Promotion of Triple Negative Breast Cancer Immunotherapy by Combining Bioactive Radicals with Immune Checkpoint Blockade.

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Although immunotherapy has revolutionized clinical cancer treatment, the efficacy is limited due to the lack of tumor-associated antigens (TAAs) and the presence of compensatory immune checkpoints. To overcome the deficiency, a nano-system loaded with ozone and CD47 inhibitor RRx-001 is designed and synthesized. Upon irradiation, reactive oxygen species (ROS) generated from ozone reacts with nitric oxide (NO) metabolized from RRx-001 to form reactive nitrogen species (RNS), which presents a much stronger cell-killing ability than ROS. Molecular mechanism studies further reveal that RNS induce extensive immunogenic cell death (ICD). The released TAAs promote infiltration of cytotoxic T lymphocytes, which provides the basis for immune checkpoint blockade (ICB) therapy. Meanwhile, RRx-001 carried by the nanoparticles and the produced radicals repolarize M2-type tumor-associated macrophages (TAMs) into the anti-tumor M1-type, consequently reversing the immunosuppressive tumor microenvironment (TME). In a xenograft triple-negative breast cancer (TNBC) animal model, O3-001@lipo (liposome enwrapping O3 and RRx-001) plus irradiation shows a significant anti-tumor efficacy by improving cytotoxic lymphocyte infiltration and regulating immunosuppressive TME. In summary, the O3-001@lipo nano-system triggered by irradiation potently improves the efficacy of immunotherapy by introducing strong cytotoxic RNS, which not only enriches the toolbox of ICD inducer but also provides a strategy of treatment for immune deficient tumor. STATEMENT OF SIGNIFICANCE: Significance 1: The significance of the work with respect to the existing literature This study introduces a nano-system that leverages ozone and RRx-001 in the presence of X-ray irradiation to generate reactive nitrogen species, enhancing immunogenic cell death and promoting T-lymphocyte infiltration in triple-negative breast cancer, addressing a significant unmet need in the field. Significance 2: The scientific impact and interest to our readership The scientific contribution is the development of a clinically translatable nano-system that not only induces ICD but also reshapes the tumor microenvironment, which is expected to have a profound impact on the readership in pharmaceutics, material science, and nano-bio interaction, particularly for those interested in advanced immune therapy approaches.