Longitudinal, non-invasive, in vivo monitoring of therapeutic gene expression is an unmet need for gene therapy (GT). Positron emission tomography (PET) radiotracers designed to bind to therapeutic proteins may provide a sensitive imaging platform to guide treatment response and dose optimization in GT. Herein, we evaluate a novel PET tracer ([18F]AGAL) for targeting α-galactosidase A (α-Gal A), an enzyme deficient in Fabry disease. Gla knockout mice were subjected to either GT with an adeno-associated virus encoding the human α-Gal A (AAVGLA) or recombinant α-Gal A for enzyme replacement studies. PET imaging, ex vivo autoradiography, biochemical analyses and radiation dosimetry were performed. [18F]AGAL exhibited pH-dependent binding to α-Gal A, suggesting recognition of the active enzyme residing within the acidified lysosomes. Imaging studies in the Fabry mouse model showed quick renal clearance with high radioactive uptake in the heart at 6 weeks that was sustained for 26 weeks after a single administration of AAVGLA, indicating effective and durable transgene expression from GT. Good concordance was achieved between in vivo PET imaging and ex vivo quantification of α-Gal A levels in biofluids and tissues. Biodistribution and dosimetry in non-human primate showed acceptable radiation exposure for multiple injections, demonstrating its potential for translation to clinical trial use.

中文翻译：

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使用正电子发射断层扫描和放射性示踪剂对法布里病基因治疗后治疗性酶表达进行纵向成像 [18F]AGAL


治疗性基因表达的纵向、无创 、体内监测是基因治疗 （GT） 未满足的需求。旨在与治疗性蛋白质结合的正电子发射断层扫描 （PET） 放射性示踪剂可能提供一个敏感的成像平台，以指导 GT 的治疗反应和剂量优化。在此，我们评估了一种新型 PET 示踪剂 （[18F]AGAL） 靶向 α-半乳糖苷酶 A （α-Gal A），一种法布里病缺乏的酶。Gla 敲除小鼠使用编码人 α-Gal A （AAVGLA） 的腺相关病毒或重组 α-Gal A 进行酶替代研究。进行 PET 成像、离 体放射自显影、生化分析和放射剂量测定。[18楼]AGAL 与 α-Gal A 表现出 pH 依赖性结合，表明识别酸化溶酶体内的活性酶。法布里小鼠模型的影像学研究显示，在单次给予 AAVGLA 后，6 周时肾脏清除迅速，心脏放射性摄取量高，持续 26 周，表明 GT 的转基因表达有效且持久。体内 PET 成像与生物体液和组织中 α-Gal A 水平的离 体定量之间 取得了良好的一致性。非人灵长类动物的生物分布和剂量测定显示多次注射的辐射暴露是可接受的，证明了其转化为临床试验的潜力。