Pharmacologically Targeting DHODH-Dependent Pyrimidine Metabolism with HSA-Conjugated BRQ Suppresses Leukemogenesis

Background: Metabolic reprogramming is a hallmark of acute myeloid leukemia (AML) and provides a rich source of therapeutic vulnerabilities. Among these, de novo pyrimidine biosynthesis has emerged as an important metabolic dependency, yet its contribution to AML progression remains incompletely defined. DHODH, a rate-limiting enzyme in this pathway, represents a promising therapeutic target; however, the clinical development of DHODH inhibitors has been constrained by limited efficacy and dose-limiting toxicity. Thus, defining the mechanistic role of DHODH in AML and developing strategies to improve the therapeutic index of DHODH inhibition remain important unmet needs. Methods: The Cancer Dependency Map (DepMap) database was utilized to identify AML-essential genes that were preferentially required for AML cell survival. Gene set enrichment analysis (GSEA) was used to characterize metabolic dependencies and identify candidate targets. The functional role of DHODH was subsequently evaluated by using genetic knockout in AML cell lines and patient-derived xenograft (PDX) cells. NSGS mice were used in the "human-in-mouse" xenograft mice model. Metabolic profiling coupled with ¹³C isotope tracing was performed to define DHODH-dependent metabolic alterations, while RNA-seq and genetic rescue assays were used to investigate the mechanisms underlying DHODH-mediated leukemogenesis and ferroptosis. Pharmacologically, we evaluated the DHODH inhibitor BRQ and developed an HSA-based BRQ delivery strategy to improve therapeutic efficacy and reduce systemic toxicity. Results: Our study identified DHODH as a critical vulnerability in AML. DHODH knockout (KO) significantly suppressed AML cell growth, induced apoptosis in vitro, and markedly inhibited AML progression in vivo, supporting a crucial role of DHODH in leukemogenesis. Metabolic profiling further confirmed the dependence of AML cells on DHODH-mediated de novo pyrimidine biosynthesis for leukemic progression. RNA-seq revealed marked activation of the ferroptosis pathway following DHODH KO, with HMOX1 identified as a functionally essential target of DHODH depletion-induced ferroptosis. Pharmacologically, the DHODH inhibitor BRQ phenocopied the antileukemia effects of genetic DHODH depletion both in vitro and in vivo. Of note, we have developed an HSA-based delivery strategy aimed at improving therapeutic efficacy while reducing systemic toxicity. Targeting DHODH, particularly with HSA-conjugated BRQ, represents a promising therapeutic strategy for AML.