A Phase II, Multi-Center Open-Label, Repeat-Dose of Forodesine Hydrochloride (BCX-1777) Infusion in Patients With Advanced T-Cell Leukemia With an Option of Long-Term Forodesine Hydrochloride (BCX-1777) Use

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