Omaveloxolone potentiates BET protein inhibition under hypoxia by disrupting metabolic and translational programs in acute myeloid leukemia cells

The inhibition of bromodomain and extra-terminal domain (BET) protein family achieved promising preclinical results as epigenetic therapy in acute myeloid leukemia (AML), although clinical activity of bromodomain inhibitor (BETi) as single agent remains limited. Combination strategies, including BETi with BCL-2 inhibition (e.g., Venetoclax), have been explored to enhance therapeutic efficacy. Our study aimed to investigate the role of hypoxia in the response of AML cells to BET inhibition in order to identify a novel therapeutic combination targeting leukemia stem-progenitor cells (LSPCs) in their niche. AML cells were treated with BETi (GSK1210151A) in hypoxia and normoxia (1% and 20% O 2 concentration, respectively) and analyzed for their transcriptional, translational and metabolomic profiles. The combination of BETi and Omaveloxolone (Oma), a clinical-stage NF-κB inhibitor approved for Friedreich’s ataxia, was evaluated through measurement of cell viability, cell death, cell cycle progression, inhibition of clonogenic capacity and transcriptional profile in cell lines (BETi: 250–500 nM, Oma: 400–600 nM) and/or primary AML samples (BETi: 250–1000 nM, Oma: 400–1200 nM). BETi retained anti-proliferative and pro-apoptotic activity at low oxygen concentration by modulating the leukemic transcriptional, translational and metabolic programs towards MYC suppression, reduced ribosome biogenesis, downregulation of hypoxia-adaptive and cholesterol biosynthesis pathways, disruption of polyamine metabolism and activation of a NF-κB signature at transcriptional and translational level, especially in hypoxic conditions, consistent with a stress-adaptive response. Accordingly, inhibition of NF-κB signaling by Oma significantly enhanced BETi efficacy against AML cell lines in both hypoxia and normoxia, reducing cell viability and increasing apoptosis. The combination also impaired clonogenic potential of primary LSPCs at both oxygen concentrations. At the molecular level, the drug combination converged to the downregulation of MYC, NF-κB transcriptional activity, the DNA replication, oxidative phosphorylation and cholesterol homeostasis signatures while forcing the expression of antioxidant genes. BET inhibition in hypoxia disrupts key biosynthetic and adaptive programs required for AML cell survival, including hypoxia-driven transcriptional networks and polyamine metabolism. Targeting NF-κB-mediated adaptive responses enhances this effect, supporting the combination of BETi and Oma as a rational therapeutic strategy. These findings provide a basis for further evaluation in phase I/II clinical trials.