibitor (cBTKi). Patients should have disease relapsed after or refractory to atleast 1 line of therapy including a cBTKi.

• Participants with SLL must have measurable disease by computed tomography/magneticresonance imaging, defined as ≥ 1 lymph node > 1.5 cm in longest diameter andmeasurable in 2 perpendicular diameters.

Exclusion Criteria:

• Known prolymphocytic leukemia or history of, or currently suspected, Richter'stransformation.

• History of known bleeding disorder such as hemophilia A, hemophilia B, vonWillebrand disease, or history of spontaneous bleeding requiring blood transfusionor other medical intervention

• History of ischemic stroke or intracranial hemorrhage within 6 months before firstdose of study drug

• Prior exposure to any Bruton tyrosine kinase (BTK) protein degraders or noncovalentBruton tyrosine kinase inhibitor (ncBTKi).

• Current or history of central nervous system involvement including the brain, spinalcord, leptomeninges, and cerebrospinal fluid (as documented by imaging, cytology, orbiopsy) by CLL/SLL

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