Glutaminolysis is a metabolic dependency in FLT3 ITD Acute Myeloid Leukemia unmasked by FLT3 Tyrosine Kinase Inhibition

FLT3ITD are common mutations in Acute Myeloid Leukemia (AML) and carry a particularly bad prognosis. Although new generation FLT3 tyrosine kinase inhibitors (TKI) have shown promising results, the outcome of FLT3-mutated AML patients remains poor and demands the identification of novel, specific and validated therapeutic targets for this highly aggressive AML subtype. Utilizing an unbiased genome-wide CRISPR/Cas9 screen, we identify GLS, the first enzyme in glutamine metabolism, as synthetically lethal with FLT3 TKI treatment. Using complementary metabolomic and gene-expression analysis, we demonstrate that glutamine metabolism, through its ability to support both mitochondrial function and cellular redox metabolism, becomes a metabolic dependency of FLT3ITD AML, specifically unmasked by FLT3-TKI treatment. We extend these findings to AML subtypes driven by other tyrosine kinase activating mutations, and validate the role of GLS as a clinically actionable therapeutic target in both primary AML and in vivo models. Our work highlights the role of metabolic adaptations as a resistance mechanism to several TKI inhibitors, and suggests glutaminolysis as a therapeutically targetable vulnerability when combined with specific TKI in FLT3ITD and other TK activating mutation driven leukemias. Gene expression analysis by RNA-Seq of FLT3ITD mutant cell lines MV411 and MOLM13 treated with AC220 1nM vs vehicle control and of BCR-ABL mutated K562 cells treated with Imatinib 2uM vs vehicle control.