PO.IM01.14 · 免疫学
胶原结合型抗GITR抗体重塑免疫抑制性微环境并延长复发性胶质母细胞瘤的生存期
Collagen-binding anti-GITR antibody reshapes immunosuppressive microenvironment and prolongs survival in recurrent glioblastoma
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
复发性胶质母细胞瘤（rGBM）由于免疫治疗耐药性——由伴有调节性T细胞（Tregs）升高的免疫抑制性肿瘤微环境（TME）所驱动——仍然是致命的，中位生存期不足六个月。尽管已开发出如抗GITR（糖皮质激素诱导的TNFR相关蛋白）抗体等靶向Treg的抗体，但其向脑肿瘤的递送不佳限制了治疗疗效，因此需要新的药物递送策略。我们旨在鉴定用于向肿瘤选择性递送抗体的锚定物，并聚焦于I型和III型胶原（COLI&III），其在正常脑组织中含量极低，但在rGBM中高度上调。我们通过将血管性血友病因子（vWF）的COLI&III结合结构域（CBD）偶联到抗GITR抗体上，工程化构建了一种新型抗体CBD-αGITR。vWF天然仅在血管损伤、炎症和肿瘤部位结合暴露的胶原，而不作用于正常组织，从而为肿瘤特异性药物递送提供了潜在机制。我们使用临床相关的同基因rGBM小鼠模型、人源化小鼠模型以及患者来源的3D肿瘤切片培养，研究了CBD-αGITR的肿瘤选择性蓄积、免疫抑制性微环境重塑及抗肿瘤作用。通过荧光标记的生物分布检测，CBD-αGITR选择性地蓄积于rGBM肿瘤中，而不在正常脑组织或表达COLI/III的器官中蓄积。单细胞RNA测序显示，CBD-αGITR显著减少了GITR+ Tregs和耗竭的CD8+ T细胞（其表达中等水平的GITR），从而逆转免疫抑制性TME并促进抗肿瘤巨噬细胞和1型经典树突状细胞的募集。CBD-αGITR治疗（300μg，静脉注射1次）在两个独立的rGBM小鼠模型中实现了约20%的完全缓解（CR），而αGITR（非CBD）抗体则未显示出生存获益。此外，将CBD-αGITR与PD-1抑制剂联合进一步增强了抗肿瘤疗效，在rGBM小鼠模型中实现了67%的CR。我们已开发出用于临床应用的人源化CBD-αGITR，其在人源化rGBM小鼠模型中延长了生存期，并在患者来源的3D肿瘤切片培养中显著减少了人Treg。经COLI&III结合修饰的GITR抗体实现了选择性肿瘤蓄积、免疫重编程和强效肿瘤控制。该递送策略可应用于其他抗体，并有潜力显著推进rGBM的治疗方法。
查看英文原文 English abstract
Recurrent glioblastoma (rGBM) remains lethal with median survival under six months, due to immunotherapy resistance driven by immunosuppressive tumor microenvironment (TME) with elevated regulatory T cells (Tregs). Despite the development of Treg-targeting antibodies such as anti-GITR (Glucocorticoid-induced TNFR-related protein) antibody, their poor delivery to brain tumors has restricted therapeutic efficacy, necessitating novel drug delivery strategies. We aimed to identify anchors for selective antibody delivery to tumors and focused on Collagen type I and III (COLI&III), which are minimal in normal brain but highly upregulated in rGBM.We engineered a novel antibody, CBD-alphaGITR, by conjugating the COLI&III-binding domain (CBD) of von Willebrand Factor (vWF) to an anti-GITR antibody. vWF naturally binds to exposed collagen only at sites of vascular injury, inflammation, and tumor while sparing normal tissues, providing a potential mechanism for tumor-specific drug delivery. We investigated the tumor-selective accumulation, immunosuppressive microenvironment remodeling, and antitumor effects of CBD-alphaGITR using clinically relevant syngeneic rGBM mouse models, humanized mouse models, and patient-derived 3D tumor slice cultures.Using a fluorescently labeled biodistribution assay, CBD-alphaGITR selectively accumulated in rGBM tumors but not in normal brain or COLI/III-expressing organs. Single-cell RNA sequencing revealed that CBD-alphaGITR dramatically decreased GITR+ Tregs and exhausted CD8+ T cells (which express moderate levels of GITR), thereby reversing the immunosuppressive TME and promoting the recruitment of anti-tumor macrophages and type 1 conventional dendritic cells. CBD-alphaGITR treatment (300ug, i.v. 1x) achieved approximately 20% complete remission (CR) in two independent rGBM mouse models, while alphaGITR (non-CBD) antibody showed no survival benefit. Furthermore, combining CBD-alphaGITR with PD-1 inhibitor further enhanced antitumor efficacy, achieving 67% CR in rGBM mouse models. We have developed a humanized CBD-alphaGITR for clinical application, which demonstrated extended survival in humanized rGBM mouse models and significant human Treg reduction in patient-derived 3D tumor slice cultures.GITR antibody modified for COLI&III binding achieved selective tumor accumulation, immune reprogramming, and robust tumor control. This delivery strategy can be applied to other antibodies and has the potential to significantly advance treatment approaches for rGBM.
利益披露 Disclosure
J. Takei, None..
C. Wang, None..
K. Furudate, None..
O. Iwaloye, None..
L. Barr, None..
H. Ichie, None..
S. Tsuzuki, None..
J. Ishihara, None..
S. Osuka, None.