Takeda Pharmaceutical Co., Ltd., Cambridge, MA 02142, USA.
Molecular Cancer Imaging Facility, Dana Farber Cancer Institute, Boston, MA 02210, USA.
Molecules. 2023 Oct 18;28(20):7144. doi: 10.3390/molecules28207144.
Success of gene therapy relies on the durable expression and activity of transgene in target tissues. In vivo molecular imaging approaches using positron emission tomography (PET) can non-invasively measure magnitude, location, and durability of transgene expression via direct transgene or indirect reporter gene imaging in target tissues, providing the most proximal PK/PD biomarker for gene therapy trials. Herein, we report the radiosynthesis of a novel PET tracer [F]AGAL, targeting alpha galactosidase A (α-GAL), a lysosomal enzyme deficient in Fabry disease, and evaluation of its selectivity, specificity, and pharmacokinetic properties in vitro. [F]AGAL was synthesized via a Cu-catalyzed click reaction between fluorinated pentyne and an aziridine-based galactopyranose precursor with a high yield of 110 mCi, high radiochemical purity of >97% and molar activity of 6 Ci/µmol. The fluorinated AGAL probe showed high α-GAL affinity with of 30 nM, high pharmacological selectivity (≥50% inhibition on >160 proteins), and suitable pharmacokinetic properties (moderate to low clearance and stability in plasma across species). In vivo [F]AGAL PET imaging in mice showed high uptake in peripheral organs with rapid renal clearance. These promising results encourage further development of this PET tracer for in vivo imaging of α-GAL expression in target tissues affected by Fabry disease.
基因治疗的成功依赖于转基因在靶组织中的持久表达和活性。利用正电子发射断层扫描（PET）的体内分子成像方法可以通过直接转基因或间接报告基因成像，非侵入性地测量靶组织中转基因表达的幅度、位置和持久性，为基因治疗试验提供最接近的 PK/PD 生物标志物。本文报告了一种新型 PET 示踪剂[F]AGAL 的放射性合成，该示踪剂靶向法布里病中缺乏的溶酶体酶α-半乳糖苷酶 A（α-GAL），并评价了其在体外的选择性、特异性和药代动力学特性。[F]AGAL 是通过氟化戊炔与基于氮丙啶的半乳糖吡喃糖前体之间的 Cu 催化点击反应合成的，产率为 110mCi，放射化学纯度>97%，摩尔活性为 6Ci/µmol。该氟化 AGAL 探针表现出与α-GAL 的高亲和力（Kd 为 30nM），高药理学选择性（对>160 种蛋白质的抑制率≥50%），以及合适的药代动力学特性（在不同物种中具有中等至低清除率和在血浆中的稳定性）。在小鼠体内[F]AGAL PET 成像显示在外周器官中有高摄取，且具有快速的肾清除率。这些有希望的结果鼓励进一步开发这种 PET 示踪剂，用于法布里病靶组织中α-GAL 表达的体内成像。
