A CAIX Dual-Targeting Small-Molecule Probe for Noninvasive Imaging of ccRCC

• DOI: 10.1021/acs.molpharmaceut.4c00104
• Publication Date: 2024-06-04T04:41:02Z
• Authors: Chengxue He; Futao Liu; Jinping Tao; Zilei Wang; Jiayue Liu; Song Liu; Xiaoxia Xu; Liqiang Li; Feng Wang; Xianteng Yang; Hua Zhu; Zhi Yang
• Keywords: Male; Mice, Inbred BALB C; Mice, Nude; Gallium Radioisotopes; Xenograft Model Antitumor Assays; Kidney Neoplasms; Acetazolamide; Mice; Antigens, Neoplasm; Cell Line, Tumor; Molecular Probes; Positron Emission Tomography Computed Tomography; Positron-Emission Tomography; Animals; Humans; Tissue Distribution; Female; Radiopharmaceuticals; Carbonic Anhydrase IX; Carcinoma, Renal Cell

Carbonic anhydrase IX (CAIX), a zinc metal transmembrane protein, is highly expressed in 95% of clear cell renal cell carcinomas (ccRCCs). A positron emission tomography (PET) probe designed to target CAIX in nuclear medicine imaging technology can achieve precise positioning, is noninvasive, and can be used to monitor CAIX expression in lesions in real time. In this study, we constructed a novel acetazolamide dual-targeted small-molecule probe [68Ga]Ga-LF-4, which targets CAIX by binding to a specific amino acid sequence. After attenuation correction, the radiolabeling yield reached 66.95 ± 0.57% (n = 5) after 15 min of reaction and the radiochemical purity reached 99% (n = 5). [68Ga]Ga-LF-4 has good in vitro and in vivo stability, and in vivo safety and high affinity for CAIX, with a Kd value of 6.62 nM. Moreover, [68Ga]Ga-LF-4 could be quickly cleared from the blood in vivo. The biodistribution study revealed that the [68Ga]Ga-LF-4 signal was concentrated in the heart, lung, and kidney after administration, which was the same as that observed in the micro-PET/CT study. In a ccRCC patient-derived xenograft (PDX) model, the signal significantly accumulated in the tumor after administration, where it was retained for up to 4 h. After competitive blockade with LF-4, uptake at the tumor site was significantly reduced. The SUVmax of the probe [68Ga]Ga-LF-4 at the ccRCC tumor site was three times greater than that in the PC3 group with low CAIX expression at 30 min (ccRCC vs PC3:1.86 ± 0.03 vs 0.62 ± 0.01, t = 48.2, P < 0.0001). These results indicate that [68Ga]Ga-LF-4 is a novel small-molecule probe that targets CAIX and can be used to image localized and metastatic ccRCC lesions.