BCX-1777 may stop the growth of cancer cells by blocking the enzymes necessary for their growth. The Phase II trial is designed to study the effectiveness of BCX-1777 in treating patients who have recurrent or refractory advanced T-cell leukemia.

Patients will receive an infusion of BCX-1777 on days 1-5. Treatment may be repeated every week for up to six courses. Patients are not required to be hospitalized for the administration of BCX-1777. Some patients may continue to receive an infusion of BCX-1777 twice a week for 6 weeks.

BCX-1777 may stop the growth of cancer cells by blocking the enzymes necessary for their growth. The Phase II trial is designed to study the effectiveness of BCX-1777 in treating patients who have recurrent or refractory advanced T-cell leukemia.

Inclusion Criteria:

• Documented T-cell leukemia (precursor T-lymphoblastic leukemia/lymphomia or T-PLL)
• Failure to have responded to one or more standard regimens for their disease.
• Performance status of <=2 by Eastern Cooperative Oncology Group (ECOG) criteria
• All ages are eligible
• Life expectancy of at least 3 months
• Adequate liver function (aspartate transaminase [AST] and/or alanine transaminase [ALT] not >3 times upper limits or normal [ULN])
• Adequate kidney function (calculated creatinine clearance >50 mL/min)
• Negative urine pregnancy test within 2 to 7 days prior to the start of study treamtment in females of childbearing potential
• Females of childbearing potential and males must be willing and able to use an adequate method of contraception to avoid pregnancy for the duration of the study
• Signed informed consent/assent form (ICF) prior to start of any study specific procedures

Exclusion Criteria:

• Patients with known HIV infection or human T-cell leukemia virus type (HTLV-1)
• Patients with known Hepatitis B and/or Hepatitis C active infection
• Patients with active CMV infection
• Tumor-related central nervous system (CNS) leukemia requiring active treatment
• Active serious infection not controlled by oral or IV antibiotics
• Treatment with any investigational anti-leukemic agent or chemotherapy agent within 7 days prior to study entry, unless full recovery from side effects has occurred.
• Rapidly progressive disease with compromised organ function judged to be life-threatening by the investigator
• Concurrent treatment with other anticancer agents (corticosteroid use will not be excluded, but patient must remain on the stable dose)
• Cutaneous T-cell lymphoma (CTCL) diagnosis (including Sezary Syndrome)
• Pregnant and/or lactating women