PROJECT SUMMARY/ABSTRACT Acute myeloid leukemia (AML) is a genetically complex and heterogeneous set of diseases characterized by a diverse set of mutations. Although many patients initially respond to treatment, many end up relapsing. Over the last decade, an appreciation of the genetic diversity and clonal hierarchy in AML has opened the door to novel therapeutic targets and therapeutic approaches to specific AML subtypes. Moreover, AML has been found to bear unique metabolic features with therapeutic implications. Most importantly, mutations in the enzymes isocitrate dehydrogenase (IDH1/2) have led to clinically approved drugs. However, many patients become resistant to this therapy as well, further underscoring the need for new strategies to target dysregulated metabolism in leukemia. Through the development of novel microcoil platforms to explore leukemia metabolism with HP MR (Jeong et al. Science Advances 2017) we have identified a new metabolic vulnerability in the glycolytic metabolism of leukemia (Jeong et al. Cell Metabolism 2021). This reliance on glycolytic metabolism alters not only glucose flux to lactate, but also one-carbon flux through the serine pathway, which facilitates the metabolism of glutamine. Moreover, we found that genetically targeting or pharmacologically inhibiting the enzyme that mediates flux through this pathway (PHGDH) capitalizes on a new vulnerability in these cells. Importantly, this targeting does not affect normal hematopoietic cell growth. Thus, building upon extensive collaboration between our labs and ample preliminary data, we aim to employ innovative approaches to study metabolism (Keshari Lab), including by developing non-invasive probes to measure changes in glycolysis and oxidative stress with hyperpolarized magnetic resonance imaging. This metabolism will be characterized in well- defined models of AML (Kharas Lab), with both genetic and pharmacological modulation, in order to develop a strategy to assess leukemia-stem-cell-driven AML metabolism and the inhibition of serine metabolism. Altogether, these studies will result in new mechanistic insights and novel cancer therapies.