虽然免疫疗法彻底改变了肿瘤学领域，但治疗反应性的变化限制了这些疗法的广泛适用性。免疫细胞（特别是 CD8 T 细胞）动态的诊断成像可以实现早期患者分层，从而提高治疗效果和安全性。在这项研究中，我们报告了一种基于纳米抗体的免疫示踪剂的开发，用于人类 CD8 T 细胞动力学的非侵入性 SPECT 和 PET 成像。针对人类 CD8β 的纳米抗体是通过美洲驼免疫和随后的生物淘选产生的。对先导抗人 CD8β 纳米抗体的结合、特异性、稳定性和毒性进行了表征。铅纳米抗体标记有锝-99m、镓-68和铜-64，用于通过 SPECT/CT 或 PET/CT 对人 T 细胞淋巴瘤和人 CD8 转基因小鼠和非人灵长类动物中的 CD8 T 细胞进行无创成像。对 MC38 荷瘤小鼠中的 CD8 T 细胞进行重复成像，可实现 CD8 T 细胞动态的可视化。基于纳米抗体的免疫示踪剂显示出与人类 CD8 的高亲和力和特异性结合，而不会激活不必要的免疫。通过 SPECT 和 PET 成像，在幼稚小鼠和荷瘤小鼠以及幼稚非人灵长类动物中以高灵敏度非侵入性地观察到 CD8 T 细胞。与之前的人类 CD8 靶向免疫示踪剂相比，基于纳米抗体的免疫示踪剂显示出对 CD8 T 细胞的更高特异性和/或更快的体内药代动力学，使我们能够在早期时间点跟踪人类 CD8 T 细胞动态。更具体的人类 CD8 T 细胞靶向免疫示踪剂，允许通过人类 CD8 T 细胞动态的非侵入性成像来跟踪免疫治疗反应。© 2024。作者。

While immunotherapy has revolutionized the oncology field, variations in therapy responsiveness limit the broad applicability of these therapies. Diagnostic imaging of immune cell, and specifically CD8+ T cell, dynamics could allow early patient stratification and result in improved therapy efficacy and safety. In this study, we report the development of a nanobody-based immunotracer for non-invasive SPECT and PET imaging of human CD8+ T-cell dynamics.Nanobodies targeting human CD8β were generated by llama immunizations and subsequent biopanning. The lead anti-human CD8β nanobody was characterized on binding, specificity, stability and toxicity. The lead nanobody was labeled with technetium-99m, gallium-68 and copper-64 for non-invasive imaging of human T-cell lymphomas and CD8+ T cells in human CD8 transgenic mice and non-human primates by SPECT/CT or PET/CT. Repeated imaging of CD8+ T cells in MC38 tumor-bearing mice allowed visualization of CD8+ T-cell dynamics.The nanobody-based immunotracer showed high affinity and specific binding to human CD8 without unwanted immune activation. CD8+ T cells were non-invasively visualized by SPECT and PET imaging in naïve and tumor-bearing mice and in naïve non-human primates with high sensitivity. The nanobody-based immunotracer showed enhanced specificity for CD8+ T cells and/or faster in vivo pharmacokinetics compared to previous human CD8-targeting immunotracers, allowing us to follow human CD8+ T-cell dynamics already at early timepoints.This study describes the development of a more specific human CD8+ T-cell-targeting immunotracer, allowing follow-up of immunotherapy responses by non-invasive imaging of human CD8+ T-cell dynamics.© 2024. The Author(s).