99mTc 标记的促黄体生成素释放激素类似物作为癌症受体显像的临床前评估

Alfaya Lucía, Camacho Ximena, Cabrera Mirel, Tassano Marcos, Savio Eduardo, Reyes Laura, Paolino Andrea, García María Fernanda, Fernández Marcelo, Gambini Juan Pablo, Cabral Pablo

Área de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay,

Programa de Posgrado, Facultad de Química, Universidad de la República, Montevideo, Uruguay,

Oncology. 2025 Jul 11:1-13. doi: 10.1159/000542823.

INTRODUCTION

Breast cancer is the main cause of cancer-related mortality in women in the developed world. In particular, receptors of luteinizing hormone-releasing hormone (LHRH or GnRH) are overexpressed in this malignant disease. The aim of this study was to develop a new molecular probe [99mTc]Tc-HYNIC-GSG-LHRH(d-Lys6)/tricine/nicotinic acid (NA) as a novel molecular imaging agent for breast cancer.

METHODS

HYNIC-GSG-LHRH(D-Lys6) was acquired and radiolabeled with [99mTc]Tc. Radiochemical purity and stability under different conditions were evaluated by instant thin-layer chromatography (ITLC) and high-performance liquid chromatography. Lipophilicity was determined by the partition coefficient test. In vitro cell binding studies were performed in different human and mice breast cancer cell lines (MDA-MB-231, MDA-MB-435, MCF-7, BT474, and 4T1) as well as in normal murine fibroblasts (NIH-3T3) and CHO-K1 as a negative control. Biodistribution studies were performed in normal Balb/c mice and 4T1 tumor-bearing Balb/c mice up to 6 h post-injection (pi). SPECT/CT images were performed in 4T1 tumor-bearing Balb/c mice up to 5 h pi.

RESULTS

[99mTc]Tc-HYNIC-GSG-LHRH(d-Lys6)/tricine/NA complex was labeled with a high radiochemical purity (>98%) and remained stable for up to 4 h. It exhibited good hydrophilicity (log p = -2.82 ± 0.04) and also demonstrated significant and specific binding across all evaluated breast cancer cell lines. Biodistribution studies showed a high renal clearance and low nonspecific binding (<2% Act/g) in most organs, as well as appreciable tumor uptake (5.8 ± 0.5 % ID/g 1 h pi) and high tumor-to-muscle ratio (maximum of 30.5 ± 11.2 at 1 h pi). SPECT/CT imaging of 4T1-tumor-bearing Balb/c mice revealed results consistent with the biodistribution studies, showing a tumor-to-non-tumor ratio of greater than 3.5 at all evaluated time points. In vivo blocking studies confirmed specificity for the LHRH receptor.

CONCLUSIONS

[99mTc]Tc-HYNIC-GSG-LHRH(d-Lys6)/tricine/NA complex has shown significant potential for in vivo visualization of LHRH receptors expression in breast cancer.

引言

在发达国家，乳腺癌是女性癌症相关死亡的主要原因。特别是，促黄体生成素释放激素（LHRH或GnRH）受体在这种恶性疾病中过度表达。本研究的目的是开发一种新的分子探针[99mTc]Tc-HYNIC-GSG-LHRH（d-Lys6）/三羟甲基氨基甲烷/烟酸（NA），作为一种用于乳腺癌的新型分子成像剂。

方法

获取HYNIC-GSG-LHRH（D-Lys6）并用[99mTc]Tc进行放射性标记。通过即时薄层色谱法（ITLC）和高效液相色谱法评估不同条件下的放射化学纯度和稳定性。通过分配系数测试测定亲脂性。在不同的人源和鼠源乳腺癌细胞系（MDA-MB-231、MDA-MB-435、MCF-7、BT474和4T1）以及正常鼠成纤维细胞（NIH-3T3）和CHO-K1中进行体外细胞结合研究，将其作为阴性对照。在正常Balb/c小鼠和荷4T1肿瘤的Balb/c小鼠中进行生物分布研究，直至注射后（pi）6小时。在荷4T1肿瘤的Balb/c小鼠中直至pi后5小时进行SPECT/CT成像。

结果

[99mTc]Tc-HYNIC-GSG-LHRH（d-Lys6）/三羟甲基氨基甲烷/NA复合物以高放射化学纯度（>98%）进行标记，并在长达4小时内保持稳定。它表现出良好的亲水性（log p = -2.82 ± 0.04），并且在所有评估的乳腺癌细胞系中均显示出显著且特异性的结合。生物分布研究表明，在大多数器官中具有高肾清除率和低非特异性结合（<2%每克注射量），以及可观的肿瘤摄取（注射后1小时为5.8 ± 0.5%每克注射量）和高肿瘤与肌肉比值（注射后1小时最高为30.5 ± 11.2）。荷4T1肿瘤的Balb/c小鼠的SPECT/CT成像显示结果与生物分布研究一致，在所有评估时间点肿瘤与非肿瘤比值均大于3.5。体内阻断研究证实了对LHRH受体的特异性。