Session: 604. Molecular Pharmacology and Drug Resistance: Myeloid Neoplasms: Poster II
Hematology Disease Topics & Pathways:
Acute Myeloid Malignancies, AML, Research, Translational Research, drug development, Diseases, Therapies, Myeloid Malignancies
Methods: In this study, a FRET assay was used to measure the ability of MLLT inhibitors to prevent the interaction of the MLLT1 and MLLT3 YEATS domains with acetylated histones. Selectivity was assessed against other YEATS domain proteins. MLLT target gene expression was measured by qPCR in leukemia cell lines. The anti-proliferative potential of MLLT1/3 inhibitors was assessed across a broad range of leukemia and normal cell lines and compared with menin inhibitors and other standard of care compounds using a cell viability readout (total ATP quantification). Combination studies were also performed in leukemia cell lines with MLLT1/3 and menin inhibitors. The clonogenic potential of MLLT1/3 inhibitors was determined using colony formation assays. Apoptosis was measured using caspase 3/7 readout. In vivo activity was assessed in a MV4;11 subcutaneous model.
Results: We have identified novel MLLT1/3 inhibitors which block the interaction of the MLLT1 and 3 YEATS domains with acylated histones with IC50 values <100 nM. They were shown to have excellent selectivity for MLLT1/3, with no inhibition observed against two other YEATS domain proteins, YEATS2 and 4. The MLLT1/3 inhibitors were shown to inhibit the expression of MLLT target genes known to be regulated via the SEC e.g., MYC and HOXA9. These compounds profoundly inhibited the growth of MLLr fusion and NPM1 mutant leukemias, with minimal activity seen against normal cell lines. Notably, potent inhibition of cell growth in non-MLLr fusion leukemia cell lines was observed, which were not sensitive to menin inhibition. MLLT1/3 inhibitors were shown to induce apoptosis and block the clonogenic potential of leukemia cell lines. Synergy between MLLT1/3 and menin inhibitors was also observed in leukemic cell lines. MLLT1/3 inhibitors have been tested in an MV4;11 model with substantial tumour growth inhibition observed.
Conclusion: Targeting MLLT1/3 is an attractive approach and has the potential for single agent activity across a broad range of molecular defined acute leukemias, with a differential profile to menin inhibitors.
Disclosures: Pollard: Dark Blue Therapeutics: Current Employment, Current holder of stock options in a privately-held company; Bayer AG: Ended employment in the past 24 months; Grey Wolf Therapeutics: Consultancy, Current equity holder in private company. Craggs: Dark Blue Therapeutics: Current Employment, Current holder of stock options in a privately-held company; e-therapeutics PLC: Ended employment in the past 24 months. Farnie: Cancer Research Horizons: Current Employment; Dark Blue Therapeutics: Consultancy, Current holder of stock options in a privately-held company. Fawkes: Dark Blue Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Fedorov: Dark Blue Therapeutics: Consultancy, Research Funding. Gross: Dark Blue Therapeutics: Current Employment, Current holder of stock options in a privately-held company; Ashfield Excellence Academy: Other: Spouse works for Ashfield Excellence Academy which is a medical communications company working extensively with multiple biopharma partners in a variety of fields of clinical medicine. Harman: Dark Blue Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Maloney: Dark Blue Therapeutics: Current Employment, Current holder of stock options in a privately-held company; UCB: Current equity holder in publicly-traded company. Milne: Dark Blue Therapeutics: Consultancy, Current holder of stock options in a privately-held company. Simpson: Vertex: Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Ended employment in the past 24 months; AstraZeneca: Current equity holder in publicly-traded company; Dark Blue Therapeutics: Current Employment, Current holder of stock options in a privately-held company; Biogen: Current equity holder in publicly-traded company.
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