在这里,我们描述了与八齿缀合的抗前列腺特异性膜抗原(PSMA)微型抗体(IAB2MA),基于四个1-羟基吡啶-2-一配位单位(Lumi804[L804])的大环螯合剂,标记有89Zr(PET成像)和177Lu(放射性药物治疗),目的是开发更安全、更有效的前列腺癌治疗方案。方法:将L804与目前的金标螯合剂进行比较,DOTA和去铁胺(DFO),与IAB2MA缀合,用于在细胞结合中用177Lu和89Zr进行放射性标记,临床前生物分布,成像,剂量测定法,以及在PSMA阳性PC3-PIP荷瘤小鼠前列腺癌模型中的功效研究。结果:L804-IAB2MA与177Lu或89Zr的定量放射性标记(>99%放射化学产率)在环境温度下30分钟内实现,与DFO-IAB2MA的89Zr标记相当。相比之下,DOTA-IAB2MA在37°C下用177Lu放射性标记30分钟,放射化学产率约为90%。需要进一步净化。使用铕(III)作为发光替代品,在PC3-PIP细胞中证明了Eu-L804-IAB2MA与PSMA的高结合亲和力(解离常数,4.6±0.6nM)。所有4种放射性标记的构建体在30分钟后在PC3-PIP细胞中显示出比在PSMA阴性PC3-FLU细胞中明显更高的内化水平。177Lu-和89Zr-L804-IAB2MA在PC3-PIP肿瘤和所有检查的器官中的积累(即,心,肝脏,脾,脾肾,肌肉,唾液腺,泪腺,屠体,和骨)在注射后96和72h显着低于177Lu-DOTA-IAB2MA和89Zr-DFO-IAB2MA,分别。一般来说,SPECT/CT和PET/CT成像数据显示,放射性示踪剂之间肿瘤或肌肉的SUV均值没有显着差异。通过器官水平和体素水平剂量计算方法进行的剂量学分析表明,肿瘤中177Lu-DOTA-IAB2MA的吸收剂量明显更高,肾,肝脏,肌肉,和脾脏比177Lu-L804-IAB2MA。与未标记的小抗体对照相比,用单剂量的177Lu-L804-IAB2MA(18.4或22.2MBq)处理的PC3-PIP荷瘤小鼠表现出显著延长的存活和减小的肿瘤体积。在用177Lu-L804-IAB2MA或177Lu-DOTA-IAB2MA(18.4或22.2MBq)处理的小鼠组之间没有观察到存活的显著差异。与177Lu-D0TA-IAB2MA相比,用177Lu-L804-IAB2MA治疗导致肿瘤中更低的吸收剂量和更小的毒性。结论:89Zr-和177Lu-L804-IAB2MA可能是前列腺癌成像和治疗的有前途的治疗方案。
Here we describe an anti-prostate-specific membrane antigen (PSMA) minibody (IAB2MA) conjugated to an octadentate, macrocyclic chelator based on four 1-hydroxypyridin-2-one coordinating units (Lumi804 [L804]) labeled with 89Zr (PET imaging) and 177Lu (radiopharmaceutical therapy), with the goal of developing safer and more efficacious treatment options for prostate cancer. Methods: L804 was compared with the current gold standard chelators, DOTA and deferoxamine (DFO), conjugated to IAB2MA for radiolabeling with 177Lu and 89Zr in cell binding, preclinical biodistribution, imaging, dosimetry, and efficacy studies in the PSMA-positive PC3-PIP tumor-bearing mouse model of prostate cancer. Results: Quantitative radiolabeling (>99% radiochemical yield) of L804-IAB2MA with 177Lu or 89Zr was achieved at ambient temperature in under 30 min, comparable to 89Zr labeling of DFO-IAB2MA. In contrast, DOTA-IAB2MA was radiolabeled with 177Lu for 30 min at 37°C in approximately 90% radiochemical yield, requiring further purification. Using europium(III) as a luminescent surrogate, high binding affinity of Eu-L804-IAB2MA to PSMA was demonstrated in PC3-PIP cells (dissociation constant, 4.6 ± 0.6 nM). All 4 radiolabeled constructs showed significantly higher levels of internalization after 30 min in the PC3-PIP cells than in PSMA-negative PC3-FLU cells. The accumulation of 177Lu- and 89Zr-L804-IAB2MA in PC3-PIP tumors and all organs examined (i.e., heart, liver, spleen, kidney, muscle, salivary glands, lacrimal glands, carcass, and bone) was significantly lower than that of 177Lu-DOTA-IAB2MA and 89Zr-DFO-IAB2MA at 96 and 72 h after injection, respectively. Generally, SPECT/CT and PET/CT imaging data showed no significant difference in the SUVmean of the tumors or muscle between the radiotracers. Dosimetry analysis via both organ-level and voxel-level dose calculation methods indicated significantly higher absorbed doses of 177Lu-DOTA-IAB2MA in tumors, kidney, liver, muscle, and spleen than of 177Lu-L804-IAB2MA. PC3-PIP tumor-bearing mice treated with single doses of 177Lu-L804-IAB2MA (18.4 or 22.2 MBq) exhibited significantly prolonged survival and reduced tumor volume compared with unlabeled minibody control. No significant difference in survival was observed between groups of mice treated with 177Lu-L804-IAB2MA or 177Lu-DOTA-IAB2MA (18.4 or 22.2 MBq). Treatment with 177Lu-L804-IAB2MA resulted in lower absorbed doses in tumors and less toxicity than that of 177Lu-DOTA-IAB2MA. Conclusion: 89Zr- and 177Lu-L804-IAB2MA may be a promising theranostic pair for imaging and therapy of prostate cancer.