A Study of Zanubrutinib (BGB-3111) Versus Ibrutinib in Participants With Relapsed/Refractory Chronic Lymphocytic Leukemia

Open to people ages 18 years and up

1. Confirmed diagnosis of CLL or SLL that meets the 2008 IWCLL criteria
2. CLL/SLL requiring treatment per 2008 IWCLL criteria
3. Relapsed or refractory to at least 1 prior systemic therapy for CLL/SLL
4. Measurable disease by CT/magnetic resonance imaging (MRI)
5. ECOG performance status of 0, 1, or 2
6. Life expectancy ≥ 6 months
7. Adequate bone marrow function
8. Adequate renal and hepatic function

1. Known prolymphocytic leukemia or history of, or currently suspected, Richter's transformation
2. Clinically significant cardiovascular disease.
3. Prior malignancy within the past 3 years, except for curatively treated basal or squamous cell skin cancer, non-muscle-invasive bladder cancer, carcinoma in situ of the cervix or breast
4. History of severe bleeding disorder or history of spontaneous bleeding requiring blood transfusion or other medical intervention
5. History of stroke or intracranial hemorrhage within 180 days before first dose of study drug
6. Severe or debilitating pulmonary disease
7. Active fungal, bacterial, and/or viral infection requiring systemic therapy
8. Known central nervous system involvement by leukemia or lymphoma

9. Known infection with HIV or active viral hepatitis B or C infection

   10. Moderate or severe hepatic impairment, ie, Child-Pugh class B or C 11. Major surgery within 4 weeks of the first dose of study drug 12. Prior treatment with a BTK inhibitor 13. Toxicity from prior anticancer therapy that has not recovered to ≤ Grade 1 14. Pregnant or lactating women 15. Vaccination with a live vaccine within 35 days prior to the first dose of study drug 16. Hypersensitivity to zanubrutinib, ibrutinib, or any of the other ingredients in either

   drug

   17. Concurrent participation in another therapeutic clinical trial NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.