Treatment of Relapsed or Refractory Diffuse Large B Cell Lymphoma With Ociperlimab (BGB-A1217) in Combination With Tislelizumab (BGB-A317) or Rituximab

Inclusion Criteria: 1. Histologically confirmed DLBCL NOS (Not Otherwise Specified), Epstein-Barr virus (EBV) + DLBCL NOS, or high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements with DLBCL histology (double/triple-hit lymphoma \[DHL/THL\]), based on the World Health Organization (WHO) 2016 classification of tumors of hematopoietic and lymphoid tissue 1. Cohort 1: participants must have positive tumor programmed cell death ligand-1 (PD-L1) immunohistochemistry (IHC) testing results as determined by local pathologist 2. Cohort 2: Participants must have negative tumor PD-L1 IHC results as determined by a local pathologist in the dose confirmation stage. The dose expansion stage can enroll participants regardless of PD-L1 expression. 2. Previously received ≥ 1 line of adequate systemic anti DLBCL therapy, defined as an anti CD20 antibody based chemoimmunotherapy for ≥ 2 consecutive cycles, unless participants had PD before Cycle 2. 3. Relapsed or refractory disease before study entry, defined as either: 1. Recurrent disease after having achieved disease remission (complete response or partial response) during or at the completion of the latest treatment regimen. 2. Stable disease or progressive disease (PD) at the completion of the latest treatment regimen. 4. Ineligible for high dose therapy/hematopoietic stem cell transplantation 5. Measurable disease as assessed by computed tomography (CT) or magnetic resonance imaging (MRI) and defined as at least 1 lymph node \> 1.5 cm in the longest diameter and/or at least 1 extranodal lesion \> 1.0 cm in the longest diameter, and measurable lesion (s) in 2 perpendicular diameters Exclusion Criteria: 1. Current or history of central nervous system lymphoma 2. Histologically transformed lymphoma 3. Receipt of the following treatment: 1. Systemic chemotherapy, targeted small molecule therapy or radiation therapy within 4 weeks (or 5 half lives, whichever is shorter) before first dose of study drug 2. Recent treatment with another monoclonal antibody within 4 weeks before first dose of study drug 3. Investigational treatment within 4 weeks (or 5 half lives, whichever is shorter) before first dose of study drug 4. Treatment with autologous stem cell transplantation within 6 months before first dose of study drug 5. Treatment with allogeneic hematopoietic stem cell transplantation or organ transplantation 6. Treatment with anti-programmed cell death protein-1 (PD-1), anti PD-L1, anti PD-L2, anti T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT), anti CTLA4 or other antibody or drug specifically targeting T cell costimulation or checkpoint pathways. 4. Active autoimmune diseases or history of autoimmune diseases that may relapse, with the following exceptions: 1. Controlled Type 1 diabetes 2. Hypothyroidism (provided that it is managed with hormone replacement therapy only) 3. Controlled celiac disease 4. Skin diseases not requiring systemic treatment (eg, vitiligo, psoriasis, or alopecia) 5. Any other disease that is not expected to recur in the absence of external triggering factors Note: Other protocol defined Inclusion/Exclusion criteria may apply