Inclusion Criteria:

        Subjects must meet all of the following inclusion criteria to participate in this study:

          1. Informed consent and HIPAA authorization for release of personal health information
             obtained.

          2. Age ≥ 18 years at the time of consent.

          3. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-2.

          4. Histological confirmation of biopsy-proven peripheral T-cell leukemia/lymphoma
             consistent with ATLL

               -  Included subtypes will be: acute, lymphomatous, and chronic unfavorable. Chronic
                  unfavorable is defined as the chronic variant with at least one of the following:
                  lactate dehydrogenase (LDH)>upper limit of normal (ULN), blood urea nitrogen
                  (BUN)>ULN, Albumin<lower limit of normal (LLN)

               -  Positive human T-lymphotropic virus-1 (HTLV-1) antibody testing with confirmatory
                  testing via Western blot, enzyme-linked immunosorbent assay (ELISA), or molecular
                  testing (PCR).

          5. Documented negative serologic testing for human immunodeficiency virus (HIV).

          6. If positive for HBV exposure or prior infection, can continue to participate in trial
             with prophylactic entecavir (for HBV). If positive for hepatitis c virus (HCV)
             exposure or active infection, can participate in trial with monitoring for liver
             function abnormalities.

          7. Demonstrate adequate organ function as defined below; all screening labs to be
             obtained within three days prior to study treatment.

             System: Renal -Calculated creatinine clearance

             Laboratory Value: ≥ 30 mL/min using the Cockcroft-Gault formula for subjects with
             creatinine levels > 2.0 x institutional ULN

             System: Hepatic - Bilirubin

             Laboratory Value: ≤ 3.0 mg/dL

             System: Hepatic - Aspartate aminotransferase (AST)

             Laboratory Value: ≤ 2.5 × ULN

             System: Hepatic - Alanine aminotransferase (ALT)

             Laboratory Value: ≤ 2.5 × ULN

          8. Females of childbearing potential must have a negative serum pregnancy test within
             three days (72 hours) prior to initiating study treatment. NOTE: Females are
             considered of child bearing potential unless they are surgically sterile (have
             undergone a hysterectomy, bilateral tubal ligation, or bilateral oophorectomy) or they
             are naturally postmenopausal for at least 12 consecutive months.

          9. Females of childbearing potential must be willing to abstain from heterosexual
             activity or to use 2 forms of effective methods of contraception from the time of
             informed consent until 24 weeks (6 months) after treatment discontinuation. The two
             contraception methods can be comprised of two barrier methods, or a barrier method
             plus a hormonal method or an intrauterine device that meets <1% failure rate for
             protection from pregnancy in the product label.

         10. Male patients with female partners must have had a prior vasectomy or agree to use an
             adequate method of contraception (i.e., double barrier method: condom plus spermicidal
             agent) starting with the first dose of study therapy through 24 weeks (6 months) after
             the last dose of study therapy.

         11. As determined by the enrolling physician or protocol designee, willingness and ability
             of the subject to understand and comply with study procedures

         12. Prior Treatment: Previously untreated or has received a maximum of one cycle of any
             combination chemotherapy (e.g. cyclophosphamide, doxorubicin, vincristine, prednisone
             (CHOP), CHOEP, DA-EPOCH, doxorubicin, cyclophosphamide, cytarabine, vincristine,
             methotrexate/Etoposide, ifosfamide, cytarabine, methotrexate (CODOX-M/IVAC),
             HyperCVAD) within 4 weeks of signing the main consent form. Additionally, a patient
             may have taken antiretroviral therapy (e.g. azidothymidine (AZT) and/or IFN) at any
             time prior to study enrollment

         13. CD30 expression determined by flow cytometry or IHC. NOTE: If CD30 testing was
             previously done on the biopsy sample from diagnosis, this information will be
             collected. If CD30 testing was not done, an archival sample from the biopsy used for
             diagnosis will be requested and tested for CD30. CD30 testing will also be done on the
             bone marrow tissue collected from the bone marrow exam. If we are unable to obtain an
             archival sample or if the bone marrow exam is negative, a new biopsy will be performed
             to confirm the diagnosis and test for CD30.

        Exclusion Criteria:

        Subjects who meet any of the following criteria should be excluded from study
        participation:

          1. Pregnant or breastfeeding (NOTE: breast milk cannot be stored for future use while the
             mother is being treated on study).

          2. Has a known additional malignancy that is active and/or progressive requiring
             treatment; exceptions include basal cell or squamous cell skin cancer, in situ
             cervical or bladder cancer, or other cancer for which the subject has been
             disease-free for at least five years.

          3. Previous exposure to brentuximab vedotin (BV).

          4. History of allergic response to BV-CHEP or its components or to any of the required
             prophylactic medications or reasonable alternatives.

          5. Symptomatic cardiac disease including ventricular dysfunction, left ventricular
             ejection fraction < 40%, symptomatic coronary artery disease or symptomatic
             arrhythmias

          6. Subjects with severe hepatic insufficiency Child-Pugh Score > 6

          7. Subjects with severe renal impairment (i.e., creatinine clearance ≤ 30 mL/min; see
             Appendix B - Renal Impairment Guidelines).

          8. Exclude patients with pre-existing neuropathy grade 2 or higher.

          9. Patients receiving prohibited medications listed in the patient handout provided in
             11.4 Appendix D: Prohibited Medications or Those to be used with Caution (ie,
             ketoconazole, itraconazole, ritonavir, macrolide antibiotics, erythromycin phenytoin,
             phenobarbital, carbamazepine, and valproic acid).

         10. Patients with a parenchymal brain lesion thought to be consistent with active lymphoma
             on screening CT/MRI. Of note, patients with cerebrospinal fluid (CSF) involvement
             alone are not excluded.