利用针对人类CD8β的纳米抗体放射性示踪剂的CD8+ T细胞动态的特异性成像

Specific imaging of CD8 + T-Cell dynamics with a nanobody radiotracer against human CD8β

EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING

影响因子:7.6

分区:医学1区 Top / 核医学1区

发表日期:2024 Dec

作者: Timo W M De Groof, Yoline Lauwers, Tessa De Pauw, Mohit Saxena, Cécile Vincke, Jolien Van Craenenbroeck, Catherine Chapon, Roger Le Grand, Geert Raes, Thibaut Naninck, Jo A Van Ginderachter, Nick Devoogdt

DOI: 10.1007/s00259-024-06896-3

摘要

免疫疗法已彻底改变了肿瘤学领域，但疗效的差异限制了这些疗法的广泛应用。免疫细胞，特别是CD8+ T细胞的动态成像，可能实现早期患者分层，从而提高治疗的有效性和安全性。在本研究中，我们报道了一种基于纳米抗体的免疫示踪剂，用于非侵入性SPECT和PET成像人类CD8+ T细胞的动态。通过驼羚免疫和随后的生物筛选，生成了靶向人类CD8β的纳米抗体。对候选抗体的结合、特异性、稳定性和毒性进行了表征。该纳米抗体用含锝-99m、镓-68和铜-64的放射性核素标记，用于在人体CD8转基因小鼠和非人灵长类动物中通过SPECT/CT或PET/CT进行人类T细胞淋巴瘤和CD8+ T细胞的非侵入性成像。在MC38肿瘤模型小鼠中反复成像，能观察到CD8+ T细胞的动态变化。结果显示，该纳米抗体示踪剂具有高亲和力和特异性，无不良免疫激活，在未感染和肿瘤模型的小鼠以及未感染的非人灵长类动物中，均能高灵敏度地实现人类CD8+ T细胞的非侵入性成像。与之前的抗人类CD8免疫示踪剂相比，该纳米抗体示踪剂显示出增强的特异性和/或更快的体内药代动力学，能在早期时间点追踪人类CD8+ T细胞的动态。本文描述了一种更具特异性的抗人类CD8+ T细胞的免疫示踪剂，有助于通过非侵入性成像跟踪免疫疗法的响应。

Abstract

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.