Dona Flor and her two husbands: Discovery of novel HDAC6/AKT2 inhibitors for myeloid cancer treatment.

The treatment of hematological cancers with hybrid kinase and histone deacetylase (HDAC) inhibitors represents a novel strategy to overcome acquired drug resistance. We curated half-maximal inhibitory concentration (IC50) datasets from the ChEMBL database, including 13 cancer cell lines (72 h cytotoxicity by MTT), inhibitors of 38 kinases, and 10 HDAC isoforms identified through target fishing and literature review. Rigorous biological and chemical curation produced datasets ranging from 76 to 8173 compounds, depending on the target. Random Forest classification models were developed, with 14 achieving over 80 % predictability in five-fold external cross-validation. A library of 30 hybrid kinase/HDAC analogs was screened across these models, and fragment-contribution maps were generated to guide structure-activity relationship analysis and optimization. Nine representative hybrids were synthesized and biologically evaluated, yielding high hit rates in K562 (62.5 %), MV4-11 (75.0 %), MM1S (100 %), NB-4 (62.5 %), U937 (75.0 %), and HDAC6 (86.0 %) models. This effort identified compounds 6b and 6k as potent anticancer agents, with IC50 values of 0.2-0.8 μM across three cancer cell lines. Their activity was associated with HDAC6 inhibition below 2 nM, blockade of AKT2 phosphorylation at 2 μM, and synergistic reversal of venetoclax resistance in two cancer models. These findings validate our modeling approach for predicting hybrid inhibitors and highlight 6b and 6k as promising leads for hematological cancer therapy.