Primary objectives are to evaluate the safety profile and tolerability of oral BCX1777 in each cohort of patients with recurrent or refractory T/NK-cell malignancies and to evaluate pharmacokinetics (PK) of oral BCX1777.

Inclusion Criteria:

• Histologically documented with histopathological diagnosis from biopsy, T/NK-cell malignancies (WHO classification). Precursor T-cell lymphoblastic leukemia/lymphoma (T-ALL/T-LBL) should be excluded in this study

• A patient with recurrent, relapse or refractory T/NK-cell malignancies who has received at lease one chemotherapeutic regimen

• Age 20 or greater

• Eastern Cooperative Oncology Group(ECOG) performance status:0,1.

• Able to be hospitalized at least for 15 days from the first dose

• In the case of subject with tumor cell rate of ≤25% in bone marrow, a patient who satisfies both of the following criteria.

  • Neutrophil count: ≥1,200/mm3

  • Platelet count: ≥75,000/mm3

    • In the case of CTCL, the tumor cell rate is handled as ≤25%.

• Adequate Liver function: AST, ALT ≤ 5.0 x upper limit of normal (ULN)

• Adequate Renal function: Creatinine Clearance (using cockcroft-Gault formula) ≥ 50mL/min

• Life expectancy of at least 3 months

• A patient who has given a written informed consent prior to the start of procedures proper to this study.

Exclusion Criteria:

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