Outcome of Childhood Acute Megakaryoblastic Leukemia: Children's Cancer Hospital Egypt 57357 Experience.

INTRODUCTION: Acute megakaryoblastic leukemia is a rare subtype of pediatric acute myeloid leukemia (AML) with poor outcomes in patients with non-Down syndrome. The reported outcomes have been poor, and the prognostic factors have not been clearly determined.

PATIENTS AND METHODS: To evaluate the prognostic significance of various cytogenetic abnormalities and minimal residual disease status determined by flow cytometry after induction I, we retrospectively analyzed the data of 80 patients with non-Down syndrome with a diagnosis of M7 AML treated at Children's Cancer Hospital Egypt (CCHE-57357) from July 2007 through December 2016.

RESULTS: Of the 80 patients, 15 died during induction I and were excluded from the survival analysis. The overall survival, event-free survival, and cumulative incidence of relapse at 2 years was 52.6% ± 12.7%, 45.2% ± 12.3%, and 31.8% ± 11.5% respectively. Of the 90 patients, 61 had cytogenetic abnormalities, including trisomy 19,13q, trisomy 8, complex karyotype, t(1;22), KMT2A rearrangements, and trisomy 21. None of these had an effect on the outcomes. In addition, 34 patients had minimal residual disease < 0.1% after induction I, but the difference did not reach statistical significance. Patients with a delayed time to recovery (possibly due to myelofibrosis) had worse outcomes compared with those with early recovery (47% ± 19.2% vs. 63.2% ± 21.9%, respectively).

CONCLUSION: Acute megakaryoblastic leukemia in patients with non-Down syndrome has a poor outcome with no clearly defined prognostic factors. However, future directions to risk stratify and tailor therapy should include assessment of the tumor biology according to the molecular pathways and study of the pathogenesis of myelofibrosis in this disease, which could affect the prognosis.