We describe the development of OncoFAP, an ultra-high-affinity ligand of fibroblast activation protein (FAP) for targeting applications with pan-tumoral potential. OncoFAP binds to human FAP with affinity in the subnanomolar concentration range and cross-reacts with the murine isoform of the protein. We generated various fluorescent and radiolabeled derivatives of OncoFAP in order to study biodistribution properties and tumor-targeting performance in preclinical models. Fluorescent derivatives selectively localized in FAP-positive tumors implanted in nude mice with a rapid and homogeneous penetration within the neoplastic tissue. Quantitative in vivo biodistribution studies with a lutetium-177–labeled derivative of OncoFAP revealed a preferential localization in tumors at doses of up to 1,000 nmol/kg. More than 30% of the injected dose had already accumulated in 1 g of tumor 10 min after intravenous injection and persisted for at least 3 h with excellent tumor-to-organ ratios. OncoFAP also served as a modular component for the generation of nonradioactive therapeutic products. A fluorescein conjugate mediated a potent and FAP-dependent tumor cell killing activity in combination with chimeric antigen receptor (CAR) T cells specific to fluorescein. Similarly, a conjugate of OncoFAP with the monomethyl auristatin E-based Vedotin payload was well tolerated and cured tumor-bearing mice in combination with a clinical-stage antibody-interleukin-2 fusion. Collectively, these data support the development of OncoFAP-based products for tumor-targeting applications in patients with cancer.

我们描述了 OncoFAP 的开发，这是一种成纤维细胞激活蛋白 (FAP) 的超高亲和力配体，用于靶向具有泛肿瘤潜力的应用。OncoFAP 以亚纳摩尔浓度范围内的亲和力与人 FAP 结合，并与该蛋白质的鼠类同种型发生交叉反应。我们生成了 OncoFAP 的各种荧光和放射性标记衍生物，以研究临床前模型中的生物分布特性和肿瘤靶向性能。荧光衍生物选择性地定位于植入裸鼠的 FAP 阳性肿瘤中，并在肿瘤组织内快速均匀地渗透。使用镥 177 标记的 OncoFAP 衍生物进行的体内生物分布定量研究表明，在高达 1,000 nmol/kg 的剂量下，肿瘤优先定位。静脉注射后 10 分钟，超过 30% 的注射剂量已经在 1 g 肿瘤中积累，并持续至少 3 小时，具有极好的肿瘤器官比。OncoFAP 还用作非放射性治疗产品生成的模块化组件。荧光素偶联物与荧光素特异性嵌合抗原受体 (CAR) T 细胞结合，介导了强大的 FAP 依赖性肿瘤细胞杀伤活性。同样，OncoFAP 与基于单甲基 auristatin E 的 Vedotin 有效载荷的结合物具有良好的耐受性，并与临床阶段的抗体-白细胞介素-2 融合体相结合，治愈了荷瘤小鼠。总的来说，这些数据支持开发基于 OncoFAP 的产品，用于癌症患者的肿瘤靶向应用。