Pralatrexate With Bendamustine and Total-Body Irradiation Followed by Donor Stem Cell Transplant for the Treatment of Relapsed or Refractory T-Cell Non-Hodgkin Lymphoma

Inclusion Criteria: * Age ≥ 18 years with an HCT-Comorbidity Index (CI) ≤ 5 for patients over 60 years * T-cell non-Hodgkin lymphoma (T-NHL) (2022 World Health Organization \[WHO\] criteria) including primary cutaneous T-NHL that is in untreated or unsuccessfully treated first or subsequent relapse. Patients in morphologic remission (i.e. \< 5% blasts in the bone marrow, if involved) but evidence of minimal residual disease (MRD) by positron emission tomography-computed tomography (PET-CT), multiparameter flow cytometry, cytogenetics/fluorescence in situ hybridization (FISH), or molecular means will be eligible for trial participation * The use of bridging chemotherapy prior to initiation of study treatment is allowed. Patients with symptoms/signs of hyperleukocytosis, white blood cells (WBC) \> 100,000/µL, or with concern for other complications of high tumor burden of high tumor dynamics (e.g. disseminated intravascular coagulation) can be treated with leukapheresis or may receive a cycle of salvage chemotherapy prior to start of study treatment * Karnofsky score ≥ 70; Eastern Cooperative Oncology Group (ECOG) 0-1 * Adequate cardiac function defined as absence of decompensated congestive heart failure and/or uncontrolled arrhythmia and left ventricular ejection fraction ≥ 45% * Bilirubin ≤ 2.5 x institutional upper limit of normal unless elevation is thought to be due to hepatic infiltration by lymphoma, Gilbert's syndrome, or hemolysis * Adequate pulmonary function define…