Therapeutic Targeting of Mesothelin with Chimeric Antigen Receptor T Cells in Acute Myeloid Leukemia.
Therapeutic Targeting of Mesothelin with Chimeric Antigen Receptor T Cells in Acute Myeloid Leukemia.
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DOI：
10.1158/1078-0432.ccr-21-1546
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发表时间：
2021-10-15
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我们先前鉴定了间皮素（MSLN）在急性髓性白血病（AML）的显著部分中高度表达，但在正常造血中完全沉默，从而为避免造血毒性的免疫靶向提供了有希望的抗原。鉴于经遗传修饰以表达嵌合抗原受体（CAR）的T细胞在根除复发性/难治性急性淋巴细胞白血病方面是有效的，我们开发了MSLN定向的CAR T细胞用于AML的临床前评估。来自靶向MSLN的SS 1 P免疫毒素的可变轻链（VL）和重链（VH）序列用于构建含有41-BB共刺激和CD 3 ζ刺激结构域的标准CAR的单链可变片段。在体外和体内针对表达各种水平MSLN的AML细胞系和患者样品评价MSLN CAR T细胞的临床前功效。我们证明MSLN在AML原始细胞和富含白血病干细胞的CD 34 + CD 38 −亚群的细胞表面表达，但在正常造血干细胞和祖细胞（HSPC）上不表达。我们进一步确定了MSLN CAR T细胞在细胞系和患者来源的异种移植模型中消除MSLN阳性AML细胞方面非常有效。重要的是，MSLN CAR T细胞可以靶向和根除CD 34 + CD 38 −细胞，而不影响正常HSPC的活力。最后，我们表明CAR T细胞的功能可以通过抑制促进MSLN脱落的ADAM 17金属蛋白酶来改善。这些发现表明MSLN是AML中CAR T细胞疗法的可行靶标，并且抑制MSLN脱落是改善CAR T细胞功效的有希望的方法。
We previously identified mesothelin (MSLN) as highly expressed in a significant fraction of acute myeloid leukemia (AML) but entirely silent in normal hematopoiesis, providing a promising antigen for immunotherapeutic targeting that avoids hematopoietic toxicity. Given that T cells genetically modified to express chimeric antigen receptors (CAR) are effective at eradicating relapsed/refractory acute lymphocytic leukemia, we developed MSLN-directed CAR T cells for preclinical evaluation in AML. The variable light (VL) and heavy (VH) sequences from the MSLN-targeting SS1P immunotoxin were used to construct the single-chain variable fragment of the standard CAR containing 41-BB costimulatory and CD3Zeta stimulatory domains. The preclinical efficacy of MSLN CAR T cells was evaluated against AML cell lines and patient samples expressing various levels of MSLN in vitro and in vivo. We demonstrate that MSLN is expressed on the cell surface of AML blasts and leukemic stem cell–enriched CD34+CD38− subset, but not on normal hematopoietic stem and progenitor cells (HSPC). We further establish that MSLN CAR T cells are highly effective in eliminating MSLN-positive AML cells in cell line– and patient-derived xenograft models. Importantly, MSLN CAR T cells can target and eradicate CD34+CD38− cells without impacting the viability of normal HSPCs. Finally, we show that CAR T-cell functionality can be improved by inhibition of the ADAM17 metalloprotease that promotes shedding of MSLN. These findings demonstrate that MSLN is a viable target for CAR T-cell therapy in AML and that inhibiting MSLN shedding is a promising approach to improve CAR T-cell efficacy.