Phase 1 Study of BGB-21447, a Bcl-2 Inhibitor, in Mature B-Cell Malignancies

Inclusion Criteria 1. Confirmed diagnosis per WHO guidelines of one of the following: Cohort A: Relapsed/refractory (R/R) Diffuse large B-cell lymphoma (DLBCL)(excluding high-grade B-cell lymphomas with translocations of MYC and Bcl-2 and/or Bcl-2; primary cutaneous DLBCL, leg type; gray zone lymphoma; and primary mediastinal large B-cell lymphoma) R/R Follicular lymphoma (FL): R/R Marginal zone lymphoma (MZL) Transformed B-Cell non-Hodgkin lymphoma (NHL) Cohorts B and C: R/R CLL/SLL diagnosis that meets the International Workshop on Chronic Lymphocytic Leukemia (IWCLL) criteria 2. Measurable disease by computed tomography (CT)/magnetic resonance imaging (MRI), CLL: at least 1 lymph node > 1.5 cm in longest diameter and measurable in 2 perpendicular dimensions or clonal lymphocytes on flow cytometry DLBCL, FL, MZL, or SLL: at least 1 lymph node > 1.5 cm in longest diameter OR 1 extranodal lesion > 1.0 cm in the longest diameter, measurable in 2 perpendicular dimensions. For MZL, isolated splenomegaly is considered measurable. Exclusion Criteria: Prior malignancy (other than the disease under study) within the past 2 years, except for curatively treated basal or squamous skin cancer, superficial bladder cancer, carcinoma in situ of the cervix or breast, or localized Gleason score ≤ 6 prostate cancer Known central nervous system involvement by lymphoma/leukemia Known history or currently suspected Richter's syndrome Prior autologous stem cell transplant < 3 months before the first dose of study drug. Or prior chimeric antigen receptor T-cell (CAR-T) therapy < 3 months before the first dose of study drug Prior allogeneic stem cell transplant. Major surgery < 4 weeks before the first dose of study treatment Use of the following substances prior to the first dose of the study drug: Any biologic and/or immunologic-based therapy(ies) ≤ 28 days before the first dose of study drug Any systemic chemotherapy or radiation therapy ≤ 14 days before the first dose of study drug Any targeted small molecule agents ≤ 14 days before the first dose of study drug Corticosteroid given with antineoplastic intent ≤ 7 days before the first dose of study drug. Short course of systemic corticosteroid treatment for control of lymphomarelated symptoms is allowed prior to enrollment, provided it is tapered off within 5 days after initiation of study treatment. Any treatment with a strong/moderate cytochrome P450 (CYP)3A inhibitor or inducer ≤ 14 days (or 5 half-lives for inhibitors, whichever is longer) before the first dose of study drug OR requiring long-term use of strong CYP3A inhibitors or inducers NOTE: Other Inclusion/Exclusion criteria may apply.