急性巨核细胞白血病（AMKL）是一种罕见的、发育限制性和高度致命的儿童早期癌症。患者样本的稀少和低细胞密度（因骨髓纤维化）阻碍了细胞和基因型特异性治疗的发现。AMKL在三分之二的病例中由相互排斥的融合致癌基因驱动，其中CBFA2T3::GLIS2（CG2）和NUP98融合（NUP98r）代表了最高致死亚群。我们建立了从CD34+脐血中来源的CG2模型（n=6），该模型能够支持串行移植并重现人类白血病的免疫表型、白血病发起细胞频率、共突变谱和基因表达特征，其中明显上调了促存活因子BCL2。细胞膜蛋白组学分析突出显示，与CD34+细胞相比，CG2表面标记物更倾向于在白血病细胞上表达（如NCAM1、CD151）。单个细胞分析证实了AMKL巨核红系祖细胞空间的分化阻滞。虽然CG2细胞对BCL2基因敲降或选择性药物抑制剂Venetoclax相对抵抗，但对针对巨核核红系细胞促存活因子BCL-XL（BCL2L1）的策略比较容易受到攻击，包括使用体外和体内治疗的BCL2/BCL-XL/BCL-W抑制剂Navitoclax和DT2216，DT2216是一种选择性BCL-XL PRO（蛋白酶靶向嵌合体）降解剂，用于限制患者血小板减少。NUP98r AMKL对BCL-XL抑制也敏感，但NUP98r单核细胞白血病则不敏感，这指向了一种特定于细胞系的依赖性。Navitoclax或DT2216与低剂量细胞阿糖胞苷联合治疗进一步降低了小鼠的白血病负担。本研究扩展了人类AMKL模型的细胞和分子多样性，并揭示了CG2和NUP98r AMKL中BCL-XL作为一种治疗性易感性。版权所有©2023年美国血液学学会。

Acute megakaryoblastic leukemia (AMKL) is a rare, developmentally restricted and highly lethal cancer of early childhood. The paucity and hypocellularity (due to myelofibrosis) of primary patient samples hamper the discovery of cell- and genotype-specific treatments. AMKL is driven by mutually exclusive chimeric fusion oncogenes in two thirds of cases, with CBFA2T3::GLIS2 (CG2) and NUP98 fusions (NUP98r) representing the highest fatality subgroups. We established CD34+ cord blood-derived CG2 models (n=6) that sustain serial transplantation and recapitulate human leukemia regarding immunophenotype, leukemia initiating cell frequencies, co-mutational landscape and gene expression signature with distinct upregulation of the pro-survival factor BCL2. Cell membrane proteomic analyses highlighted CG2 surface markers preferentially expressed on leukemic cells compared to CD34+ cells (e.g. NCAM1, CD151). AMKL differentiation block in the mega-erythroid progenitor space was confirmed by single cell profiling. While CG2 cells were rather resistant to BCL2 genetic knockdown or selective pharmacological inhibition with Venetoclax, they were vulnerable to strategies that target the megakaryocytic pro-survival factor BCL-XL (BCL2L1), including in vitro and in vivo treatment with BCL2/BCL-XL/BCL-W inhibitor Navitoclax and DT2216, a selective BCL-XL PROTAC (proteolysis-targeting chimera) degrader developed to limit thrombocytopenia in patients. NUP98r AMKL were also sensitive to BCL-XL inhibition, but not the NUP98r monocytic leukemia, pointing to a lineage-specific dependency. Navitoclax or DT2216 treatment in combination with low dose cytarabine further reduced leukemic burden in mice. This work extends the cellular and molecular diversity set of human AMKL models and uncovers BCL-XL as a therapeutic vulnerability in CG2 and NUP98r AMKL.Copyright © 2023 American Society of Hematology.