A Pralatrexate Study in Asian Patients With Peripheral T-cell Lymphoma After Prior Therapy

Inclusion Criteria: 1. At least 20 years of age, inclusive 2. Patients with histologically/cytologically confirmed PTCL using either: NCCN diagnosis criteria, the Revised European American Lymphoma (REAL), and World Health Organization (WHO) disease classification (PTCL histology/cytology subtypes diagnosed by site investigators, PTCL histology/cytology subtypes rechecked by study central pathology lab): 1. At least 5 patients with Peripheral T-cell lymphoma, NOS 2. At least 5 patients with Angioimmunoblastic T-cell lymphoma 3. At least 5 patients with Extranodal NK/T-cell lymphoma, nasal type 4. Enteropathy-type T-cell lymphoma 5. Hepatosplenic T-cell lymphoma 6. Subcutaneous panniculitis-like T-cell lymphoma 7. Adult T-cell lymphoma/leukemia (human T-cell leukemia virus \[HTLV\] 1+) 3. Patients with documented progressive disease (PD) failed after prior treatment 1. Patients may not have received an experimental drug as their only prior therapy 2. Patient has had at least 1 biopsy from initial diagnosis of PTCL or in the relapsed setting to confirm PTCL subtypes 3. Patient has recovered from the toxic effects of prior therapy 4. Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 2. 5. Adequate hematological, hepatic, and renal function as defined by: absolute neutrophil count (ANC) ≥ 1000/µL, platelet count ≥ 100,000/µL (and ≥ 50,000/µL for any following dose), total bilirubin ≤ 1.5 mg/dL, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 X upper limit of normal (ULN) (AST/ALT \< 5 X ULN if documented hepatic involvement with lymphoma), creatinine ≤ 1.5 mg/dL or a calculated creatinine clearance ≥ 50 mL/min. 6. Women of childbearing potential must agree to practice medically acceptable contraceptive regimen from 30 days prior to study treatment initiation until at least 30 days after the last administration of pralatrexate and must have had a negative serum pregnancy test within 14 days prior to the first day of study treatment. Patients who are postmenopausal for at least 1 year (\> 12 months since last menses) or were surgically sterilized do not require this test. 7. Men who are not surgically sterile must agree to practice a medically acceptable contraceptive regimen from study treatment initiation until at least 90 days after the last administration of pralatrexate. 8. Patient has provided written informed consent (IC) Exclusion Criteria: 1. Patient has following subtypes (histologically/cytologically confirmed) of PTCL 1. Anaplastic large cell lymphoma, ALK +/- 2. Patient has: Precursor T/NK neoplasms, with the exception of blastic NK lymphoma 3. T-cell prolymphocytic leukemia (T-PLL) 4. T-cell large granular lymphocytic leukemia 5. Mycosis fungoides and transformed mycosis fungoides 6. Sézary syndrome 7. Primary cutaneous CD30+ disorders: Anaplastic large cell lymphoma and lymphomatoid papulosis 8. Patient has: Extranodal NK/T-cell lymphoma, nasal type with local recurrence 2. Active concurrent malignancy (except for non-melanoma skin cancer or carcinoma in situ of the cervix). If there is a history of prior malignancy, the patient must be disease-free for ≥ 5 years. 3. Congestive heart failure Class III/IV according to the New York Heart Association's Heart Failure guidelines. 4. Patients with human immunodeficiency virus (HIV)-positive diagnosis and are receiving combination anti-retroviral therapy. 5. Current or the history of brain metastases or central nervous system (CNS) diseases 6. Have undergone allogeneic stem cell transplant 7. Relapsed less than 75 days from time of autologous stem cell transplant 8. Patients with uncontrolled hypertension, active uncontrolled infection, underlying medical condition including unstable cardiac disease, or other serious illness that would impair the ability of the patient to receive protocol treatment 9. Had major surgery within 2 weeks of study entry 10. Receipt of any conventional chemotherapy or radiation therapy (RT) within 4 weeks (6 weeks for nitrosoureas or mitomycin C) prior to study treatment or planned use during the course of the study 11. Receipt of corticosteroids within 7 days of study treatment, unless patient has been taking a stable dose of no more than 10 mg/day of prednisone for at least 1 month 12. Use of any investigational drug, biologic modifier, or device within 4 weeks prior to study treatment or planned use during the course of the study 13. Previous exposure to pralatrexate 14. Other conditions that investigators consider not suitable for study enrollment