PO.CL05.05 · 临床研究
mTOR作为FLASH放疗的机制性生物标志物：对免疫调节性黑色素瘤治疗的意义
mTOR as a mechanistic biomarker of FLASH radiotherapy: Implications for immune-modulated melanoma treatment
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
FLASH放疗（FLASH-RT）以超高剂量率递送辐射，已成为一种有前景的治疗方式，可在不影响肿瘤控制的前提下减轻正常组织毒性。尽管临床前数据支持其组织保护特性，但其潜在的生物学机制仍未完全阐明。理解这些通路对于将FLASH整合入多模式癌症治疗至关重要。黑色素瘤是一种高度免疫原性且侵袭性强的皮肤癌，越来越多地采用免疫检查点抑制剂（如抗PD-1）进行治疗，然而许多患者会产生耐药。辐射可增强免疫原性，但毒性往往限制了剂量的提升。FLASH在减少副作用的同时与免疫治疗协同的潜力，为优化黑色素瘤治疗提供了令人振奋的机会。为研究免疫因素对FLASH效应的贡献，雌性BALB/c小鼠接受了以FLASH（约80 Gy/s）或常规剂量率（约0.5 Gy/s）递送的质子辐射，剂量为0、12或14 Gy。在治疗后第27天，使用数据非依赖采集质谱（DIA-MS）分析皮肤组织。基于机器学习的特征选择识别出可区分FLASH与常规治疗的胰蛋白酶消化肽段。mTOR（哺乳动物雷帕霉素靶蛋白，免疫信号的主要调控因子）及其结合伙伴Raptor在FLASH处理的皮肤中显著上调，提示存在一条独特的mTOR驱动通路。鉴于mTOR在通过干扰素和TGF-beta信号调节PD-L1表达和免疫抑制中的已知作用，我们推测FLASH可能增强免疫检查点阻断的疗效。使用体外和体内黑色素瘤模型，我们评估了FLASH或常规辐射联合或不联合抗PD-1治疗的应答。接受FLASH加抗PD-1治疗的小鼠在生存方面表现出令人鼓舞的改善，支持潜在的协同作用。免疫印迹和免疫荧光证实，FLASH后正常组织和肿瘤组织中磷酸化mTOR（Ser2448）及下游效应因子激活均增加。这些发现将mTOR确定为FLASH应答的候选生物标志物和机制性驱动因素，并支持在黑色素瘤及其他癌症中进一步开发基于mTOR、具有免疫应答性的FLASH策略。
查看英文原文 English abstract
FLASH radiotherapy (FLASH-RT), which delivers ultra-high dose rate radiation, has emerged as a promising modality that reduces normal tissue toxicity without compromising tumor control. While preclinical data support its tissue-sparing properties, the underlying biological mechanisms remain incompletely defined. Understanding these pathways is critical for integrating FLASH into multimodal cancer therapy.Melanoma, a highly immunogenic and aggressive skin cancer, is increasingly treated with immune checkpoint inhibitors (e.g., anti-PD-1), yet many patients develop resistance. Radiation can enhance immunogenicity, but toxicity often limits dose escalation. The potential for FLASH to synergize with immunotherapy while minimizing side effects presents an exciting opportunity to optimize melanoma treatment.To investigate the immune contributions to the FLASH effect, female BALB/c mice received proton radiation delivered as FLASH (~80 Gy/s) or conventional (~0.5 Gy/s) at 0, 12, or 14 Gy. At 27 days post-treatment, skin tissues were analyzed using Data Independent Acquisition-Mass Spectrometry (DIA-MS). Machine learning-based feature selection identified tryptic peptides that distinguished FLASH from conventional treatment. mTOR (mammalian target of rapamycin)-a master regulator of immune signaling-and its binding partner Raptor were significantly upregulated in FLASH-treated skin, suggesting a distinct mTOR-driven pathway.Given mTOR's known role in modulating PD-L1 expression and immune suppression via interferon and TGF-beta signaling, we hypothesized that FLASH may potentiate the efficacy of immune checkpoint blockade. Using in vitro and in vivo melanoma models, we evaluated responses to FLASH or conventional radiation with or without anti-PD-1 therapy. Mice treated with FLASH plus anti-PD-1 demonstrated promising improvements in survival, supporting potential synergy. Immunoblotting and immunofluorescence confirmed increased phospho-mTOR (Ser2448) and downstream effector activation in both normal and tumor tissues following FLASH.These findings identify mTOR as a candidate biomarker and mechanistic driver of FLASH responses and support further development of mTOR-informed, immune-responsive FLASH strategies in melanoma and other cancers.
利益披露 Disclosure
M. Hawkins, None..
J. Knight, None..
C. VanTassell, None..
L. Barnett, None..
G. L. Parkman, None..
D. Johnson-Erickson, None..
R. Rengan, None.