Preserved High Probability of Overall Survival with Significant Reduction of Chemotherapy for Myeloid Leukemia in Down Syndrome: A Nationwide Prospective Study in Japan

Background On the basis of results of previous Japanese trials for myeloid leukemia in Down syndrome (ML‐DS), the efficacy of risk‐oriented therapy was evaluated in the Japanese Pediatric Leukemia/Lymphoma Study Group AML‐D05 study. Procedure All patients received induction chemotherapy that consisted of pirarubicin, intermediate‐dose cytarabine, and etoposide. Patients who achieved complete remission (CR) after initial induction therapy were stratified to the standard risk (SR) group and received four courses of reduced‐dose intensification therapy. Patients who did not achieve CR were stratified to the high risk (HR) group and received intensified therapy that consisted of continuous or high‐dose cytarabine. Results A total of 72 patients were eligible and evaluated. One patient died of sepsis during initial induction therapy. Sixty‐nine patients were stratified to SR and two patients to HR. No therapy‐related deaths were observed during intensification therapy. The 3‐year event‐free and overall survival rates were 83.3% ± 4.4% and 87.5% ± 3.9 %, respectively. Age at diagnosis less than 2 years was a significant favorable prognostic factor for risk of relapse (P = 0.009). Conclusions The attempt of risk‐oriented prospective study for ML‐DS was unsuccessful, but despite the dose reduction of chemotherapeutic agents, the overall outcome was good, and further dose reduction might be possible for specific subgroups.