Xu Ning, Tse Benjamin, Yang Lu, Tang Tiffany C Y, Haber Michelle, Micklethwaite Kenneth, Dolnikov Alla
Children's Cancer Institute, University of New South Wales, Sydney, NSW, Australia.
School of Women's and Children's Health, University of New South Wales, Sydney, NSW, Australia.
Immunotargets Ther. 2021 Apr 28;10:123-140. doi: 10.2147/ITT.S296161. eCollection 2021.
Despite the success of chimeric antigen receptor (CAR) T cells in clinical studies, a significant proportion of responding patients eventually relapsed, with the latter correlating with low CAR T cell expansion and persistence.
Using patient-derived xenograft (PDX) mouse models of CD19 B cell acute lymphoblastic leukemia (B-ALL), we show that priming leukemia-bearing mice with 5-azacytidine (AZA) enhances CAR T cell therapy. AZA given 1 day prior to CAR T cell infusion delayed leukemia growth and promoted CAR T cell expansion and effector function. Priming leukemia cells with AZA increased CAR T cell/target cell conjugation and target cell killing, promoted CAR T cell divisions and expanded IFNγ effector T cells in co-cultures with CD19 leukemia Nalm-6 and Raji cells. Transcriptome analysis revealed activation of diverse immune pathways in leukemia cells isolated from mice treated with AZA. We propose that epigenetic priming with AZA induces transcriptional changes that sensitize tumor cells to subsequent CAR T cell treatment. Among the candidate genes up-regulated by AZA is which encodes OX40L, one of the strongest T cell co-stimulatory ligands. OX40L binds OX40, the TNF receptor superfamily member highly specific for activated T cells. is heterogeneously expressed in a panel of pediatric PDXs, and high expression correlated with increased CAR T cell numbers identified in co-cultures with individual PDXs. High OX40L expression in Nalm-6 cells increased their susceptibility to CAR T cell killing while OX40L blockade reduced leukemia cell killing.
We propose that treatment with AZA activates OX40L/OX40 co-stimulatory signaling in CAR T cells. Our data suggest that the clinical use of AZA before CAR T cells could be considered.
尽管嵌合抗原受体（CAR）T细胞在临床研究中取得了成功，但仍有相当一部分有反应的患者最终复发，后者与CAR T细胞的低扩增和持久性相关。
使用CD19 B细胞急性淋巴细胞白血病（B-ALL）的患者来源异种移植（PDX）小鼠模型，我们发现用5-氮杂胞苷（AZA）预处理荷白血病小鼠可增强CAR T细胞疗法。在CAR T细胞输注前1天给予AZA可延迟白血病生长，并促进CAR T细胞扩增和效应功能。用AZA预处理白血病细胞可增加CAR T细胞/靶细胞结合及靶细胞杀伤，促进CAR T细胞分裂，并在与CD19白血病Nalm-6和Raji细胞共培养时扩增IFNγ效应T细胞。转录组分析揭示了从用AZA治疗的小鼠中分离出的白血病细胞中多种免疫途径的激活。我们提出，用AZA进行表观遗传预处理可诱导转录变化，使肿瘤细胞对随后的CAR T细胞治疗敏感。AZA上调的候选基因之一是 ，其编码OX40L，最强的T细胞共刺激配体之一。OX40L结合OX40，OX40是对活化T细胞高度特异的肿瘤坏死因子受体超家族成员。 在一组儿科PDX中异质性表达，高 表达与在与单个PDX共培养中鉴定出的CAR T细胞数量增加相关。Nalm-6细胞中高OX40L表达增加了它们对CAR T细胞杀伤的敏感性，而OX40L阻断则降低了白血病细胞杀伤。
我们提出用AZA治疗可激活CAR T细胞中的OX40L/OX40共刺激信号。我们的数据表明，可以考虑在CAR T细胞之前临床使用AZA。
