For the past several decades, chimeric antigen receptor T-cell therapies have shown promise in the treatment of cancers. These treatments would greatly benefit from companion imaging biomarkers to follow the trafficking of T cells in vivo. Methods: Using synthetic biology, we engineered T cells with a chimeric receptor synthetic intramembrane proteolysis receptor (SNIPR) that induces overexpression of an exogenous reporter gene cassette on recognition of specific tumor markers. We then applied a SNIPR-based PET reporter system to 2 cancer-relevant antigens, human epidermal growth factor receptor 2 (HER2) and epidermal growth factor receptor variant III (EGFRvIII), commonly expressed in breast and glial tumors, respectively. Results: Antigen-specific reporter induction of the SNIPR PET T cells was confirmed in vitro using green fluorescent protein fluorescence, luciferase luminescence, and the HSV-TK PET reporter with 9-(4-¹⁸F-fluoro-3-[hydroxymethyl]butyl)guanine ([¹⁸F]FHBG). T cells associated with their target antigens were successfully imaged using PET in dual-xenograft HER2+/HER2– and EGFRvIII+/EGFRvIII– animal models, with more than 10-fold higher [¹⁸F]FHBG signals seen in antigen-expressing tumors versus the corresponding controls. Conclusion: The main innovation found in this work was PET detection of T cells via specific antigen-induced signals, in contrast to reporter systems relying on constitutive gene expression.

在过去的几十年里，嵌合抗原受体 T 细胞疗法在治疗癌症方面显示出了希望。这些治疗将极大地受益于伴随成像生物标志物来跟踪 T 细胞在体内的运输。方法：利用合成生物学，我们用嵌合受体合成膜内蛋白水解受体（SNIPR）改造了 T 细胞，该受体在识别特定肿瘤标志物时诱导外源报告基因盒过度表达。然后，我们将基于 SNIPR 的 PET 报告系统应用于 2 种癌症相关抗原，即人表皮生长因子受体 2 (HER2) 和表皮生长因子受体变体 III (EGFRvIII)，它们分别通常在乳腺癌和神经胶质瘤中表达。结果：使用绿色荧光蛋白荧光、荧光素酶发光和具有 9-(4- ¹⁸ F-氟-3-[羟甲基]丁基) 的HSV-TK PET 报告基因在体外证实了 SNIPR PET T 细胞的抗原特异性报告基因诱导）鸟嘌呤（[ ¹⁸ F]FHBG）。在双异种移植 HER2+/HER2– 和 EGFRvIII+/EGFRvIII– 动物模型中，使用 PET 成功对与其靶抗原相关的 T 细胞进行成像，与相应的抗原表达肿瘤相比，在表达抗原的肿瘤中观察到的[ ¹⁸ F]FHBG 信号高出 10 倍以上控制。结论：这项工作的主要创新是通过特异性抗原诱导信号对 T 细胞进行 PET 检测，这与依赖组成型基因表达的报告系统不同。