Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Department of Internal Medicine, University of Patras School of Health Sciences, Patras, Western Greece, Greece.
J Immunother Cancer. 2021 Dec;9(12). doi: 10.1136/jitc-2021-003894.
The prognosis of patients with recurrent/refractory acute myelogenous leukemia (AML) remains poor and cell-based immunotherapies hold promise to improve outcomes. Natural Killer (NK) cells can elicit an antileukemic response via a repertoire of activating receptors that bind AML surface ligands. NK-cell adoptive transfer is safe but thus far has shown limited anti-AML efficacy. Here, we aimed to overcome this limitation by engineering NK cells to express chimeric antigen receptors (CARs) to boost their anti-AML activity and interleukin (IL)-15 to enhance their persistence.
We characterized in detail NK-cell populations expressing a panel of AML (CD123)-specific CARs and/or IL-15 in vitro and in AML xenograft models.
CARs with 2B4.ζ or 4-1BB.ζ signaling domains demonstrated greater cell surface expression and endowed NK cells with improved anti-AML activity in vitro. Initial in vivo testing revealed that only 2B4.ζ Chimeric Antigen Receptor (CAR)-NK cells had improved anti-AML activity in comparison to untransduced (UTD) and 4-1BB.ζ CAR-NK cells. However, the benefit was transient due to limited CAR-NK-cell persistence. Transgenic expression of secretory interleukin (sIL)-15 in 2B4.ζ CAR and UTD NK cells improved their effector function in the setting of chronic antigen simulation in vitro. Multiparameter flow analysis after chronic antigen exposure identified the expansion of unique NK-cell subsets. 2B4.ζ/sIL-15 CAR and sIL-15 NK cells maintained an overall activated NK-cell phenotype. This was confirmed by transcriptomic analysis, which revealed a highly proliferative and activated signature in these NK-cell groups. In vivo, 2B4.ζ/sIL-15 CAR-NK cells had potent anti-AML activity in one model, while 2B4.ζ/sIL-15 CAR and sIL-15 NK cells induced lethal toxicity in a second model.
Transgenic expression of CD123-CARs and sIL-15 enabled NK cells to function in the setting of chronic antigen exposure but was associated with systemic toxicities. Thus, our study provides the impetus to explore inducible and controllable expression systems to provide cytokine signals to AML-specific CAR-NK cells before embarking on early-phase clinical testing.
复发性/难治性急性髓系白血病（AML）患者的预后仍然较差，细胞为基础的免疫疗法有望改善预后。自然杀伤（NK）细胞可以通过一系列结合 AML 表面配体的激活受体来引发抗白血病反应。NK 细胞过继转移是安全的，但迄今为止，其抗 AML 疗效有限。在这里，我们旨在通过工程改造 NK 细胞表达嵌合抗原受体（CAR）来增强其抗 AML 活性，并表达白细胞介素（IL）-15 以增强其持久性，从而克服这一限制。
我们详细描述了体外和 AML 异种移植模型中表达一系列 AML（CD123）特异性 CAR 和/或 IL-15 的 NK 细胞群体。
具有 2B4.ζ 或 4-1BB.ζ 信号结构域的 CAR 表现出更高的细胞表面表达水平，并赋予 NK 细胞在体外更好的抗 AML 活性。初步体内试验表明，与未转导（UTD）和 4-1BB.ζ CAR-NK 细胞相比，只有 2B4.ζ CAR-NK 细胞具有改善的抗 AML 活性。然而，由于 CAR-NK 细胞的持久性有限，这种益处是短暂的。在 2B4.ζ CAR 和 UTD NK 细胞中转基因表达分泌型白细胞介素（sIL）-15，可改善其在体外慢性抗原刺激下的效应功能。慢性抗原暴露后的多参数流式分析鉴定出独特的 NK 细胞亚群的扩增。2B4.ζ/sIL-15 CAR 和 sIL-15 NK 细胞保持整体激活的 NK 细胞表型。这通过转录组分析得到证实，该分析揭示了这些 NK 细胞群中高度增殖和激活的特征。在体内，2B4.ζ/sIL-15 CAR-NK 细胞在一种模型中具有强大的抗 AML 活性，而在另一种模型中，2B4.ζ/sIL-15 CAR 和 sIL-15 NK 细胞则引起致命毒性。
CD123-CAR 和 sIL-15 的转基因表达使 NK 细胞能够在慢性抗原暴露的情况下发挥作用，但与全身毒性有关。因此，我们的研究为探索诱导和可控表达系统提供了动力，以便在进行早期临床测试之前向 AML 特异性 CAR-NK 细胞提供细胞因子信号。
