用于乳腺癌精准高效诊疗的多核素标记Her2纳米抗体的研究

Breast cancer is of highly heterogeneous disease from the view of molecular characteristics and biologic behaviors, and 20-30% overexpress Her2. However, it is lack of clinical imaging scheme to dynamically monitor the whole-body Her2 expression, and traditional antibody (Ab)-based target therapy has serious drug resistance and invalidity. Nanobody (Nb) is a newly discovered smallest antibody, with the unique features of low molecular weight, easy expression/preparation, high stability, strong penetrability and easy humanization, and has the advantages of both traditional Ab and small molecule drugs, therefore, this study innovatively design to apply the imaging/treatment-paired nuclides radiolabeled Nb to solve the problems above. We will screen new Her2 nanobody(HNb) without Lys within the binding region, develop new chemical methods and chelate agents for paired multi-nuclide radiolabeling, construct the multinuclide-HNb system with the radioimmunotargeted theranostic capability, and overcome the dilemma of diagnosis and treatment of Her2-positive tumors. We will perform radionuclide imaging/treatment and PET/ SPECT imaging-guided dynamic effect evaluation from tumor cells and tissues to the whole-body level, build the foundation for the formation of precision diagnosis/treatment of Her2-positive breast cancer, make the benefit for the majority of breast cancer patients in the future, and enhance the role and value of radiopharmaceutical, nuclear medicine, nuclear chemistry and technology for the people's livelihood in China.

乳腺癌是分子特征与行为高度异质性疾病，20-30%的过度表达Her2，然而，临床上缺少全身动态监测Her2表达的显像方案，并且传统抗体(Ab)靶向治疗存在严重的耐药性与无效性。纳米抗体(Nb)是新近发现的最小抗体，具有分子量小、表达/制备容易、稳定性强、穿透性强、人源化简单等特点，兼具传统Ab和小分子药物的优势，因此，本项目创新设计显像与治疗配对核素标记Nb来解决上述难题。我们将筛选结合区内没有Lys的新型Her2纳米抗体(HNb)，研制其配对多核素标记的新型化学方法与螯合剂，构建具有放射免疫靶向诊疗功能的多核素-HNb体系，克服Her2阳性肿瘤的诊疗困境。我们将在肿瘤细胞、组织和活体全身层次，开展核素显像/治疗以及PET和SPECT显像指导动态疗效评价，为形成Her2阳性乳腺癌的精准诊疗模式奠定基础，将来造福广大的乳腺癌患者，增强放药、核医学、核化学与技术在国计民生中的作用和价值。

Her2靶向抗体治疗已经成为乳腺癌、胃癌等Her2高表达肿瘤患者的重要临床治疗选择和有效方案，然而由于肿瘤分子特征与行为的高度异质性以及传统抗体(Ab)靶向治疗存在严重的耐药性与无效性，临床上需要全身动态监测Her2表达的显像方案。因此，我们研究筛选新型Her2靶向纳米抗体(Nb)，构建基于多核素和NIR荧光标记Her2纳米抗体的放射性诊疗免疫探针制剂新体系。本项目的研究工作主要包括以下多个方面。. 1. 发展建立了高特异性、高亲和性的小规模Her2纳米抗体库的体外筛选及其通用型在体评价新方法：通过免疫骆驼、噬菌体展示、流式细胞仪、ELISA等，构建了Her2纳米抗体库；利用多核素与NIR荧光标记、不同Her2表达程度肿瘤模型和多模式分子影像PET/CT、SPECT/CT、NIRF等，发展了Her2纳米抗体的快速有效的在体评价新方式。. 2. 建立了通用型三羰基[99mTc]锝/[188Re]铼标记末端His-tag标签化纳米抗体的可靠方法，研制了用于Her2阳性肿瘤诊疗的99mTc/188Re-Her2Nb放射性探针新制剂：利用三羰基[99mTc]锝/[188Re]铼标记方法与SPECT/CT显像，发展了核素99mTc/188Re标记末端His-tag标签化纳米抗体的可靠通用方法，研制了Her2高靶向性放射性探针制剂99mTc/188Re-Her2Nb026等，将转化用于Her2高表达肿瘤靶向放射免疫SPECT显像与核素治疗。. 3. 研制了新型Her2靶向性PET/CT分子影像探针68Ga-Her2Nb026，开展了其Her2阳性肿瘤PET/CT显像和体内外性质评价：优化建立了基于螯合配位法的核素68Ga标记Her2Nb的优化体系，研制了Her2特异性强、Her2阳性肿瘤信号强、摄取高、PET/CT图像对比度高的新探针68Ga-Her2Nb026，将转化用于Her2高表达肿瘤靶向放射免疫PET显像检测与疗效评价。. 4. 研制了多种基于NIRF荧光分子标记Her2纳米抗体的NIRF荧光分子影像探针，开展了Her2阳性肿瘤模型NIRF光学显像评价：采取可靠通用化学反应方法，研制了多种新型Her2靶向性高、瘤内NIRF信号高、肿瘤显像明显的NIRF分子影像探针，将转化用于Her2高表达肿瘤靶向NIRF显像导航手术与指导光免疫治疗。