Longitudinal single-cell analysis reveals treatment-resistant stem and mast cells with potential treatments for pediatric AML.

Pediatric acute myeloid leukemia (pAML) is a heterogeneous malignancy driven by diverse cytogenetic mutations. While identification of cytogenetic lesions improved risk stratification, prognostication remains inadequate with 30% of standard-risk patients experiencing relapse within 5 years. To deeply characterize pAML heterogeneity and identify poor outcome-associated blast cell profiles, we performed an analysis on 708,285 cells from 164 bone marrow biopsies of 95 patients and 11 healthy controls. The longitudinal analysis on cell abundances at the time of disease diagnosis, end of induction, and relapse identified treatment resistant stem-like blast cells specific to RUNX1::RUNX1T1, FLT3-ITD, and CBFB::MYH11 patients that are associated with poor outcomes. Treatment resistant blast cells from RUNX1::RUNX1T1 were found to associate with T cell exhaustion, while those from FLT-ITD utilized enriched antioxidant metabolism to persist through treatment. Interestingly, the analysis also identified novel mast cell-like pAML associated with treatment resistance and poor outcomes. Deconvolution of ex vivo treatment data and subsequent in vitro validation identified bortezomib (RUNX1), ponatinib, and venetoclax (FLT3) as specifically potent against treatment resistant blasts from the respective cytogenetic groups. Our findings indicate immature and mature pAML subtypes are promising biomarkers for enhanced patient risk stratification and identifies targeted agents to increase their clearance after treatment.