Patients are in 2 cohorts:

Cohort 1: dexamethasone, methotrexate, ifosfamide, pegaspargase, and etoposide (modified SMILE) chemotherapy regimen alone and pembrolizumab in children, adolescents, and young adults with advanced stage NK lymphoma and leukemia Cohort 2: combining pralatrexate (PRX) (Cycles 1, 2, 4, 6) and brentuximab vedotin (BV) (Cycles 3, 5) to cyclophosphamide, doxorubicin, and prednisone in children, adolescent, and young adults with advanced peripheral T-cell lymphoma (non-anaplastic large cell lymphoma or non-NK lymphoma/leukemia) .

Both groups proceed to allogeneic stem cell transplant with disease response.

Inclusion Criteria:

• Patients must weigh at least 10 kilograms at the time of the study enrollment.
• Diagnosis

Newly diagnosed patients with histologically proven mature T- and NK- cell neoplasms:

COHORT 1

• Aggressive NK cell leukemia (ICD-O code 9948/3)

• Extranodal NK/T-cell lymphoma, nasal type (ICD-O code 9719/3) COHORT 2

• Enteropathy-associated T-cell lymphoma (ICD-O code 9717/3)

• Hepatosplenic T-cell lymphoma (ICD-O code 9716/3)

• Peripheral T-cell lymphoma, non-otherwise specified (ICD-O code 9702/3)

• Angioimmunoblastic T-cell lymphoma (ICD-O code 9705/3)

• Other mature T- and NK-cell neoplasm histologies will considered after case-by-case discussion with Study Chairs and executive Vice-Chair Patients with lymphoma must have stage III or IV disease (See Appendix III for Staging).

  • Organ Function Requirements

Adequate liver function defined as:

• Total bilirubin ≤ 1.5 x upper limit of normal (ULN) for age.
• ALT (SGPT) < 3 x ULN for age.

Adequate cardiac function defined as:

• Shortening fraction of ≥ 27% by echocardiogram, or
• Ejection fraction of ≥ 50% by radionuclide angiogram.

Adequate pulmonary function defined as:

• Patients with a history of pulmonary dysfunction must have no evidence of dyspnea at rest, no exercise intolerance due to pulmonary insufficiency, and a pulse oximetry > 92% while breathing room air unless current dysfunction is due to the lymphoma, in which case the patient is eligible.

Exclusion Criteria:

• Alk+ or Alk- Anaplastic Large Cell Lymphoma (ALCL)
• Patients with active CNS disease.
• Patients with stage I or stage II disease (See Appendix III for Staging).
• Patients who have received any prior cytotoxic chemotherapy for the current diagnosis of NHL.
• Previous steroid treatment and/or radiation treatment are not allowed unless they are used for emergency management. Patients who have received emergency irradiation and/or steroid therapy will be eligible only if started on protocol therapy not more than one week from the start of radiotherapy or steroids.
• Female patients who are pregnant. Pregnancy tests must be obtained in girls who are post menarchal.
• Lactating females, unless they have agreed not to breastfeed their infants.
• Patients with Down syndrome.
• Patients taking CYP3A4 substrates with narrow therapeutic indices. Patients (COHORT 2 ONLY) chronically receiving medications known to be metabolized by CYP3A4 and with narrow therapeutic indices (See Appendix V). The topical use of these medications (if applicable) is allowed.
• Patients taking CYP3A4 inhibitors. Patients (COHORT 2 ONLY) chronically receiving drugs that are known potent CYP3A4 inhibitors within 7 days prior to study enrollment (See Appendix V). The topical use of these medications (if applicable) is allowed.
• Patients taking CYP3A4 inducers. Patients (COHORT 2 ONLY) chronically receiving drugs that are known potent CYP3A4 inducers within 12 days prior to study enrollment (See Appendix V).