背景:Adnectin是衍生自人纤连蛋白(10Fn3)的第10型III结构域的蛋白质家族,具有高亲和力靶向能力。来自抗程序性死亡配体-1(PD-L1)Adnectin的正电子发射断层扫描(PET)探针,包括18F和68Ga标记的BMS-986192,最近开发用于预测患者对免疫检查点阻断的反应。68Ga标记的BMS-986192,特别是,由于68Ga的更广泛的可用性,对于欠发达地区是一个有吸引力的探针。然而,68Ga标记的BMS-986192的药代动力学和生物相容性仍然未知,尤其是在非人灵长类动物中,阻碍其进一步的临床翻译。
方法:我们使用1,4,7-三氮杂环壬烷开发了68Ga标记的BMS-986192的变体,1-戊二酸-4,7-乙酸(NODAGA)作为放射性核素螯合剂。由此产生的探针,使用接种有野生型B16F10和用人PD-L1(hPD-L1-B16F10)转导的B16F10的双侧小鼠肿瘤模型,在靶向特异性方面评估68Ga-NODAGA-BMS986192。还在非人灵长类食蟹猴中研究了该探针的动态生物分布和辐射剂量测定。
结果:制备放射化学纯度高于99%的68Ga-NODAGA-BMS986192。使用68Ga-NODAGA-BMS986192的PET成像在注射后1小时有效地描绘了hPD-L1-B16F10肿瘤。使用体内阻断测定和离体生物分布研究进一步证实了该探针的PD-L1靶向能力。小鼠和食蟹猴模型的PET动态成像显示通过肾脏途径快速清除探针,这对应于PET图像的低背景信号。该探针在雄性食蟹猴中还表现出良好的辐射剂量测定曲线,全身有效剂量为6.34E-03mSv/MBq。
结论:68Ga-NODAGA-BMS986192是用于人类PD-L1可视化的可行且安全的工具。我们的研究还提供了有关使用基于Adnectin的探针进行靶向PET成像的潜力的有价值的信息。
BACKGROUND: Adnectin is a protein family derived from the 10th type III domain of human fibronectin (10Fn3) with high-affinity targeting capabilities. Positron emission tomography (PET) probes derived from anti-programmed death ligand-1 (PD-L1) Adnectins, including 18F- and 68Ga-labeled BMS-986192, are recently developed for the prediction of patient response to immune checkpoint blockade. The 68Ga-labeled BMS-986192, in particular, is an attractive probe for under-developed regions due to the broader availability of 68Ga. However, the pharmacokinetics and biocompatibility of 68Ga-labeled BMS-986192 are still unknown, especially in non-human primates, impeding its further clinical translation.
METHODS: We developed a variant of 68Ga-labeled BMS-986192 using 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA) as the radionuclide-chelator. The resultant probe, 68Ga-NODAGA-BMS986192, was evaluated in terms of targeting specificity using a bilateral mouse tumor model inoculated with wild-type B16F10 and B16F10 transduced with human PD-L1 (hPD-L1-B16F10). The dynamic biodistribution and radiation dosimetry of this probe were also investigated in non-human primate cynomolgus.
RESULTS: 68Ga-NODAGA-BMS986192 was prepared with a radiochemical purity above 99%. PET imaging with 68Ga-NODAGA-BMS986192 efficiently delineated the hPD-L1-B16F10 tumor at 1 h post-injection. The PD-L1-targeting capability of this probe was further confirmed using in vivo blocking assay and ex vivo biodistribution studies. PET dynamic imaging in both mouse and cynomolgus models revealed a rapid clearance of the probe via the renal route, which corresponded to the low background signals of the PET images. The probe also exhibited a favorable radiation dosimetry profile with a total-body effective dose of 6.34E-03 mSv/MBq in male cynomolgus.
CONCLUSIONS: 68Ga-NODAGA-BMS986192 was a feasible and safe tool for the visualization of human PD-L1. Our study also provided valuable information on the potential of targeted PET imaging using
Adnectin-based probes.