Inclusion Criteria:

- Diagnosis of T-LGL leukemia or NK-LGL leukemia that is associated with at least one
of the following four conditions:

1. severe neutropenia less than 500/mm³

2. neutropenia associated with recurrent infections, including one severe infection
requiring hospitalization or two or more infections requiring antibiotic therapy

3. symptomatic anemia with significant fatigue with a score of greater than 1 on
the Eastern Cooperative Oncology Group (ECOG) Performance Status Scale; dyspnea
on exertion, but able to walk one flight of stairs without stopping (less than
grade 1 respiratory symptoms); cardiac symptoms including worsening of angina or
new onset of chest pain

4. transfusion-dependent anemia

- Participants with T-LGL leukemia: CD3+ or CD57+ cells greater than 300/mm³, or CD8+
cells greater than 650/mm³; and evidence of clonal T-cell receptor gene rearrangement

- Participants with NK-LGL leukemia: CD56+ or CD16+ NK cells greater than 750/mm³

- Normal kidney and liver function, as determined by the following laboratory results:
total bilirubin less than or equal to 2.0 mg/dl; AST (SGOT) and ALT (SGPT) less than
or equal to 2.5 times the upper limit of normal; and creatinine less than or equal to
2.0 mg/dl

- Willing to discontinue use of MTX, Cy, or cyclosporine for 1 month prior to study
entry

- Life expectancy of greater than 2 years

- Score of 0, 1, or 2 on ECOG Performance Status Scale (equivalent to at least 60% on
the Karnofsky Performance Scale)

- Willing to use contraception throughout the study

Exclusion Criteria:

- Previous or concurrent tumors (inactive non-melanoma skin cancer, in situ carcinoma
of the cervix, or disease-free cancer of more than 5 years is acceptable)

- Serious medical illness, other than leukemia, that would limit survival to less than
2 years

- Uncontrolled concurrent illness, including ongoing or active infection, symptomatic
congestive heart failure, unstable angina pectoris, or cardiac arrhythmia

- Psychiatric illness that may interfere with study participation

- HIV-infected and receiving antiretroviral therapy (HIV-infected individuals who are
not receiving retroviral therapy may participate)

- Receiving any other investigational study drugs

- Previously treated with tipifarnib or other inhibitors of MAPK signaling
intermediates

- History of allergic reaction to imidazoles, including clotrimazole, ketoconazole,
miconazole, econazole, fenticonazole, isoconazole, sulconazole, tioconazole, or
terconazole

- Pregnant or breastfeeding