TP53-Agnostic Lethality through Combined Pan-HDAC and CDK Inhibition in Acute Myeloid Leukemia

Tumor protein 53 (TP53)-mutated acute myeloid leukemia (AML) is characterized by poor outcomes and the quick development of treatment resistance. Here, we report that simultaneous inhibition of cyclin-dependent kinases (CDKs) and histone deacetylases (HDACs) with dinaciclib and CAY10603, respectively, eliminates the therapeutic response gap between TP53-mutant and TP53 wild-type AML. Biochemical profiling showed that CAY10603 is not only HDAC6-selective but also exhibits pan-HDAC activity similar to suberoylanilide hydroxamic acid, enabling dual targeting of transcriptional and cell cycle pathways. Across parental wild-type lines and isogenic TP53 mutants, the combination consistently suppressed clonogenic growth, induced caspase-dependent apoptosis, and downregulated key regulators such as CDK2, CDK4/6, and their cyclins, while restoring the CDK inhibitor CDKN1A/p21. In an orthotopic NSG mouse model, dinaciclib + CAY10603 significantly reduced leukemia burden and extended survival without adverse toxicity. By “normalizing” TP53-mutant AML to respond like its wild-type counterpart, this pan-HDAC/multi-CDK blockade offers a TP53-agnostic therapeutic option and warrants clinical evaluation as a strategy that remains effective regardless of baseline allelic status. Overall design: HL-60 and U937 cells were treated with HDAC inhibitors CAY10603 or SAHA for 24 hours at a concentration of 2 µM in three independent biological replicates.