A Study to Assess the Safety and Efficacy of BGB-16673 Compared to Pirtobrutinib in Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia or Small Cell Lymphocytic Lymphoma

1. Confirmed diagnosis of CLL or SLL requiring treatment according to iwCLL 2018 criteria. 2. Prior treatment for CLL/SLL with a covalent Bruton tyrosine kinase inhibitor (cBTKi). Patients should have relapsed or been refractory after at least one prior line of therapy, including treatment with a covalent BTK inhibitor (cBTKi). For patients with SLL, there must be measurable disease defined by computed tomography/magnetic resonance imaging as ≥ 1 lymph node with a diameter of > 1.5 cm in the longest dimension and measurable in 2 perpendicular diameters.

(BASEC)

1. Known prolymphocytic leukemia, history of prolymphocytic leukemia, or current suspicion of Richter transformation. 2. Current or prior central nervous system involvement by CLL/SLL, including brain, spinal cord, leptomeninges, and cerebrospinal fluid (as documented by imaging, cytology, or biopsy). 3. History of ischemic stroke or intracranial hemorrhage within months prior to the first dose of the study drug. 4. Prior treatment with a protein degrader of Bruton tyrosine kinase (BTK) or non-covalent BTK inhibitor (ncBTKi). Patients who discontinued treatment with cBTKi solely due to toxicity are not eligible. 5. History of a known bleeding disorder such as hemophilia A, hemophilia B, or von Willebrand disease, or history of spontaneous bleeding that required a blood transfusion or other medical intervention.

(BASEC)