Inhibition of ADSS2-mediated de novo AMP biosynthesis resensitizes acute myeloid leukemia to BH3 mimetics

De novo purine synthesis is required to promote tumor growth; however, its role in therapy resistance remains elusive. Here, through a dynamic BH3-priming based CRISPR-Cas9 screen, we found that deletion of ADSS2, which encodes for an enzyme functioning in de novo AMP synthesis, re-sensitizes drug resistant acute myeloid leukemia (AML) cells to BH3 mimetics. Single-cell sequencing and metabolomics analyses reveal that high ADSS2 activity in leukemia samples including those with TP53 aberrations inversely correlates with venetoclax responsiveness. Further, we developed anADSS2 antagonist, exhibiting synergism with BH3 mimetics in preclinical AML models. Mechanistically, sensitization to BH3 mimetics mediated by ADSS targeting was associated with downregulated AMPK activity, which governs mitochondrial homeostasis. AMPK activity in resistant cells promotes mitophagy to eliminate damaged mitochondria upon BH3 mimetics treatment. These data demonstrate that AMP synthesis governs venetoclax resistance, and that combining ADSS targeting with BH3 mimetic treatment could represent a promising approach against AML.