Due to challenges in recruiting eligible patients under the protocol.

This study is a multi-center, global, open-label, Phase 1b/2 clinical study, and it will be conducted at multiple study sites in several countries, including Japan, Korea, and Singapore, to reveal the safety, tolerability, dose limiting toxicity (DLT), maximum tolerated dose (MTD)/recommended Phase 2 dose (RP2D), pharmacokinetics (PK), and preliminary efficacy of BCV in patients with relapsed or refractory lymphoma and to assess the efficacy and safety of Brincidofovir (SyB V-1901, BCV) in patients with relapsed or refractory Extranodal Natural Killer/T-cell Lymphoma (ENKL).

This study consists of 2 parts and will enroll a total (maximum) of 43 male and female participants who meet the eligibility criteria (Phase 1b part: Up to 18 participants [3 to 6 participants in each of the 3 cohorts], Phase 2 part: 25 participants).

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