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

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.