Chemotherapy in Treating Children With Down Syndrome and Myeloproliferative Disorder, Acute Myelogenous Leukemia, or Myelodysplastic Syndrome

OBJECTIVES: * Evaluate the efficacy of reduced-dose induction and intensification chemotherapy, in terms of remission rate, disease-free survival rate, and acute morbidity and mortality, in children with Down syndrome and acute myelogenous leukemia or myelodysplastic syndromes. * Define the understanding of the natural history of transient myeloproliferative disorder (TMD) in children with Down syndrome. * Determine whether there is a reduction of sequelae in long-term survivors after treatment with this regimen. * Determine the incidence of subsequent leukemia in patients with transient myeloproliferative disorder treated with this regimen. * Determine the predictive risk factors for developing subsequent leukemia in patients with transient myeloproliferative disorder treated with this regimen. OUTLINE: This is a multicenter study. * Group I: Patients are observed if their transient myeloproliferative disorder (TMD) does not require intervention. Patients who require therapy for TMD undergo leukapheresis or exchange transfusion for up to 3 consecutive days. If the TMD does not resolve or there is significant organ involvement, patients receive low-dose cytarabine IV continuously on days 0-4. Treatment repeats at least every 2 weeks for up to 4 courses. Patients who experience a recurrence of TMD at least 8 weeks after resolution or have refractory disease may proceed to group II for further treatment. * Group II (closed to accrual as of 6/24/04 except for patients first enrolled in group I): Patients receive induction therapy comprising cytarabine IV continuously, daunorubicin IV continuously, and oral thioguanine twice daily on days 0-3. Treatment repeats every 28 days for 4 courses. Patients with no CNS disease at diagnosis receive cytarabine intrathecally (IT) on day 0. Patients with CNS disease at diagnosis receive cytarabine IT on days 0, 5, and 7. If CNS disease persists on day 7, patients receive up to 6 courses of cytarabine IT, hydrocortisone IT, and methotrexate IT, twice weekly beginning on day 10. Patients who achieve remission after induction therapy receive 2 courses of intensification therapy, for approximately 4 months. During the first course, patients receive cytarabine IV over 3 hours twice daily on days 0, 1, 7, and 8. Patients also receive asparaginase intramuscularly on days 1 and 8. The second course of therapy comprises CNS prophylaxis. Patients with no CNS disease at diagnosis or whose CNS disease resolved by day 7 of induction therapy receive cytarabine IT on days 0, 7, and 14. Patients with persistent CNS disease on day 7 of induction therapy receive cytarabine IT, hydrocortisone IT, and methotrexate IT on days 0, 7, and 14. Patients are followed monthly for 18 months, every 3 months for 1 year, every 6 months for 2.5 years, and then annually thereafter. PROJECTED ACCRUAL: A total of 70 patients with acute myeloid leukemia or myelodysplastic syndromes will be accrued for this study within 3.2 years. A total of 88 patients with transient myeloproliferative disorder who enter remission will be accrued for this study within 5 years.