恶性黑色素瘤新型正电子显像剂18F-5-FPN的制备及临床前研究

摘要

Objective To prepare 18F-5-fluoro-N-(2-(diethylamino) ethyl) picolinamide (18F-5-FPN) and evaluate its binding affinity with melanin.Methods 5-bromo-N-(2-(diethylamino) ethyl)picolinamide (precursor) was synthesized and the structure was characterized by ultraviolet (UV),nuclear magnetic resonance (NMR) and mass spectrometry.18F-5-FPN was prepared with FX-XN module through nucleophilic substitution reaction.The product was purified and identified by HPLC.The binding specificity of 18F-5-FPN with melanin was demonstrated by in vitro study of cellular uptake,and in vivo static PET imaging of pigmented B16F10 and amelanotic A375m allografts.Biodistribution study was performed to evaluate the pharmacokinetics of 18F-5-FPN in vivo.Two-sample t test was used for data analysis.Results The structure of precursor was characterized by UV,1H NMR,13C NMR and mass spectrometry.18 F-5-FPN was successfully prepared with radiochemical yield of 5％-8％,radiochemical purity ＞95％ and the specific activity of 100-120 GBq/μmol.The cell uptake study showed that the uptakes of 18F-5-FPN in B16F10 cells at 30,60 and 120 min ((9.80±0.46) ％,(10.34±0.32) ％,(7.27±0.26)％) were significantly higher than those in A375m cells ((1.36±0.14)％,(1.75±0.12)％,(1.54±0.09)％;t =30.3,46.8,38.4,all P＜0.05),and the optimal uptakes were observed at 60 min for both cells.In static PET imaging,the tumors in B16F10-bearing mice were clearly visible with the uptake value of (18.20±3.21) ％ID/g and the T/B ratio of 19.17±10.03 at 1 h postinjection,while no tumor uptake was seen in A375m-bearing mice.The main clearance pathway of 18F-5-FPN was the renal system,which cleared the unbound tracer rapidly.Conclusions 18F-5-FPN can specifically target the melanin in vitro and in vivo with favorable pharmacokinetics and good T/B ratio.18F-5-FPN may be an ideal molecular probe for diagnosis of malignant melanoma.%目的 制备并鉴定正电子显像剂18F-5-氟-N-[2-(二乙氨基)乙基]吡啶甲酰胺(18F-5-FPN),并通过体内外实验评估其特异性靶向恶性黑色素瘤的能力.方法 合成标记前体5-溴-N-[2-(二乙胺基)乙基]吡啶甲酰胺,对其进行紫外光谱(UV)、核磁谱(NMR)和质谱等结构表征.利用FX-XN合成模块,经亲核取代反应由前体制得产物18F-5-FPN,然后通过HPLC对产物进行纯化及鉴定.用产生黑色素的B16F10细胞和不产生黑色素的A375m细胞进行体外细胞摄取实验,用2种细胞各自对应的荷瘤鼠进行PET静态显像,观察8F-5-FPN在正常小鼠体内的生物分布.采用两样本t检验分析数据.结果 UV、NMR和质谱等结构表征确定了标记前体的结构.18F-5-FPN的标记率为5％ ～ 8％,比活度为100～120 GBq/ μmol,放化纯＞95％.体外细胞摄取实验显示,B16F10细胞对18F-5-FPN的摄取率[(9.80±0.46)％、(10.34±0.32)％和(7.27±0.26)％]在30、60和120 min均明显高于A375m细胞[(1.36±0.14)％、(1.75±0.12)％和(1.54±0.09)％;t=30.3、46.8和38.4,均P＜0.05],2种细胞均在60 min时达最高细胞摄取率.PET静态显像示,B16F10荷瘤鼠肿瘤部位有明显放射性浓聚,1h放射性摄取值为(18.20±3.21) ％ID/g,T/B比值为19.17±10.03;而A375m荷瘤鼠肿瘤部位未见放射性浓聚.生物分布结果显示,18F-5-FPN主要通过泌尿系统快速排泄.结论 18F-5-FPN具备特异性靶向黑色素的能力,具有体内清除快、T/B比值高等特点,可作为无创性分子探针用于恶性黑色素瘤显像.