Abstract：
Thyroid cancer is the most common endocrine cancer, with differentiated thyroid cancers (DTCs) accounting for 95% of diagnoses. While most DTC patients are diagnosed and treated with radioiodine (RAI), up to 20% of DTC patients become RAI refractory (RAI-R). RAI-R patients have significantly reduced survival rates compared to patients who remain RAI-avid. This study explores [89Zr]Zr-TR1402 as a thyroid-stimulating hormone receptor (TSHR)-targeted PET radiopharmaceutical for DTC. [89Zr]Zr-TR1402 was synthesized with a molar activity of 25.9 MBq/nmol by conjugating recombinant human TSH (rhTSH) analogue TR1402 to chelator p-SCN-Bn-deferoxamine (DFO) in a molar ratio of 3:1 (DFO/TR1402) and radiolabeling with 89Zr (t1/2 = 78.4 h, β+ = 22.7%). As TSHR is absent in commonly available DTC-derived cell lines, TSHR was reintroduced via stable transduction by delivering a lentivirus containing the full-length coding region of the human TSHR gene. Receptor-mediated uptake of [89Zr]Zr-TR1402 was evaluated in vitro in stably transduced TSHR+ and wild-type TSHR- DTC cell lines. In vivo PET imaging was performed on Days 1-3 postinjection in male and female athymic nude mice bearing TSHR+ and TSHR- xenografts, along with ex vivo biodistribution on Day 3 postinjection. In vitro uptake of 1 nM [89Zr]Zr-TR1402 was significantly higher in TSHR+ THJ529T (P < 0.0001) and FTC133 (P < 0.01) cells than in TSHR- THJ529T and FTC133 cells. This uptake was shown to be specific in both TSHR+ THJ529T (P < 0.0001) and TSHR+ FTC133 (P < 0.0001) cells by blocking uptake with 250 nm DFO-TR1402. In vivo PET imaging showed accumulation of [89Zr]Zr-TR1402 in TSHR+ tumors, which was the highest on Day 1. In the male FTC133 xenograft model, ex vivo biodistribution confirmed a significant difference (P < 0.001) in uptake between FTC133+ (1.3 ± 0.1%ID/g) and FTC133- (0.8 ± 0.1%ID/g) tumors. A significant difference (P < 0.05) in uptake was also seen in the male THJ529T xenograft model between THJ529T+ (1.8 ± 0.6%ID/g) and THJ529T- (0.8 ± 0.4%ID/g) tumors. The in vitro and in vivo accumulation of [89Zr]Zr-TR1402 in TSHR-expressing DTC cell lines support the continued preclinical optimization of this approach.
摘要：
甲状腺癌是最常见的内分泌肿瘤,分化型甲状腺癌(DTC)占诊断的95%。虽然大多数DTC患者诊断和治疗放射性碘（RAI），高达20％的DTC患者成为RAI难治性（RAI-R）。与RAI-R患者相比，RAI-R患者的生存率显着降低。本研究探讨了[89Zr]Zr-TR1402作为DTC的促甲状腺激素受体（TSHR）靶向PET放射性药物。[89Zr]Zr-TR1402是通过将重组人TSH（rhTSH）类似物TR1402与螯合剂p-SCN-Bn-去铁胺（DFO）以摩尔比为3：1（DFO/TR1402）并用89Zr（t1/2=78.4h，β+=22.7%）。由于TSHR在常见的DTC衍生细胞系中不存在，通过递送含有人TSHR基因全长编码区的慢病毒,通过稳定转导再引入TSHR。在稳定转导的TSHR+和野生型TSHR-DTC细胞系中体外评估受体介导的[89Zr]Zr-TR1402的摄取。在带有TSHR和TSHR-异种移植物的雄性和雌性无胸腺裸鼠注射后第1-3天进行体内PET成像，以及注射后第3天的离体生物分布。TSHR+THJ529T(P<0.0001)和FTC133(P<0.01)细胞对1nM[89Zr]Zr-TR1402的体外摄取显著高于TSHR-THJ529T和FTC133细胞。通过用250nmDFO-TR1402阻断摄取,显示这种摄取在TSHR+THJ529T(P<0.0001)和TSHR+FTC133(P<0.0001)细胞中都是特异性的。体内PET成像显示[89Zr]Zr-TR1402在TSHR+肿瘤中积累，这是第一天最高的。在雄性FTC133异种移植模型中，离体生物分布证实了FTC133+(1.3±0.1%ID/g)和FTC133-(0.8±0.1%ID/g)肿瘤之间的摄取的显著差异(P<0.001)。在男性THJ529T异种移植模型中,在THJ529T+(1.8±0.6%ID/g)和THJ529T-(0.8±0.4%ID/g)肿瘤之间也观察到摄取的显著差异(P<0.05)。[89Zr]Zr-TR1402在表达TSHR的DTC细胞系中的体外和体内积累支持该方法的持续临床前优化。
