Department of Radiology, Houston Methodist Research Institute, Houston, Texas, USA.
Department of Radiology, Weill Cornell Medicine, New York, New York, USA.
JCI Insight. 2024 Nov 22;9(22):e186268. doi: 10.1172/jci.insight.186268.
The application of chimeric antigen receptor (CAR) T cell therapy in solid tumors is hindered by life-threatening toxicities resulting from on-target, off-tumor killing of nonmalignant cells that express low levels of the target antigen. Mesothelin (MSLN) has been identified as a target antigen for CAR T cell treatment of mesothelioma, lung, ovarian, and other cancers because of its high expression on tumor cells and limited expression on mesothelial cells. However, fatal off-tumor toxicity of high-affinity MSLN-targeting CAR T cells has been reported in multiple clinical trials. In this study, we constructed CARs using mutant variants of a single-domain nanobody that bind both human and mouse MSLN with a wide range of affinities and examined tumor responses and their toxicities from on-target, off-tumor interactions in mouse models. CAR T cells with low nanomolar affinity (equilibrium dissociation constant, KD) exhibited profound systemic expansion with no apparent infiltration into the tumor. With a gradual reduction of CAR affinity toward the micromolar KD, the expansion of CAR T cells became more restricted to tumors. Our preclinical studies demonstrated that high-affinity MSLN CARs were associated with fatal on-target, off-tumor toxicity and that affinity-tuned CARs rendered T cells more selective for MSLN-high tumors.
嵌合抗原受体 (CAR) T 细胞疗法在实体瘤中的应用受到限制，因为其对低水平表达靶抗原的非恶性细胞的靶向脱靶杀伤会导致危及生命的毒性。间皮素 (MSLN) 因其在肿瘤细胞上的高表达和间皮细胞上的有限表达而被确定为 CAR T 细胞治疗间皮瘤、肺癌、卵巢癌和其他癌症的靶抗原。然而，在多项临床试验中已经报道了高亲和力 MSLN 靶向 CAR T 细胞的致命脱靶毒性。在这项研究中，我们使用与人和鼠 MSLN 具有广泛亲和力的单域纳米体的突变变体构建了 CAR，并在小鼠模型中检查了针对靶标、脱靶相互作用的肿瘤反应及其毒性。具有低纳摩尔亲和力 (平衡解离常数，KD) 的 CAR T 细胞表现出明显的全身性扩增，而没有明显浸润到肿瘤中。随着 CAR 亲和力逐渐降低至微摩尔 KD，CAR T 细胞的扩增变得更加局限于肿瘤。我们的临床前研究表明，高亲和力 MSLN CAR 与致命的靶向脱靶毒性相关，而亲和力调节的 CAR 使 T 细胞对 MSLN-高肿瘤更具选择性。
