Purpose: Recent multi-institutional studies have reported that children with Down syndrome (DS) and acute myeloid leukemia (AML) have a favorable outcome with less intensive chemotherapy. Based on our previous trial (

Kojima, et al:
), the Japanese Childhood AML Cooperative Study Group conducted the AML-Down protocol study designed for children with DS and AML.

Patients and Method: Between February 2000 and June 2004, 72 children (44 boys, 28 girls; median age, 1 year; range, 7 months to 7 years) were enrolled in this study. The median white blood cell count was 5,800/10−9 L. The median follow-up period was 3 years (range, 9 months to 5 years). Acute megakaryocytic leukemia (M7) was diagnosed most often (90%). The treatment regimen consisted of 5 cycles of Ara C 100mg/m2 (1-hour infusion) x 7 days, THP-ADR 25mg/m2 x 2 days, and etoposide 150mg/m2 x 3days. No prophylaxis against CNS leukemia was included.

Results: Among the 72 children, 69 achieved complete remission (CR) after 1 to 2 cycles of induction therapy, with no deaths occurring during the induction period. One of 3 patients with induction failure achieved CR after another intensified chemotherapy. Eight patients relapsed during chemotherapy. One relapsed while off therapy and successfully entered a second remission after an intensified chemotherapy, followed by an allogeneic bone marrow transplant. There was no CNS relapse alone, although 1 patient relapsed in the bone marrow and CNS simultaneously. Eight relapsed patients and 2 refractory patients died without achieving a remission. The cause of death was pneumonia in 4 patients and disease progression in 7 patients. One patient died from pneumonia during the first CR. The CR rate, 3-year survival rate, and event-free survival (EFS) rate were 97.2%, 84.4%, and 83.0%, respectively. In a univariate analysis of factors that predict EFS, we found that the presence of monosomy 7 cytogenetic abnormality at diagnosis, and response to induction therapy were predictive factors for EFS. Neither age older than 2 years nor higher white blood cell count at diagnosis were statistically significant risk factors. Children with monosomy 7 had more adverse outcomes than those without monosomy 7 (41.7% vs 86.4%, p=0.02).

Discussion: Our AML protocol specified for children with DS and AML does not include high-dose Arac and is much less intensive than other protocols used for treatment of these children. However, this less intensive regimen leads to an excellent outcome. In contrast to a previous study reported from CCG (Children’s Cancer Group) in the United States, age was not a significant risk factor. However, monosomy 7 is a poor prognostic factor in children with AML, whether or not they have DS. Our study strongly suggests that children with DS and AML can be treated successfully with a less intensive chemotherapy regimen that does not include high-dose Arac.

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