The goal of this clinical research study is to see if Gleevec, known as imatinib mesylate (STI571), can improve the disease condition in patients with hypereosinophilic syndrome, polycythemia vera, atypical CML or CMML with PDGF-R fusion genes, or mastocytosis.

To date, 25 patients with myeloproliferative syndromes have been included in this study. Five of 9 patients with HES have responded. The efficacy of Gleevec in HES has been confirmed in at least one other study. We have also treated 5 patients with PV and two of them have experienced a reduction in the need for transfusions and at least two others have reported symptomatic improvement. A beneficial effect from Gleevec has been observed also by other investigators. Responses in mastocytosis have been reported recently in 4 of 9 patients treated. In addition, patients with atypical CML or CMML with PDGF-R fusion genes have been reported to have significant activity with imatinib. We have not identified any clinical activity in other disease categories originally included on this study. Thus, we plan to continue accrual only in the following groups: ­ HES ­ Atypical CML or CMML with PDGF-R fusion genes ­ PV ­ Mastocytosis

Genders Eligible for Study:  Both

Criteria

Patients must meet the following eligibility criteria:

• Patients must have one of the following hematopoietic malignancies: a. Hypereosinophilic syndrome (HES) b. Polycythemia vera (PV) c. Atypical CML or CMML with PDGF-R fusion genes d. Mastocytosis
• Serum bilirubin less than 2mg%, serum creatinine less than 2mg% unless abnormality is considered due to hematologic malignancy by investigator.
• ECOG Performance Status < 3. Life expectancy > 12 weeks.
• Patients must sign an informed consent indicating they are aware of the investigational nature of this study, in keeping with the policies of the hospital.
• Women of pregnancy potential must practice birth control. Women and men must continue birth control for the duration of the trial and at least 3 months after the last dose of study drug.
• Inclusion of women and minorities: As per NIH policy, women and members of minorities will be included in this protocol as they are referred in the relevant populations. There are no exclusions of women or minorities based on the study objectives.
• NYHA Class < 3.