Inclusion Criteria:

- Patients must have a clinical diagnosis of myelofibrosis with myeloid metaplasia or
chronic myelomonocytic leukemia (CMML). Patients may be entered based on a prior
cytogenetic karyotype showing the absence of the Philadelphia chromosome.

- Patients may be entered prior to completion of reverse transcription-polymerase chain
reaction (RT-PCR) or fluorescent in situ hybridization (FISH) studies, but a patient
who is subsequently found to be BCR-ABL or FISH positive will be removed from
protocol treatment. FISH will only be performed on patients with a normal karyotype.
A PCR sample will be sent on all patients.

- The patients with myelodysplasia must have French-American-British (FAB) subtype
chronic myelomonocytic leukemia (CMML) defined as peripheral blood monocytosis, and
less than 30 percent blasts in the peripheral blood or the bone marrow.

- The patients with myelofibrosis with myeloid metaplasia can have one of the
following: agnogenic myeloid metaplasia (idiopathic myelofibrosis), or
post-polycythemic myeloid metaplasia (post-polycythemic myelofibrosis), or
post-thrombocythemic myeloid metaplasia.

- Estimated life expectancy of 6 months or greater.

- Serum bilirubin equal to or less than twice the upper limit of normal.

- Serum SGOT and SGPT equal to or less than twice the upper limit of normal.

- Serum creatinine equal to or less than twice the upper limit of normal.

- Age at least 18 years.

- Greater than 4 weeks from any chemotherapy (except hydroxyurea), radiotherapy,
immunotherapy, or systemic glucocorticoid therapy (non-glucocorticoid hormonal
therapy is allowed). Systemic glucocorticoid therapy for non-malignant disease is
allowed.

- The last dose of hydroxyurea must be 24 hours prior to the initiation of Gleevec.

- Greater than 2 months following bone marrow or peripheral blood stem cell
transplantation or treatment with donor lymphocyte infusion (DLI).

Exclusion Criteria:

- Uncontrolled active infection.

- Pregnancy or nursing mothers.

- Patients with myelofibrosis with myeloid metaplasia or chronic myelomonocytic
leukemia who have transformed to acute myelogenous leukemia.

- Prior treatment or diagnosis of acute myelogenous leukemia.

- Patients with Philadelphia positive cytogenetics by either peripheral blood or bone
marrow sampling.

- Eastern Cooperative Oncology Group (ECOG) performance status > 3.

- Prior exposure to Gleevec.

- Active central nervous system (CNS) disease.

- Evidence of infection with the human immunodeficiency virus.

- Active psychiatric or mental illness making informed consent or careful clinical
follow-up unlikely.