我们研究了以放射性同位素标记的纤维母细胞激活蛋白(FAP)靶向放射性配体治疗物（OncoFAP和BiOncoFAP）与抗体细胞因子融合蛋白L19-白细胞介素 2 (L19-IL2)的组合对抗肿瘤的功效。方法：通过SPECT/CT研究不同摩尔量(3 vs. 250 nmol/kg)注射配体的177Lu-OncoFAP和177Lu-BiOncoFAP在携带皮下 HT-1080.hFAP 肿瘤的小鼠中的生物分布情况，并计算自吸收肿瘤和器官剂量。通过单独应用或与 L19-IL2 组合治疗评估放射性标记制剂（5MBq）的体内抗癌效果，包括植入 HT-1080.hFAP 和 SK-RC-52.hFAP 肿瘤。用基于质谱的蛋白质组学分析经 177Lu-BiOncoFAP、L19-IL2 或二者组合治疗的动物肿瘤样本，以确定癌症细胞和基质标记物以及免疫调节靶点上的治疗特征。结果：相比177Lu-OncoFAP（0.157±0.047 Gy/MBq），177Lu-BiOncoFAP表现出更高的自吸收剂量(0.293±0.123 Gy/MBq) 在FAP阳性肿瘤中（P = 0.01），并在高摩尔量注射配体时表现出有利的肿瘤-器官比率。单用L19-IL2或177Lu-BiOncoFAP治疗仅在有限数量的治疗动物中导致了肿瘤治愈。在177Lu-BiOncoFAP-加-L19-IL2联合治疗中，所有注射的小鼠均达到完全缓解（HT-1080.hFAP模型的7/7完全缓解，SK-RC-52.hFAP模型的4/4完全缓解），表明具有协同治疗作用。蛋白质组学研究揭示了一种基于自然杀伤细胞的作用机制，即组合治疗后肿瘤微环境中 granzyme 和 perforin 1 的表达显著增强。结论：在FAP阳性肿瘤治疗中，OncoFAP基于放射性配体治疗物与同时靶向白细胞介素2的组合显示出协同抗癌效果。这一实验结果应在未来的临床研究中得到证实。© 2023核医学与分子影像学学会。

We studied the antitumor efficacy of a combination of 177Lu-labeled radioligand therapeutics targeting the fibroblast activation protein (FAP) (OncoFAP and BiOncoFAP) with the antibody-cytokine fusion protein L19-interleukin 2 (L19-IL2) providing targeted delivery of interleukin 2 to tumors. Methods: The biodistribution of 177Lu-OncoFAP and 177Lu-BiOncoFAP at different molar amounts (3 vs. 250 nmol/kg) of injected ligand was studied via SPECT/CT in mice bearing subcutaneous HT-1080.hFAP tumors, and self-absorbed tumor and organ doses were calculated. The in vivo anticancer effect of 5 MBq of the radiolabeled preparations was evaluated as monotherapy or in combination with L19-IL2 in subcutaneously implanted HT-1080.hFAP and SK-RC-52.hFAP tumors. Tumor samples from animals treated with 177Lu-BiOncoFAP, L19-IL2, or both were analyzed by mass spectrometry-based proteomics to identify therapeutic signatures on cellular and stromal markers of cancer and on immunomodulatory targets. Results: 177Lu-BiOncoFAP led to a significantly higher self-absorbed dose in FAP-positive tumors (0.293 ± 0.123 Gy/MBq) than did 177Lu-OncoFAP (0.157 ± 0.047 Gy/MBq, P = 0.01) and demonstrated favorable tumor-to-organ ratios at high molar amounts of injected ligand. Administration of L19-IL2 or 177Lu-BiOncoFAP as single agents led to cancer cures in only a limited number of treated animals. In 177Lu-BiOncoFAP-plus-L19-IL2 combination therapy, complete remissions were observed in all injected mice (7/7 complete remissions for the HT-1080.hFAP model, and 4/4 complete remissions for the SK-RC-52.hFAP model), suggesting therapeutic synergy. Proteomic studies revealed a mechanism of action based on the activation of natural killer cells, with a significant enhancement of the expression of granzymes and perforin 1 in the tumor microenvironment after combination treatment. Conclusion: The combination of OncoFAP-based radioligand therapeutics with concurrent targeting of interleukin 2 shows synergistic anticancer effects in the treatment of FAP-positive tumors. This experimental finding should be corroborated by future clinical studies.© 2023 by the Society of Nuclear Medicine and Molecular Imaging.