Obstetrics and Gynecology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
J Immunother Cancer. 2022 Dec;10(12). doi: 10.1136/jitc-2022-004877.
CD103, an integrin specifically expressed on the surface of cancer-reactive T cells, is significantly increased during successful immunotherapy across human malignancies. In this study, we describe the generation and zirconium-89 (Zr) radiolabeling of monoclonal antibody (mAb) clones that specifically recognize human CD103 for non-invasive immune positron-emission tomography (PET) imaging of T cell infiltration as potential biomarker for effective anticancer immune responses.
First, to determine the feasibility of anti-CD103 immuno-PET to visualize CD103-positive cells at physiologically and clinically relevant target densities, we developed an Zr-anti-murine CD103 PET tracer. Healthy, non-tumor bearing C57BL/6 mice underwent serial PET imaging after intravenous injection, followed by ex vivo biodistribution. Tracer specificity and macroscopic tissue distribution were studied using autoradiography combined with CD103 immunohistochemistry. Next, we generated and screened six unique mAbs that specifically target human CD103 positive cells. Optimal candidates were selected for Zr-anti-human CD103 PET development. Nude mice (BALB/cOlaHsd-Foxn1nu) with established CD103 expressing Chinese hamster ovary (CHO) or CHO wild-type xenografts were injected with Zr-anti-human CD103 mAbs and underwent serial PET imaging, followed by ex vivo biodistribution.
Zr-anti-murine CD103 PET imaging identified CD103-positive tissues at clinically relevant target densities. For human anti-human CD103 PET development two clones were selected based on strong binding to the CD103 CD8 T cell subpopulation in ovarian cancer tumor digests, non-overlapping binding epitopes and differential CD103 blocking properties. In vivo, both Zr-anti-human CD103 tracers showed high target-to-background ratios, high target site selectivity and a high sensitivity in human CD103 positive xenografts.
CD103 immuno-PET tracers visualize CD103 T cells at relevant densities and are suitable for future non-invasive assessment of cancer reactive T cell infiltration.
CD103 是一种整合素，特异性表达于肿瘤反应性 T 细胞表面，在多种人类恶性肿瘤的成功免疫治疗中显著增加。本研究描述了单克隆抗体 (mAb) 克隆的产生和锆-89（Zr）放射性标记，这些 mAb 特异性识别人 CD103，可用于 T 细胞浸润的非侵入性免疫正电子发射断层扫描 (PET) 成像，作为有效抗癌免疫反应的潜在生物标志物。
首先，为了确定抗 CD103 免疫 PET 用于可视化生理和临床相关靶密度下 CD103 阳性细胞的可行性，我们开发了一种 Zr-抗鼠 CD103 PET 示踪剂。健康、无肿瘤的 C57BL/6 小鼠静脉注射后进行连续 PET 成像，然后进行离体生物分布研究。通过放射性自显影结合 CD103 免疫组织化学研究示踪剂的特异性和宏观组织分布。接下来，我们生成并筛选了六种特异性靶向人 CD103 阳性细胞的独特 mAb。选择最佳候选物用于 Zr-抗人 CD103 PET 的开发。用建立的表达 CD103 的中国仓鼠卵巢 (CHO) 或 CHO 野生型异种移植瘤的裸鼠 (BALB/cOlaHsd-Foxn1nu) 注射 Zr-抗人 CD103 mAb 并进行连续 PET 成像，然后进行离体生物分布。
Zr-抗鼠 CD103 PET 成像可在临床相关靶密度下识别 CD103 阳性组织。为了开发人抗人 CD103 PET，我们根据在卵巢癌肿瘤消化物中与 CD103 CD8 T 细胞亚群的强结合、非重叠结合表位和不同的 CD103 阻断特性，从两种克隆中选择了两种克隆。在体内，两种 Zr-抗人 CD103 示踪剂在人 CD103 阳性异种移植瘤中均显示出高靶背比、高靶位选择性和高灵敏度。
CD103 免疫 PET 示踪剂可在相关密度下可视化 CD103 T 细胞，适用于未来对肿瘤反应性 T 细胞浸润的非侵入性评估。
