缓释靶向GRPR和αvβ3的前列腺癌诊疗一体化分子探针的设计合成及体内外实验研究

This study aims to explore a precise and individualized radionuclide theranostic system in prostate cancer. Recently, therapeutic concepts for peptide receptor radiotherapy (PRRT) have been introduced. The concept of theranostics combines imaging and therapy such that imaging compounds are used for non-invasive detection and quantification of receptor expression. Gastrin-releasing peptide receptor (GRPR) and integrin αvβ3 are significantly upregulated in prostate cancer, thus serving as important biomarkers and therapeutic targets. Previously, we have document the first-in-human application of dual GRPR and αvβ3 receptor targeting PET radiotracer 68Ga-BBN-RGD, which played an additive role in staging and detecting prostate cancer and provided guidance for internal radiation therapy. However, as therapeutics because of their unfavorable pharmacokinetics, in particular rapid blood clearance that prevents achieving therapeutic concentrations. To address the need for additional methods to improve the blood half-life of drugs and molecular imaging agents, we made use of molecules with high affinity for albumin. We previously developed a truncated derivative of Evans Blue (EB) that, upon radiolabeling, allows imaging of blood volume, due to EB’s affinity for albumin. The new NMEB-BBN-RGD derivatives are planned to be prepared by linking the truncated EB and then labeled with 68Ga and 177Lu. The binding affinity of NMEB-BBN-RGD to GRPR and integrin αvβ3 will be compared with BBN-RGD in competition assays using PC-3 cells, Cellular uptake and internalization, in vitro and in vivo stability, microPET imaging with 68Ga-NMEB-BBN-RGD and 177Lu-NMEB-BBN-RGD with nanoSPECT/CT in PC-3 xenografts will be assessed. Then conjugation to therapeutic agents prolonged circulation half-life and enhanced tumor accumulation in GRPR and αvβ3 expressing primary and metastasis tumors targeting theranostic agents development and optimization. A novel imaging technique is expected to be established for clinical application. It is also expected that a translational platform based on the molecular imaging and precise individualized therapeutical approaches will be established for prostate cancer.

近年来，以胃泌素释放肽受体(GRPR)和整合素αvβ3受体为作用靶点的受体介导显像和分子靶向治疗取得了很大进展。课题组前期在国际上率先进行了双靶向GRPR和αvβ3分子探针68Ga-BBN-RGD用于前列腺癌分子显像的转化研究，通过短半衰期同位素标记示踪量的探针，无创地监测肿瘤细胞和分子水平的活动，提供特定的肿瘤表型影像。拟进一步通过顶端结构修饰EB通过环状螯合剂NOTA连接修饰，设计合成以GRPR和αvβ3受体为靶向的长效缓释探针，进一步延长生物半衰期、提高肿瘤细胞的摄取。通过正电子核素68Ga与治疗核素177Lu进行标记，测定探针的体外稳定性，测定探针在动物体内的药代动力学参数及生物分布数据，建立荷PC-3前列腺癌裸鼠模型行microPET和 nanoSPECT/CT显像，对探针进行体内外评价。希望最终实现基于GRPR和αvβ3前列腺癌分子靶向诊疗平台的构建。

胃泌素释放肽受体(GRPR)和整合素αvβ3受体在前列腺癌等人类多种肿瘤细胞表面高表达，成为肿瘤受体介导的分子显像和核素分子治疗的重要靶点。我们在国际上率先进行了双靶向GRPR和αvβ3分子探针用于前列腺癌分子显像的转化研究，通过短半衰期同位素标记示踪量的探针，无创地监测肿瘤细胞和分子水平的活动，提供特定的肿瘤表型影像。我们希望通过进一步结构修饰设计合成以GRPR和αvβ3受体为靶向的长效缓释探针，进一步延长生物半衰期、提高肿瘤细胞的摄取，并通过正电子核素68Ga与治疗核素177Lu进行标记，对探针进行体内外评价，实现基于GRPR和αvβ3的分子靶向诊疗一体化。.我们成功构建和优化了针对GRPR和αvβ3受体显像方法，包括针对GRPR受体激动剂及拮抗剂特异性PET和 SPECT分子显像，实现了前列腺癌GRPR和αvβ3受体表达的活体、精确、定量测量。我们建立了177Lu-GRPR和αvβ3 SPECT/CT用于GRPR和αvβ3受体显像的方法和条件，建立了完善、规范和重复性好的标准化检查程序和半定量方法学的构建。.我们通过偶联血浆白蛋白结合剂顶端修饰EB螯合，合成缓释靶向性探针NMEB/DMEB-BBN-RGD，进行标记及稳定性测试，同时设计合成针对GRPR和αvβ3受体缓释靶向性NMEB/DMEB-RGD，NMEB/DMEB-BBN，NMEB/DMEB-RM26，用于不同肿瘤模型的筛选及对照。我们成功构建了基于正电子核素68G及治疗核素177Lu标记的68Ga/177Lu-NMEB/DMEB-BBN-RGD，68Ga/177Lu-NMEB/DMEB-RGD，68Ga/177Lu-NMEB/DMEB-BBN，68Ga/177Lu-NMEB/DMEB-RM26诊疗一体化探针体系，我们发现通过偶联血浆白蛋白结合剂顶端修饰EB螯合的缓释靶向受体探针能够显著提高其有效生物半衰期，同时增加肿瘤细胞的摄取，增强杀伤肿瘤细胞的效力。在完成相关目标后并结合研究中的结果，我们进一步扩展至其他受体特异性肿瘤的剂量学研究，进一步发现通过偶联血浆白蛋白结合剂顶端修饰EB螯合的缓释靶向性探针，在提高核素靶向治疗肿瘤有效剂量从而增强肿瘤治疗疗效中具有重要意义。