Study of Pralatrexate With Vitamin B12 and Folic Acid in Patients With Relapsed or Refractory Peripheral T-cell Lymphoma (PROPEL)

Inclusion Criteria: Histologically/cytologically confirmed PTCL, using the Revised European American Lymphoma (REAL) World Health Organization (WHO) disease classification: T/Natural Killer (T/NK) cell leukemia/lymphoma Adult T-cell lymphoma/leukemia (human T-cell leukemia virus [HTLV] 1+) Angioimmunoblastic T cell lymphoma Blastic Natural Killer (NK) lymphoma (with skin, lymph node, or visceral involvement) Anaplastic large cell lymphoma, primary systemic type PTCL - unspecified T/NK-cell lymphoma - nasal Enteropathy-type intestinal lymphoma Hepatosplenic T cell lymphoma Extranodal peripheral T/NK-cell lymphoma - unspecified Subcutaneous panniculitis T-cell lymphoma Transformed mycosis fungoides Documented progression of disease after at least 1 prior treatment. Patients may not have received experimental therapy as their only prior therapy. Patient has at least 1 biopsy from initial diagnosis or in the relapsed setting to confirm the diagnosis of PTCL. Patient has recovered from the toxic effects of prior therapy. Patients treated with monoclonal antibody therapy may be enrolled regardless of the time frame of the therapy if they have progression of disease. Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 2. ≥ 18 years of age. Adequate hematological, hepatic, and renal function. Women of childbearing potential must agree to practice a medically acceptable contraceptive regimen from study treatment initiation until at least 30 days after the last administration of pralatrexate and must have 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 or are surgically sterilized do not require this test. 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. Patient has given written informed consent. Exclusion Criteria: Patient has: Precursor T/NK neoplasms, with the exception of blastic NK lymphoma T cell prolymphocytic leukemia (T-PLL) T cell large granular lymphocytic leukemia Mycosis fungoides, other than transformed mycosis fungoides Sézary syndrome Primary cutaneous CD30+ disorders: Anaplastic large cell lymphoma and lymphomatoid papulosis Active concurrent malignancy (except 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 greater than or equal to 5 years. Congestive heart failure Class III/IV according to the New York Heart Association's Heart Failure Guidelines. Uncontrolled hypertension. Human immunodeficiency virus (HIV)-positive diagnosis and is receiving combination anti-retroviral therapy. Patient has, or history of, brain metastases or central nervous system (CNS) disease. Patient has undergone an allogeneic stem cell transplant. Patient has relapsed less than 75 days from time of an autologous stem cell transplant. 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. Major surgery within 2 weeks of study entry. 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. Receipt of corticosteroids within 7 days of study treatment, unless patient has been taking a continuous dose of no more than 10 mg/day of prednisone for at least 1 month. Use of any investigational drugs, biologics, or devices within 4 weeks prior to study treatment or planned use during the course of the study. Previous exposure to pralatrexate.