Chimeric antigen receptor (CAR) T cell therapy is effective in lymphoid malignancies, but there has been limited data in myeloid cancers. Here, we start with a CD27-based CAR to target CD70 (“native”) in acute myeloid leukemia (AML), and we find modest efficacy in vivo, consistent with prior reports. We then use orthogonal approaches to increase binding on both the tumor and CAR-T cell sides of the immune synapse: a pharmacologic approach (azacitidine) to increase antigen density of CD70 in myeloid tumors, and an engineering approach to stabilize binding of the CAR to CD70. To accomplish the latter, we design a panel of hinge-modified regions to mitigate cleavage of the extracellular portion of CD27. Our CD8 hinge and transmembrane-modified CD70 CAR-T cells are less prone to cleavage, have enhanced binding avidity, and increased expansion, leading to more potent in vivo activity. This enhanced CD70-targeted CAR is a promising candidate for further clinical development.

嵌合抗原受体 (CAR) T 细胞疗法对淋巴恶性肿瘤有效，但在骨髓癌方面的数据有限。在这里，我们从基于 CD27 的 CAR 开始，在急性髓系白血病 (AML) 中靶向 CD70（“天然”），我们发现体内疗效中等，与之前的报道一致。然后，我们使用正交方法来增加免疫突触的肿瘤和 CAR-T 细胞侧的结合：一种药理学方法（阿扎胞苷）来增加骨髓肿瘤中 CD70 的抗原密度，以及一种工程方法来稳定 CAR 与CD70。为了实现后者，我们设计了一组铰链修饰区域来减轻 CD27 细胞外部分的裂解。我们的 CD8 铰链和跨膜修饰的 CD70 CAR-T 细胞不易裂解，具有增强的结合亲合力和增加的扩增，从而导致更有效的体内活性。这种增强型 CD70 靶向 CAR 是进一步临床开发的有希望的候选者。