• Diagnosis: Histologically confirmed aggressive B cell NHL including the following types defined by WHO 2008:

‣ Diffuse large B cell lymphoma (DLBCL); OR

⁃ primary mediastinal (thymic) large B cell lymphoma; OR

⁃ transformation of follicular lymphoma (TFL), marginal zone lymphoma to DLBCL; OR

⁃ high grade B-cell Lymphoma NOS will also be included

• Patients must be considered high-risk lymphoma (defined as LDH greater than upper limit of normal per institutional cut-off) at or within two weeks of leukapheresis.

• Subjects must have received at least and a maximum one prior line of therapy for LBCL indication (i.e subjects receiving second line standard of care Axi-Cel will be enrolled in this study).

• At least 1 measurable lesion on PET-CT or CT scan. If the only measurable disease is lymph-node disease, at least 1 lymph node should be ≥ 1.5 cm.

• Age 18 years or older

• Eastern cooperative oncology group (ECOG) performance status of 0 or 1. ECOG 2 permitted if performance status is solely attributed to lymphoma.

• Normal Organ and Marrow Function

‣ ANC ≥ 1,000/uL

⁃ Platelet count ≥ 75,000/uL

⁃ Adequate renal, hepatic, pulmonary and cardiac function defined as:

• Creatinine clearance (as estimated by Cockcroft Gault Equation) ≥ 60 mL/min

∙ Serum ALT or AST ≤ 2.5 x ULN (except in subjects with liver involvement by lymphoma)

∙ Total bilirubin ≤ 1.5 mg/dl, except in subjects with Gilbert's syndrome.

∙ Cardiac ejection fraction ≥ 40%, no evidence of pericardial effusion as determined by an Echocardiogram.

⁃ No clinically significant pleural effusion or ascites

⁃ Baseline oxygen saturation \> 92% on room air

• Ability to understand and the willingness to sign the written IRB-approved informed consent document. Subjects unable to give informed consent will not be eligible for this study.

• 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)

⁃ Contraception: Subjects of child-bearing or child-fathering potential must be willing to practice birth control from the time of enrollment on this study and for twelve (12) months after receiving the preparative lymphodepletion regimen.

⁃ If prior CD19 directed therapy, demonstrates CD19 positivity by biopsy (Flow cytometry or immunohistochemistry per the institutional criteria)

⁃ Prior therapy washout of at least 2 weeks or 5 half-lives, whichever is shorter, must have elapsed since any prior systemic therapy at the time the subject is planned for leukapheresis