Glypican-3 (GPC3) is a membrane-associated glycoprotein that is significantly upregulated in hepatocellular carcinomas (HCC) with minimal to no expression in normal tissues. The differential expression of GPC3 between tumor and normal tissues provides an opportunity for targeted radiopharmaceutical therapy to treat HCC, a leading cause of cancer-related deaths worldwide. Methods: DOTA-RYZ-GPC3 (RAYZ-8009) comprises a novel macrocyclic peptide binder to GPC3, a linker, and a chelator that can be complexed with different radioisotopes. The binding affinity was determined by surface plasma resonance and radioligand binding assays. Target-mediated cellular internalization was radiometrically measured at multiple time points. In vivo biodistribution, monotherapy, and combination treatments with ¹⁷⁷Lu or ²²⁵Ac were performed on HCC xenografts. Results: RAYZ-8009 showed high binding affinity to GPC3 protein of human, mouse, canine, and cynomolgus monkey origins and no binding to other glypican family members. Potent cellular binding was confirmed in GPC3-positive HepG2 cells and was not affected by isotope switching. RAYZ-8009 achieved efficient internalization on binding to HepG2 cells. Biodistribution study of ¹⁷⁷Lu-RAYZ-8009 showed sustained tumor uptake and fast renal clearance, with minimal or no uptake in other normal tissues. Tumor-specific uptake was also demonstrated in orthotopic HCC tumors, with no uptake in surrounding liver tissue. Therapeutically, significant and durable tumor regression and survival benefit were achieved with ¹⁷⁷Lu- and ²²⁵Ac-labeled RAYZ-8009, as single agents and in combination with lenvatinib, in GPC3-positive HCC xenografts. Conclusion: Preclinical in vitro and in vivo data demonstrate the potential of RAYZ-8009 as a theranostic agent for the treatment of patients with GPC3-positive HCC.

Glypican-3 (GPC3) 是一种膜相关糖蛋白，在肝细胞癌 (HCC) 中显着上调，而在正常组织中表达极少甚至不表达。肿瘤和正常组织之间 GPC3 的差异表达为靶向放射性药物治疗 HCC 提供了机会，HCC 是全球癌症相关死亡的主要原因。方法：DOTA-RYZ-GPC3 (RAYZ-8009) 包含 GPC3 的新型大环肽结合剂、接头和可与不同放射性同位素复合的螯合剂。通过表面等离子体共振和放射性配体结合测定法测定结合亲和力。在多个时间点对靶介导的细胞内化进行放射测量。对 HCC 异种移植物进行了¹⁷⁷ Lu 或²²⁵ Ac的体内生物分布、单一疗法和联合治疗。结果： RAYZ-8009 对人、小鼠、犬和食蟹猴来源的 GPC3 蛋白表现出高结合亲和力，并且与其他磷脂酰肌醇蛋白聚糖家族成员没有结合。在 GPC3 阳性 HepG2 细胞中证实了有效的细胞结合，并且不受同位素转换的影响。 RAYZ-8009 在与 HepG2 细胞结合时实现了有效的内化。¹⁷⁷ Lu-RAYZ-8009的生物分布研究显示肿瘤持续摄取和快速肾清除，而其他正常组织中摄取很少或没有摄取。在原位 HCC 肿瘤中也证实了肿瘤特异性摄取，而周围肝组织中没有摄取。¹⁷⁷ Lu 和²²⁵ Ac 标记的 RAYZ-8009 作为单药或与仑伐替尼联合使用，在 GPC3 阳性 HCC 异种移植物中取得了显着且持久的肿瘤消退和生存获益。结论：临床前体外和体内数据证明 RAYZ-8009 作为治疗 GPC3 阳性 HCC 患者的治疗诊断剂的潜力。