Single-cell multi-omics analyses reveal EZH2 as a main driver of retinoic acid resistance in PLZF-RARA leukemia

Cancer relapse is caused by a subset of malignant cells that are resistant to treatment. To characterize resistant cells and their vulnerabilities, we studied the retinoic acid (RA)-resistant PLZF-RARA acute promyelocytic leukemia (APL) using single-cell multi-omics. We uncovered transcriptional and chromatin heterogeneity in leukemia cells and identified a subset of cells resistant to RA that depend on a fine-tuned transcriptional network targeting the epigenetic regulator Enhancer of Zeste Homolog 2 (EZH2). Epigenomic and functional analyses validated EZH2 selective dependency of PLZF-RARA leukemia and its driver role in RA resistance. Targeting pan-EZH2 activities (canonical/non-canonical) was necessary to eliminate leukemia relapse initiating cells, which underlies a dependency of resistant cells on an EZH2 non-canonical activity and the necessity to degrade EZH2 to overcome resistance.Our study provides critical insights into the mechanisms of RA resistance that allow us to eliminate treatment-resistant leukemia cells by targeting EZH2, thus highlighting a potential targeted therapy approach