Serine Biosynthesis Is a Metabolic Vulnerability in FLT3-ITD–Driven Acute Myeloid Leukemia

Abstract

Internal tandem duplication of the FMS-like tyrosine kinase 3 gene (<i>FLT3-ITD</i>) occurs in 30% of all acute myeloid leukemias (AML). Limited clinical efficacy of FLT3 inhibitors highlights the need for alternative therapeutic modalities in this subset of disease. Using human and murine models of FLT3-ITD-driven AML, we demonstrate that FLT3-ITD promotes serine synthesis and uptake via ATF4-dependent transcriptional regulation of genes in the <i>de novo</i> serine biosynthesis pathway and neutral amino acid transport. Genetic or pharmacologic inhibition of PHGDH, the rate-limiting enzyme of <i>de novo</i> serine biosynthesis, selectively inhibited proliferation of FLT3-ITD AMLs <i>in vitro</i> and <i>in vivo</i>. Moreover, pharmacologic inhibition of PHGDH sensitized FLT3-ITD AMLs to the standard-of-care chemotherapeutic cytarabine. Collectively, these data reveal novel insights into FLT3-ITD-induced metabolic reprogramming and reveal a targetable vulnerability in FLT3-ITD AML. SIGNIFICANCE: FLT3-ITD mutations are common in AML and are associated with poor prognosis. We show that FLT3-ITD stimulates serine biosynthesis, thereby rendering FLT3-ITD-driven leukemias dependent upon serine for proliferation and survival. This metabolic dependency can be exploited pharmacologically to sensitize FLT3-ITD-driven AMLs to chemotherapy.<i>This article is highlighted in the In This Issue feature, p. 1307</i>.