‣ Eligible subjects will be considered for inclusion in this study if they meet the following criteria:

• Relapsed or refractory diffuse large B-cell lymphoma, primary mediastinal B-cell lymphoma, transformed indolent B-cell lymphomas and high-grade B-cell lymphoma

• Receive standard of care treatment with an FDA-approved anti-CD19 autologous CAR T-cell product, outside of a clinical trial

• ≥ 18 years of age

• Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2

• Achievement of PR according to Lugano 2014 response criteria 30 days after CAR T-cell therapy

• At least 30 days must have elapsed since CAR T-cell therapy infusion

• No evidence of CD19 expression after CAR T-cell therapy infusion is required for enrolment

• No additional anti-tumoral therapy, with the exclusion of palliative radiotherapy, must have been received after CAR T-cell therapy

• Absolute neutrophil count (ANC) of ≥ 1.0×109/L without growth factor support for 3 days prior to screening assessment.

⁃ Platelet count of ≥ 50×109/L without transfusion for 3 days prior to screening assessment.

⁃ Creatinine clearance (as estimated by Cockcroft Gault) ≥ 30 mL/min

⁃ Serum alanine transaminase (ALT) or aspartate transaminase (AST) ≤ 2.5 upper limit of normal (ULN)

⁃ Total bilirubin ≤2 mg/dL, except in subjects with Gilbert's syndrome.

⁃ Cardiac ejection fraction ≥ 45% with no evidence of clinically significant pericardial effusion

⁃ Baseline oxygen saturation \> 92% on room air

⁃ No evidence or suspicion of lymphoma actively involving the central nervous system (CNS)

⁃ Females of childbearing potential must have a negative serum or urine pregnancy test (females who have undergone surgical sterilization or who have been postmenopausal for at least 2 years are not considered to be of childbearing potential)

⁃ Resolution of any previous CRS and/or ICANS to grade 0.