A Phase 1b/2 Study of Intravenous Brincidofovir in Patients With Relapsed or Refractory Lymphoma and Relapsed or Refractory Extranodal Natural Killer/T-cell Lymphoma

Inclusion Criteria: * Patients who are histopathologically diagnosed with ENKL based on the World Health Organization (WHO) Classification of Malignant Lymphoma 5th Edition (WHO-HAEM5) (can be enrolled in the Phase 1b part and the Phase 2 part) or patients diagnosed with EBV-positive nodal T- and NK-cell lymphoma (EBV + nTNKCL), nodal T-follicular helper cell lymphoma (nTFHcL) (including angioimmunoblastic T-cell lymphoma (AITL) as defined in the WHO Classification, 4th Edition), peripheral T-cell lymphoma not otherwise specified (PTCL, NOS), anaplastic large cell lymphoma (ALCL), diffuse large B-cell lymphoma (DLBCL) (e.g., DLBCL, NOS), or adult T-Cell Leukemia Lymphoma (ATLL) (can only be enrolled in the Phase 1b part) * Patients with relapsed or refractory lymphoma and previously treated with systemic chemotherapy (history of multidrug chemotherapy including L-asparaginase such as SMILE therapy for ENKL is mandatory) who are ineligible for other systemic therapies * Patients with the following Eastern Cooperative Oncology Group (ECOG) Performance Status (PS): * Phase 1b part: 0-1 * Phase 2 part: 0-2 Exclusion Criteria: * Patients with another active malignant tumor requiring treatment * Patients with NCI-CTCAE Grade 2 or higher diarrhea (increase of 4 or more bowel movements per day compared to usual number of bowel movements) within 7 days prior to starting the first dose of BCV * Graft-Versus-Host Disease (GVHD) patients requiring immunosuppressive agents * Patients with a history of Cidofovir intolerance * Patients with a history of being diagnosed with cirrhosis