Therapy of HES, PV, Atypical Chronic Myelocytic Leukemia (CML) or Chronic Myelomonocytic Leukemia (CMML), and Mastocytosis With Imatinib Mesylate

Inclusion criteria

• ✓. Participants must have 1 of the following hematopoietic malignancies: Hypereosinophilic syndrome (HES), Polycythemia vera (PV), Atypical CML or CMML with PDGF-R fusion genes, Mastocytosis, Serum bilirubin less than 2 mg%, serum creatinine less than 2 mg% unless abnormality is considered due to hematologic malignancy by investigator, Eastern Cooperative Oncology Group (ECOG) performance status \< 3, life expectancy \> 12 wks,
• ✓. continued from above. Participants must sign informed consent indicating they are aware of the investigational nature of the study, in keeping with 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 as they are referred in the relevant populations.