Catalytic inhibition of KAT6/KAT7 enhances the efficacy and overcomes primary and acquired resistance to Menin inhibitors in MLL leukaemia [ChiP-seq]

Targeting the MYST acetyltransferases are an exciting therapeutic opportunity in acute myeloid leukaemia (AML). Here we define the individual and combined contribution of KAT6A, KAT6B and KAT7, in range of AML models showing that although KAT6A/B inhibition is efficacious in some pre-clinical models, simultaneous targeting of KAT7, with the novel inhibitor PF-9363, markedly increases efficacy. KAT7 interacts with Menin and the MLL complex and is co-localised at chromatin to co-regulate oncogenic transcriptional programs. Focusing on MLL fusion oncoprotein (MLL-FP) AML, we show that inhibition of KAT6/KAT7 provides an orthogonal route to targeting Menin to disable the transcriptional activity of the MLL-FP. Combined inhibition rapidly evicts the MLL-FP from chromatin, potently represses oncogenic transcription and overcomes primary resistance to Menin inhibitors. Notably, KAT7 remains an important targetable dependency in acquired genetic/non-genetic resistance to Menin inhibition providing the molecular rationale for rapid clinical translation of combination therapy, particularly in MLL-FP AML.