IDH1-mutant preleukemic hematopoietic stem cells can be eliminated by oxphos inhibition

Rare preleukemic hematopoietic stem cells (pHSCs) harboring only the initiating mutations can be detected at the time of AML diagnosis. pHSCs are likely the origin of leukemia and a potential reservoir for relapse but remain challenging to eradicate. Using primary human samples and gene-editing to model isocitrate dehydrogenase 1 (IDH1) mutant pHSCs, we show biological, transcriptional, and metabolic differences between pHSCs and healthy hematopoietic stem cells (HSCs). We confirm that IDH1 mutations are present in patients with clonal cytopenia of undetermined significance, but not in individuals with clonal hematopoiesis of indeterminate potential, suggesting an inherent defect to fully reconstitute hematopoiesis. Despite giving rise to multilineage engraftment, IDH1-mutant pHSCs exhibited reduced proliferation with a block in differentiation, downregulation of MHC Class II genes and reprogramming of oxphos metabolism. Critically, IDH1-mutant pHSCs showed reduced metabolic activity distinct from normal HSCs and inhibition of oxphos resulted in complete eradication of IDH1-mutant pHSCs but not IDH2-mutant pHSCs or wildtype HSCs. Our results indicate that IDH1-mutant preleukemic clones can be targeted with complex I inhibitors to prevent development and relapse of leukemia. Human cord blood derived HSPCs from four donors were genetically engineered to expressed wildtype or mutant IDH1 or IDH2 and an AAVS1 GFP only control and subjected to RNA sequencing.

仅携带起始突变的稀有白血病前期造血干细胞（preleukemic hematopoietic stem cells, pHSCs）可在急性髓系白血病（Acute Myeloid Leukemia, AML）确诊阶段被检出。pHSCs极有可能是白血病的起源细胞，同时也是白血病复发的潜在储备库，但目前仍难以被彻底清除。本研究借助原代人类样本与基因编辑技术，构建异柠檬酸脱氢酶1（isocitrate dehydrogenase 1, IDH1）突变型pHSCs模型，揭示了pHSCs与健康造血干细胞（hematopoietic stem cells, HSCs）在生物学特征、转录组及代谢层面的显著差异。本研究证实，IDH1突变可见于意义未明的克隆性血细胞减少症（clonal cytopenia of undetermined significance, CCUS）患者，但未在意义未定的克隆性造血（clonal hematopoiesis of indeterminate potential, CHIP）人群中检测到该突变，这提示IDH1突变型pHSCs存在造血功能完全重建的固有缺陷。尽管IDH1突变型pHSCs可实现多系造血植入，但其增殖能力减弱且分化进程受阻，同时伴随主要组织相容性复合体II类（Major Histocompatibility Complex Class II, MHC II）基因下调，以及氧化磷酸化（oxidative phosphorylation, oxphos）代谢重编程。尤为关键的是，与正常HSCs相比，IDH1突变型pHSCs的代谢活性显著降低；而氧化磷酸化抑制剂可彻底清除IDH1突变型pHSCs，但对异柠檬酸脱氢酶2（isocitrate dehydrogenase 2, IDH2）突变型pHSCs及野生型HSCs无此效果。本研究结果显示，可通过复合体I（complex I）抑制剂靶向IDH1突变型白血病前期克隆，从而阻断白血病的发生与复发进程。本研究对4名供者的人脐带血来源造血干祖细胞（hematopoietic stem and progenitor cells, HSPCs）进行基因工程改造，使其分别表达野生型或突变型IDH1、IDH2，同时设置仅通过腺苷相关病毒整合位点1（adeno-associated virus integration site 1, AAVS1）位点插入GFP的空白对照组，随后对所有样本开展RNA测序（RNA sequencing）。