Open-Source Throttling of CD8+ T Cells in Brain with Low-Intensity Focused Ultrasound-Guided Sequential Delivery of CXCL10, IL-2, and aPD-L1 for Glioblastoma Immunotherapy

Abstract

Improving clinical immunotherapy for glioblastoma (GBM) relies on addressing the immunosuppressive tumor microenvironment (TME). Enhancing CD8⁺ T cell infiltration and preventing its exhaustion holds promise for effective GBM immunotherapy. Here, a low-intensity focused ultrasound (LIFU)-guided sequential delivery strategy is developed to enhance CD8⁺ T cells infiltration and activity in the GBM region. The sequential delivery of CXC chemokine ligand 10 (CXCL10) to recruit CD8⁺ T cells and interleukin-2 (IL-2) to reduce their exhaustion is termed an "open-source throttling" strategy. Consequently, up to 3.39-fold of CD8⁺ T cells are observed with LIFU-guided sequential delivery of CXCL10, IL-2, and anti-programmed cell death 1 ligand 1 (aPD-L1), compared to the free aPD-L1 group. The immune checkpoint inhibitors (ICIs) therapeutic efficacy is substantially enhanced by the reversed immunosuppressive TME due to the expansion of CD8⁺ T cells, resulting in the elimination of tumor, prolonged survival time, and long-term immune memory establishment in orthotopic GBM mice. Overall, LIFU-guided sequential cytokine and ICIs delivery offers an "open-source throttling" strategy of CD8⁺ T cells, which may present a promising strategy for brain-tumor immunotherapy.

Keywords: CXCL10; IL‐2; T‐cell exhaustion; glioblastoma; immune checkpoint inhibitors; immunosuppressive microenvironment; low‐frequency focused ultrasound.