Avelumab In Combination Regimens That Include An Immune Agonist, Epigenetic Modulator, CD20 Antagonist and/or Conventional Chemotherapy in Patients With Relapsed or Refractory Diffuse Large B-cell Lymphoma (R/R DLBCL)

Inclusion Criteria

• Key Inclusion Criteria: -Any of the following as defined by the WHO, 2016 lymphoid neoplasm classifications and histologically confirmed: - Diffuse large B-cell lymphoma (DLBCL), Not Otherwise Specified (NOS): Germinal center B-cell type (GCB), Activated B-cell type (ABC) - High-grade B-cell lymphoma (HGBCL) NOS - HGBCL with MYC and BCL2 and/or BCL6 rearrangements - T-cell histocyte-rich large B-cell lymphoma - EBV+ DLBCL, NOS - HHV8+ DLBCL, NOS Relapsed or refractory disease following at least 2 lines (and a maximum of 4 lines) of prior rituximab containing multi-agent chemotherapy which may include an autologous stem cell transplantation unless patients are not considered suitable for intensive second-line chemotherapy or autologous stem cell transplantation. Patients who are ineligible for intensive second line chemotherapy,must have received at least one prior rituximab-containing combination chemotherapy regimen. Patients who are ineligible for intensive second line chemotherapy, must have received at least one prior rituximab-containing combination chemotherapy regimen. - Baseline measurable disease with at least 1 bi dimensional lesion with longest diameter (LDi) >1.5cm on CT scan which is FDG avid on PET scan. - A biopsy (archived or Screening/recent) will be collected at Screening. - At least 18years of age (or ≥20 years in Japan). - Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) 0 or 1. Key Exclusion Criteria: - Active central nervous system (CNS) lymphoma. - Prior organ transplantation including prior allogeneic SCT. - Prior therapy with an anti PD 1, anti PD L1, anti PD L2, anti CD137, or anti cytotoxic T lymphocyte associated antigen 4 (CTLA 4) antibody (including ipilimumab, tremelimumab or any other antibody, or drug specifically targeting T cell co stimulatory or immune checkpoint pathways).