Acute Monocytic Leukemia: Stratifying by Prognosis

Data are limited on the prognosis of children with acute monocytic leukemia (AML‐M5). A study sought to measure the value of using clinical and cytogenetic features to determine the prognosis in children with AML-M5 and establish a new risk stratification.

This study included 132 pediatric patients with AML-M5. The main outcomes were overall survival (OS) and progression-free survival (PFS). In the total cohort, five-year OS was 46.0% (95% confidence interval, 41.6-50.4). Groups with significantly lower OS were patients aged ≤3 years old (P=0.009) and those with hyperleukocytosis (P<0.001). Correlations were observed between the FMS‐like tyrosine kinase 3 (FLT3)‐internal tandem duplication (ITD) and MLL‐rearrangement carriers and fewer survivors in the overall cohort (37.1% and 36.7%, respectively), as well as in the chemotherapy-only group (19.0% and 35.0%, respectively). Increased survivorship with MLL-rearrangement was not correlated with hematopoietic cell transplantation (HCT). Upon Cox regression analysis, HCT was considered a significantly favorable factor (P=0.001); factors correlated with worse OS were hyperleukocytosis, age ≤3 years old, and bone marrow (BM) blast ≥70% in all patients (P<0.05 for all). In the chemotherapy-only group, FLT3‐ITD adversely affected OS (P=0.023); hyperleukocytosis and age ≤3 years were independently associated with worse PFS (P<0.05 for both). Compared with the standard-risk group, the high-risk group had significantly poorer outcomes (P<0.005 for both).

“We propose that children with AML‐M5 with any MLL‐rearrangementFLT3‐ITD, hyperleukocytosis, BM blast ≥70%, or age ≤3 years are classified into the high‐risk group, and HCT is beneficial especially in patients with FLT3‐ITD mutation, hyperleukocytosis, and age ≤3 years. Importantly, the choice of HCT should be made more carefully in children with MLL‐rearrangement for its suboptimal performance,” the researchers concluded.