In this study, we show the high frequency of spontaneous γδ T-cell leukemia (T-ALL) occurrence in mice with biallelic deletion of enhancer of zeste homolog 2 (Ezh2). Tumor cells show little residual H3K27 trimethylation marks compared with controls. EZH2 is a component of the PRC2 Polycomb group protein complex, which is associated with DNA methyltransferases. Using next-generation sequencing, we identify alteration in gene expression levels of EZH2 and acquired mutations in PRC2-associated genes (DNMT3A and JARID2) in human adult T-ALL. Together, these studies document that deregulation of EZH2 and associated genes leads to the development of mouse, and likely human, T-ALL.

Acute myeloid leukemia (AML) is associated with poor clinical outcome and the development of more effective therapies is urgently needed. G protein-coupled receptors (GPCRs) represent attractive therapeutic targets, accounting for approximately 30% of all targets of marketed drugs. Using next-generation sequencing, we studied the expression of 772 GPCRs in 148 genetically diverse AML specimens, normal blood and bone marrow cell populations as well as cord blood-derived CD34-positive cells. Among these receptors, 30 are overexpressed and 19 are downregulated in AML samples compared with normal CD34-positive cells. Upregulated GPCRs are enriched in chemokine (CCR1, CXCR4, CCR2, CX3CR1, CCR7 and CCRL2), adhesion (CD97, EMR1, EMR2 and GPR114) and purine (including P2RY2 and P2RY13) receptor subfamilies. The downregulated receptors include adhesion GPCRs, such as LPHN1, GPR125, GPR56, CELSR3 and GPR126, protease-activated receptors (F2R and F2RL1) and the Frizzled family receptors SMO and FZD6. Interestingly, specific deregulation was observed in genetically distinct subgroups of AML, thereby identifying different potential therapeutic targets in these frequent AML subgroups.

Current chemotherapies for T cell acute lymphoblastic leukemia (T-ALL) efficiently reduce tumor mass. Nonetheless, disease relapse attributed to survival of preleukemic stem cells (pre-LSCs) is associated with poor prognosis. Herein, we provide direct evidence that pre-LSCs are much less chemosensitive to existing chemotherapy drugs than leukemic blasts because of a distinctive lower proliferative state. Improving therapies for T-ALL requires the development of strategies to target pre-LSCs that are absolutely dependent on their microenvironment. Therefore, we designed a robust protocol for high-throughput screening of compounds that target primary pre-LSCs maintained in a niche-like environment, on stromal cells that were engineered for optimal NOTCH1 activation. The multiparametric readout takes into account the intrinsic complexity of primary cells in order to specifically monitor pre-LSCs, which were induced here by the SCL/TAL1 and LMO1 oncogenes. We screened a targeted library of compounds and determined that the estrogen derivative 2-methoxyestradiol (2-ME2) disrupted both cell-autonomous and non–cell-autonomous pathways. Specifically, 2-ME2 abrogated pre-LSC viability and self-renewal activity in vivo by inhibiting translation of MYC, a downstream effector of NOTCH1, and preventing SCL/TAL1 activity. In contrast, normal hematopoietic stem/progenitor cells remained functional. These results illustrate how recapitulating tissue-like properties of primary cells in high-throughput screening is a promising avenue for innovation in cancer chemotherapy.

In acute myeloid leukemia (AML), risk stratification based on cytogenetics and mutation profiling is essential but remains insufficient to select the optimal therapy. Accurate biomarkers are needed to improve prognostic assessment. We analyzed RNA sequencing and survival data of 430 AML patients and identified HMGA2 as a novel prognostic marker. We validated a quantitative PCR test to study the association of HMGA2 expression with clinical outcomes in 358 AML samples. In this training cohort, HMGA2 was highly expressed in 22.3% of AML, mostly in patients with intermediate or adverse cytogenetics. High expression levels of HMGA2 (H + ) were associated with a lower frequency of complete remission (58.8% vs 83.4%, P < 0.001), worse 3-year overall survival (OS, 13.2% vs 43.5%, P < 0.001) and relapse-free survival (RFS, 10.8% vs 44.2%, P < 0.001). A positive HMGA2 test also identified a subgroup of patients unresponsive to standard treatments. Multivariable analyses showed that H + was independently associated with significantly worse OS and RFS, including in the intermediate cytogenetic risk category. These associations were confirmed in a validation cohort of 260 patient samples from the UK NCRI AML17 trial. The HMGA2 test could be implemented in clinical trials developing novel therapeutic strategies for high-risk AML.

In a phenotypical screen of 56 acute myeloid leukemia (AML) patient samples and using a library of 10,000 compounds, we identified a hit with increased sensitivity toward SF3B1 -mutated and adverse risk AMLs. Through structure-activity relationship studies, this hit was optimized into a potent, specific, and nongenotoxic molecule called UM4118. We demonstrated that UM4118 acts as a copper ionophore that initiates a mitochondrial-based noncanonical form of cell death known as cuproptosis. CRISPR-Cas9 loss-of-function screen further revealed that iron-sulfur cluster (ISC) deficiency enhances copper-mediated cell death. Specifically, we found that loss of the mitochondrial ISC transporter ABCB7 is synthetic lethal to UM4118. ABCB7 is misspliced and down-regulated in SF3B1 -mutated leukemia, creating a vulnerability to copper ionophores. Accordingly, ABCB7 overexpression partially rescued SF3B1 -mutated cells to copper overload. Together, our work provides mechanistic insights that link ISC deficiency to cuproptosis, as exemplified by the high sensitivity of SF3B1 -mutated AMLs. We thus propose SF3B1 mutations as a biomarker for future copper ionophore–based therapies.