The hepatocyte growth factor (HGF) binding antibody rilotumumab (AMG102) was modified for use as a ⁸⁹Zr-based immuno-PET imaging agent to noninvasively determine the local levels of HGF protein in tumors. Because recent clinical trials of HGF-targeting therapies have been largely unsuccessful in several different cancers (e.g., gastric, brain, lung), we have synthesized and validated ⁸⁹Zr-DFO-AMG102 as a companion diagnostic for improved identification and selection of patients having high local levels of HGF in tumors. To date, patient selection has not been performed using the local levels of HGF protein in tumors. Methods: The chelator p-SCN-Bn-DFO was conjugated to AMG102, radiolabeling with ⁸⁹Zr was performed in high radiochemical yields and purity (>99%), and binding affinity of the modified antibody was confirmed using an enzyme-linked immunosorbent assay (ELISA)–type binding assay. PET imaging, biodistribution, autoradiography and immunohistochemistry, and ex vivo HGF ELISA experiments were performed on murine xenografts of U87MG (HGF-positive, MET-positive) and MKN45 (HGF-negative, MET-positive) and 4 patient-derived xenografts (MET-positive, HGF unknown). Results: Tumor uptake of ⁸⁹Zr-DFO-AMG102 at 120 h after injection in U87MG xenografts (HGF-positive) was high (36.8 ± 7.8 percentage injected dose per gram [%ID/g]), whereas uptake in MKN45 xenografts (HGF-negative) was 5.0 ± 1.3 %ID/g and a control of nonspecific human IgG ⁸⁹Zr-DFO-IgG in U87MG tumors was 11.5 ± 3.3 %ID/g, demonstrating selective uptake in HGF-positive tumors. Similar experiments performed in 4 different gastric cancer patient-derived xenograft models showed low uptake of ⁸⁹Zr-DFO-AMG102 (∼4–7 %ID/g), which corresponded with low HGF levels in these tumors (ex vivo ELISA). Autoradiography, immunohistochemical staining, and HGF ELISA assays confirmed that elevated levels of HGF protein were present only in U87MG tumors and that ⁸⁹Zr-DFO-AMG102 uptake was closely correlated with HGF protein levels in tumors. Conclusion: The new immuno-PET imaging agent ⁸⁹Zr-DFO-AMG102 was successfully synthesized, radiolabeled, and validated in vitro and in vivo to selectively accumulate in tumors with high local levels of HGF protein. These results suggest that ⁸⁹Zr-DFO-AMG102 would be a valuable companion diagnostic tool for the noninvasive selection of patients with elevated local concentrations of HGF in tumors for planning any HGF-targeted therapy, with the potential to improve clinical outcomes.

修改了肝细胞生长因子（HGF）结合抗体rilotumumab（AMG102），用作基于⁸⁹ Zr的免疫PET显像剂，以无创地确定肿瘤中HGF蛋白的局部水平。由于针对HGF的疗法的最新临床试验在几种不同的癌症（例如，胃癌，脑癌，肺癌）中均未取得成功，因此我们合成并验证了^89种Zr-DFO-AMG102可作为辅助诊断方法，以改善对患有以下疾病的患者的识别和选择肿瘤中HGF的局部水平很高。迄今为止，尚未使用肿瘤中局部水平的HGF蛋白进行患者选择。方法：将螯合剂p -SCN-Bn-DFO与AMG102偶联，用^89进行放射性标记Zr以高放射化学产率和纯度（> 99％）进行，并且修饰的抗体的结合亲和力通过酶联免疫吸附测定（ELISA）型结合测定得以证实。在U87MG（HGF阳性，MET阳性）和MKN45（HGF阴性，MET阳性）的鼠异种移植物和4个患者来源的异种移植物（MET）上进行PET成像，生物分布，放射自显影和免疫组化以及离体HGF ELISA实验-阳性，HGF未知）。结果： U87MG异种移植物（HGF阳性）在注射后120 h时，对⁸⁹ Zr-DFO-AMG102的肿瘤摄取很高（每克注射剂量的36.8±7.8％[％ID / g]），而MKN45异种移植物（HGF）的摄取-阴性）为5.0±1.3％ID / g，对照为非特异性人IgG ⁸⁹U87MG肿瘤中的Zr-DFO-IgG为11.5±3.3％ID / g，表明在HGF阳性肿瘤中有选择性摄取。在4种不同的胃癌患者异种移植模型中进行的类似实验显示，摄取低的⁸⁹ Zr-DFO-AMG102（约4-7％ID / g），这与这些肿瘤中的低HGF水平相对应（离体ELISA）。放射自显影，免疫组织化学染色和HGF ELISA分析证实，仅在U87MG肿瘤中存在高水平的HGF蛋白，并且⁸⁹ Zr-DFO-AMG102的摄取与肿瘤中HGF的蛋白水平密切相关。结论：新型免疫PET显像剂⁸⁹Zr-DFO-AMG102已成功合成，放射性标记并在体外和体内进行了验证，可以选择性地在具有高局部HGF蛋白水平的肿瘤中蓄积。这些结果表明，⁸⁹ Zr-DFO-AMG102将成为有价值的伴随诊断工具，用于无创选择肿瘤中局部高浓度HGF的患者，以计划任何以HGF为靶标的治疗方案，并有可能改善临床疗效。