Acute myeloid leukemia drug resistance: targetable nodes and the clinical trajectory of small-molecule inhibitors

Acute myeloid leukemia (AML) is paradigmatic for therapeutic resistance driven by genetic heterogeneity, epigenetic plasticity and microenvironmental protection. Over the past decade, six targeted or pathway-directed small molecules-midostaurin, gilteritinib, quizartinib, ivosidenib, enasidenib, venetoclax and glasdegib-have changed frontline and relapsed/refractory (R/R) practice in genomically defined subgroups or in patients unfit for intensive chemotherapy. Yet primary refractoriness and early relapse remain common, frequently <i>via</i> adaptive rewiring of apoptotic dependencies, clonal evolution and differentiation resistance. Here we integrate mechanistic insights with clinical evidence to: (i) map resistance biology onto targetable nodes (apoptosis control; signalling kinases; chromatin/lineage programmes; RNA splicing; DNA-damage response; nuclear export; niche adhesion and innate immune evasion); (ii) summarise the clinical trajectory and current limits of approved and emerging small molecules (including menin and LSD1 inhibitors); (iii) propose rules for rational doublets and triplets that are biologically orthogonal yet clinically tolerable; (iv) outline a regulatory timeline for key AML small molecules; and (v) prioritise where drug development should go next, including next-generation BH3 toolkits, clonal-pressure-aware designs, minimal residual disease (MRD)-adapted trials and therapy guided by dynamic functional profiling. The review closes with cross-platform challenges-myelosuppression, infectious risk, resistance monitoring and trial design-and a pragmatic framework for moving beyond incrementalism toward durable control and cure.