Clonal evolution and apoptosis resistance in myelodysplastic neoplasms and acute myeloid leukemia under treatment:...

Treatment of high-risk Myelodysplastic Neoplasms (hr-MDS) and (secondary) Acute Myeloid Leukemia (AML) remains a clinical challenge. The combination of azacitidine and venetoclax (aza/ven) may improve treatment outcomes, but still fails in a significant fraction of patients. We established a single-center collection of longitudinal samples from patients with MDS and AML/sAML and performed comprehensive genetic, proteomic and functional apoptosis profiling to identify biomarkers and targetable escape mechanisms to aza/ven. Baseline genetic characterization (n = 55) identified high-risk genetic alterations, while longitudinal analyses (n = 268, mean 8.7 [3-20] timepoints) revealed distinct genetic profiles of clonal evolution. Functional BH3-profiling at treatment initiation identified heterogeneous dependencies on BCL-2 family members. Notably, high BCL-2 dependence correlated with genetic response to aza/ven and improved overall survival, whereas increased BCL-xL dependence was associated with resistance. We further identified patterns of acquired resistance, with loss of apoptotic priming and shifts in anti-apoptotic dependencies contributing to treatment failure. BH3 profiling revealed functional shifts toward MCL-1 and/or BCL-xL in individual cases, suggesting potential therapeutic targets to overcome resistance. In vitro, BCL-xL inhibition effectively counteracted resistance in increased BCL-xL dependence cases. In summary, we characterized treatment-associated clonal evolution in MDS and AML, providing insights into clinical response, disease progression and potential individualized therapeutic strategies.