464 Dual-Strike Immunotherapy: Intracranial PD-L1–Directed MC9999 CAR T Cells Eradicate Glioblastoma and Reprogram the Tumor Microenvironment

作者：Loizos Michaelides, Jesus Emiliano Sanchez-Garavito, Maria Jose Ulloa Navas, Manuela Maria Aramburu-Berckemeyer, Rachel Whitehead, Yan Luo, Juan Pablo Navarro Garcia de Llano, Yaqing Qie, Mieu Brooks, Vanessa K. Jones, Haidong Dong, Hong Qin, Alfredo Quiñones-Hinojosa · 发表于：Neurosurgery · 年份：2026 · DOI：10.1227/neu.0000000000003964_464 · 研究领域：CAR-T cell therapy research、Cancer Immunotherapy and Biomarkers、Immunotherapy and Immune Responses

INTRODUCTION: Glioblastoma (GBM) continues to be one of the deadliest and most treatment-resistant brain tumors, largely due to its genetic diversity and highly immunosuppressive environment. PD-L1, an immune checkpoint ligand, is frequently expressed on both tumor cells and tumor-associated macrophages (TAMs), but notably absent in healthy brain tissue, making it an appealing target for therapeutic intervention. Our aim was to develop a therapy capable of tackling both the tumor and its supportive niche. METHODS: Using patient-derived GBM tissue, we validated PD-L1 expression via multiplex immunohistochemistry and single-cell RNA sequencing. MC9999 CAR T cells were assessed in vitro for cytotoxicity against PD-L1 tumor cells and autologous M2-like macrophages. in vivo efficacy was tested in orthotopic xenograft models following a single intracranial infusion, with animals monitored for up to 135 days. Mechanistic insights were obtained via single-cell transcriptomics and comparative analysis with human glioma datasets. RESULTS: MC9999 CAR T cells selectively eliminated PD-L1 expressing GBM cells and TAMs. A single dose was sufficient to completely clear tumors, with no recurrence and no evidence of systemic spread. Mechanistically, CD4+ CAR T cells induced IFNα/β signaling in tumor cells, while CD8+ T cells contributed through granzyme-mediated killing. Key genes upregulated post-treatment, including CTSS and PLAAT4, aligned with T-cell activation markers in clinical glioma ...