复发或难治性T细胞急性淋巴细胞白血病（T-ALL）患者预后不良，治疗选择有限。为了确定新的治疗靶点，我们利用依赖地图计划的数据，确定了DHODH（二氢乳酸酶）作为T-ALL中一种重要的代谢依赖性之一。DHODH催化新的嘌呤核苷酸合成的第四步。小分子抑制剂抑制DHODH会迅速耗尽细胞内嘌呤核苷酸储备，使细胞依赖于外源性救援。在救援不足的情况下，细胞内缺乏嘌呤核苷酸导致DNA和RNA合成受到抑制，细胞周期停滞，最终导致细胞死亡。T淋巴母细胞在DHODH抑制后对嘌呤缺乏表现出特异性和敏感性。我们在三个小鼠T-ALL模型中通过体外和体内实验证实了这种敏感性。我们发现，在DHODH抑制治疗时，某些T-ALL亚群似乎更加依赖氧化磷酸化。通过一系列代谢分析，我们展示了在嘌呤缺乏的环境中，白血病细胞的线粒体膜电位发生变化，并可能更高度依赖备用燃料来源。还研究了年轻小鼠正常T细胞发育的影响，表明DHODH抑制对发育中的胸腺没有永久损伤。这些变化表明了一种新的代谢脆弱性，使这些细胞与正常的T细胞和其他正常造血细胞区别开来，并提供了可利用的治疗机会。目前，临床级别的DHODH抑制剂已在人体临床试验中，显示了迅速推进该研究进入临床的潜力。© 2023年美国血液学会。

Patients with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL) have a poor prognosis with few therapeutic options. With the goal of identifying novel therapeutic targets, we used data from the Dependency Map project to identify DHODH (dihydroorotate dehydrogenase) as one of the top metabolic dependencies in T-ALL. DHODH catalyzes the fourth step of de novo pyrimidine nucleotide synthesis. Small molecule inhibition of DHODH rapidly leads to the depletion of intracellular pyrimidine pools and forces cells to rely on extracellular salvage. In the absence of sufficient salvage, this intracellular nucleotide starvation results in the inhibition of DNA and RNA synthesis, cell cycle arrest, and ultimately death. T lymphoblasts appear to be specifically and exquisitely sensitive to nucleotide starvation following DHODHi. We have confirmed this sensitivity in vitro as well as in vivo in three murine models of T ALL. We identified that certain subsets of T-ALL seem to have an increased reliance on oxidative phosphorylation when treated with DHODHi. Through a series of metabolic assays, we show that leukemia cells, in the setting of nucleotide starvation, have changes in their mitochondrial membrane potential and may be more highly dependent on alternative fuel sources. The effect on normal T cell development in young mice was also examined to show that DHODH inhibition does not permanent damage the developing thymus. These changes suggest a new metabolic vulnerability that may distinguish these cells from normal T-cells and other normal hematopoietic cells and offer an exploitable therapeutic opportunity. The availability of clinical-grade DHODH inhibitors currently in human clinical trials speaks to the potential for rapidly advancing this work into the clinic.Copyright © 2023 American Society of Hematology.