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 SUV_mean 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.

在这里，我们描述了一种与八齿大环螯合剂缀合的抗前列腺特异性膜抗原（PSMA）微型抗体（IAB2MA），该螯合剂基于四个 1-羟基吡啶-2-1 配位单元（Lumi804 [L804]），用⁸⁹ Zr 标记（PET 成像） ）和¹⁷⁷ Lu（放射药物治疗），目标是为前列腺癌开发更安全、更有效的治疗方案。方法：将 L804 与当前金标准螯合剂 DOTA 和去铁胺 (DFO) 进行比较，并与 IAB2MA 缀合，用¹⁷⁷ Lu 和⁸⁹ Zr 进行放射性标记，在 PSMA 阳性 PC3 中进行细胞结合、临床前生物分布、成像、剂量测定和疗效研究。 -PIP荷瘤小鼠前列腺癌模型。结果：在环境温度下，30 分钟内即可用¹⁷⁷ Lu 或⁸⁹ Zr 对 L804-IAB2MA 进行定量放射性标记（>99% 放射化学产率），与 DFO-IAB2MA 的⁸⁹ Zr 标记相当。相比之下，DOTA-IAB2MA 在 37°C 下用¹⁷⁷ Lu 放射性标记 30 分钟，放射化学产率约为 90%，需要进一步纯化。使用铕(III) 作为发光替代物，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 ± 0.6 nM）。 30 分钟后，所有 4 个放射性标记的构建体在 PC3-PIP 细胞中均表现出比 PSMA 阴性 PC3-FLU 细胞中显着更高的内化水平。 ^PC3 -PIP 肿瘤和^所有检查器官（即注射后96小时和72小时，心脏、肝脏、脾脏、肾脏、肌肉、唾液腺、泪腺、胴体和骨）分别显着低于¹⁷⁷ Lu-DOTA-IAB2MA和⁸⁹ Zr-DFO-IAB2MA 。一般来说，SPECT/CT 和 PET/CT 成像数据显示，放射性示踪剂之间的肿瘤或肌肉的 SUV_平均值没有显着差异。通过器官水平和体素水平剂量计算方法进行的剂量测定分析表明， ¹⁷⁷ Lu-DOTA-IAB2MA在肿瘤、肾、肝、肌肉和脾中的吸收剂量显着高于¹⁷⁷ Lu-L804-IAB2MA。与未标记的微型抗体对照相比，用单剂量¹⁷⁷ Lu-L804-IAB2MA（18.4 或 22.2 MBq）治疗的 PC3-PIP 荷瘤小鼠表现出显着延长的生存期和减小的肿瘤体积。在用¹⁷⁷ Lu-L804-IAB2MA 或¹⁷⁷ Lu-DOTA-IAB2MA (18.4 或 22.2 MBq) 治疗的小鼠组之间没有观察到存活率的显着差异。与¹⁷⁷ Lu-DOTA-IAB2MA 相比，用¹⁷⁷ Lu-L804-IAB2MA 治疗导致肿瘤中吸收剂量较低且毒性较小。结论： ⁸⁹ Zr- 和¹⁷⁷ Lu-L804-IAB2MA 可能是用于前列腺癌成像和治疗的有前景的治疗诊断对。