HER2:V2亲合体-培美曲塞分子探针构建及肺腺癌靶向诊疗的应用基础研究

HER2 is now available for effective target for breast cancer treatment, but HER2 in non small cell lung cancer especially in lung adenocarcinoma was also high expression. Therefore, research on HER2 target for lung cancer diagnosis and therapeutic also has an important significance. Based on our previous studies, this research constructs the new HER2:V2 affibody - pemetrexed molecular probe, marking the molecular probe with radionuclide technetium. The specific uptake and biodistribution of the 99mTc- HER2:V2 - pemetrexed molecular probe are studied from 3 different HER2 expression level lung adenocarcinoma cells and animal model in vitro or vivo. At the same time, using Her2:V2 affibody and the HER2 positive lung adenocarcinoma cell receptor targeting binding transport pemetrexed to the tumor site so as to improve the efficacy of chemotherapy drugs on tumor treatment, open up a new way. The new molecular probe can showed specific uptake of HER2 positive pulmonary adenocarcinoma cells in vivo molecular imaging, So realize the HER2 positive lung adenocarcinoma targeting diagnosis and targeting therapy. Therefore, the novel HER2:V2 affibody – pemetrexed molecular probe is of important clinical significance in the targeting diagnosis , targeting chemotherapy and therapeutic evaluation of lung adenocarcinoma.

HER2现已成为乳腺癌诊疗的有效靶点，但HER2在非小细胞肺癌尤其是肺腺癌中也呈高表达，研究HER2为靶点的肺腺癌诊断、治疗也具有重要意义。在以往研究基础上，本研究构建新型HER2:V2亲和体-培美曲塞分子探针，用放射性核素锝标记该分子探针, 从3种不同HER2表达的肺腺癌细胞和动物模型活体水平研究新型核素锝标记HER2:V2亲和体-培美曲塞分子探针被HER2表达的肺腺癌特异性摄取与体内分布，同时利用Her2:V2亲和体与HER2阳性的肺腺癌细胞受体结合特性将培美曲塞靶向运输至肿瘤部位从而提高化疗药物的疗效，开辟对肺腺癌治疗新途径。新型分子探针既可在活体内分子成像显示HER2阳性肺腺癌细胞的特异摄取，又以可对Her2高表达的肺腺癌的诊断和靶向治疗, 具有创新性。因此，本研究构建新型HER2:V2亲和体-培美曲塞分子探针对肺腺癌的诊断、靶向化疗和疗效评价具有重要意义。

肺腺癌靶向治疗近年取得了重要进展，但对于无可治疗基因突变的晚期肺腺癌患者，化疗为其一线治疗方案，但其化疗效果差，并有副作用成为治疗的瓶颈。本研究试图用受体介导化疗药物进行肿瘤治疗。人表皮生长因子受体2（HER2）在约35%非小细胞肺癌患者中高表达，是肺腺癌精准诊疗的重要靶点之一。本研究研发了新型HER2亲合体-培美曲塞诊疗一体化诊疗分子探针，试将培美曲塞靶向运输至肿瘤部位，从而实现对无可基因突变治疗的HER2阳性肺腺癌的个体化诊疗。构建合成HER2:V2亲合体-培美曲塞HER2靶向分子探针，用放射性核素99mTc通过螯合剂-GGGC进行标记，检测99mTc-ZHER2:V2-培美曲塞体内外稳定性，并对HER2阳性及HER2阴性细胞的靶向性及亲和力进行研究，研究分子探针在HER2阳性及阴性细胞荷瘤裸鼠模型体内分布及显像，探究肿瘤对分子探针的体内特异性摄取。同时进行ZHER2:V2-培美曲塞对肿瘤的治疗，并与培美曲塞治疗疗效与毒副作用进行对比评价，评价ZHER2:V2-培美曲塞的靶向化疗作用。结果表明，99mTc-ZHER2:V2-培美曲塞放射化学纯度较高为97.0 ± 0.3%，且在生理盐水及新鲜血清中稳定性好，在体外显示对HER2亲和力较好。生物分布显示对HER2阳性移植瘤对分子探针有明显的摄取，注射后4h肿瘤组织的%ID/g为2.6±1.0%ID/g，而对HER2阴性移植瘤，摄取不明显，为0.2±0.1%ID/g。SPECT显像结果提示HER2阳性A549细胞肿瘤组织有明显探针摄取，并且肿瘤部位的显像可被过量ZHER2:V2-培美曲塞阻断，说明探针具有靶向性。ZHER2:V2-培美曲塞的治疗作用明显优于培美曲塞，但毒副作用明显低于培美曲塞。总之，本研究成功构建ZHER2:V2-培美曲塞分子探针，使培美曲塞化疗药物具有HER2靶向性，在增强治疗作用的同时降低毒副作用，ZHER2:V2-培美曲塞作为诊疗一体化分子探针，在HER2阳性晚期肺腺癌的精准诊疗中发挥重要作用，具有重要理论与现实意义和应用前景。