背景：免疫检查点抑制剂（ICI）常规用于晚期透明细胞肾细胞癌（ccRCC）。然而，相当一部分患者对 ICI 治疗没有反应。放射治疗是一种很有前景的提高 ICI 反应率的方法，因为它可以产生抗肿瘤免疫力。靶向放射性核素治疗（TRT）是一种全身放射治疗，非常适合转移性癌症的精确照射。因此，本研究的目的是探索联合 TRT、针对 ccRCC 中过度表达的碳酸酐酶 IX (CAIX)、使用 [177Lu]Lu-DOTA-hG250 和 ICI 治疗 ccRCC 的潜力。方法：在本研究中，我们评估了[177Lu]Lu-DOTA-hG250联合aPD-1/a-CTLA-4 ICI的治疗和免疫学作用。首先，在携带Renca-CAIX或CT26-CAIX肿瘤的BALB/cAnNRj小鼠中研究[ 177Lu]Lu-DOTA-hG250的生物分布。 Renca-CAIX 和 CT26-CAIX 肿瘤的特点分别是 T 细胞浸润较差与广泛，以及 PD-L1 表达同质与异质。通过剂量测定法估计肿瘤吸收的辐射剂量。随后，通过监测肿瘤生长和存活来评估有和没有ICI的[177Lu]Lu-DOTA-hG250 TRT功效。通过在治疗前和治疗后 5 或 8 天收集肿瘤组织，并通过免疫组织化学、流式细胞术和 RNA 分析进行分析，研究治疗引起的肿瘤微环境变化。结果：生物分布研究表明，两种肿瘤模型中 [177Lu]Lu-DOTA-hG250 均被肿瘤高摄取。在 Renca-CAIX 荷瘤小鼠中进行的剂量递增治疗研究表明，[177Lu]Lu-DOTA-hG250 具有剂量依赖性抗肿瘤功效，并且具有显着的治疗协同作用，包括在假定的亚治疗剂量（4 MBq，没有显着差异）时完全缓解。与 aPD-1 aCTLA-4 联合使用。在 4 MBq [177Lu]Lu-DOTA-hG250 a-PD1 的 CT26-CAIX 模型中获得了类似的结果。对治疗肿瘤的离体分析揭示了联合治疗后 TME 中的 DNA 损伤、T 细胞浸润和免疫信号通路的调节。结论：亚治疗[177Lu]Lu-DOTA-hG250 联合 ICI 显示出优越的治疗效果并显着改变了 TME。我们的结果强调了在临床环境中研究这种联合治疗对于晚期 ccRCC 患者的重要性。进一步的研究应集中于未来如何最佳地应用联合治疗。© 作者。

Background: Immune checkpoint inhibitors (ICI) are routinely used in advanced clear cell renal cell carcinoma (ccRCC). However, a substantial group of patients does not respond to ICI therapy. Radiation is a promising approach to increase ICI response rates since it can generate anti-tumor immunity. Targeted radionuclide therapy (TRT) is a systemic radiation treatment, ideally suited for precision irradiation of metastasized cancer. Therefore, the aim of this study is to explore the potential of combined TRT, targeting carbonic anhydrase IX (CAIX) which is overexpressed in ccRCC, using [177Lu]Lu-DOTA-hG250, and ICI for the treatment of ccRCC. Methods: In this study, we evaluated the therapeutic and immunological action of [177Lu]Lu-DOTA-hG250 combined with aPD-1/a-CTLA-4 ICI. First, the biodistribution of [177Lu]Lu-DOTA-hG250 was investigated in BALB/cAnNRj mice bearing Renca-CAIX or CT26-CAIX tumors. Renca-CAIX and CT26-CAIX tumors are characterized by poor versus extensive T-cell infiltration and homogeneous versus heterogeneous PD-L1 expression, respectively. Tumor-absorbed radiation doses were estimated through dosimetry. Subsequently, [177Lu]Lu-DOTA-hG250 TRT efficacy with and without ICI was evaluated by monitoring tumor growth and survival. Therapy-induced changes in the tumor microenvironment were studied by collection of tumor tissue before and 5 or 8 days after treatment and analyzed by immunohistochemistry, flow cytometry, and RNA profiling. Results: Biodistribution studies showed high tumor uptake of [177Lu]Lu-DOTA-hG250 in both tumor models. Dose escalation therapy studies in Renca-CAIX tumor-bearing mice demonstrated dose-dependent anti-tumor efficacy of [177Lu]Lu-DOTA-hG250 and remarkable therapeutic synergy including complete remissions when a presumed subtherapeutic TRT dose (4 MBq, which had no significant efficacy as monotherapy) was combined with aPD-1+aCTLA-4. Similar results were obtained in the CT26-CAIX model for 4 MBq [177Lu]Lu-DOTA-hG250 + a-PD1. Ex vivo analyses of treated tumors revealed DNA damage, T-cell infiltration, and modulated immune signaling pathways in the TME after combination treatment. Conclusions: Subtherapeutic [177Lu]Lu-DOTA-hG250 combined with ICI showed superior therapeutic outcome and significantly altered the TME. Our results underline the importance of investigating this combination treatment for patients with advanced ccRCC in a clinical setting. Further investigations should focus on how the combination therapy should be optimally applied in the future.© The author(s).