Scavenging Reactive Oxygen Species by Cerium Oxide Nanoparticles Prevents Death in a Peripheral T Cell Lymphoma Preclinical Mouse Model

Cancer cell survival and proliferation are correlated with increased metabolic activity and consequent oxidative stress, driving metabolic shifts that interfere with the immune response to malignant cells. This is the case of high-energy-demanding angioimmunoblastic T cell lymphoma (AITL), a highly aggressive cancer with poor survival rates, where malignant CD4+ PD-1^high T cells show increased mitochondrial activity and Reactive oxygen species (ROS) accumulation. Here, we report that administration of ROS scavenging cerium oxide (CeO₂) nanoparticles in an AITL preclinical mouse model leads to their preferential accumulation in the spleen, where the CD4+ PD-1^high T cells driving malignancy were significantly reduced. This was accompanied by activation of previously exhausted cytotoxic CD8+ T cells, restoring their potent antitumor function. As a result, survival rates dramatically increase with no observed toxicity to healthy cells or tissues. Overall, it highlights the correlation between increased energy demand, increased mitochondrial mass, increased PD-1 expression, increased ROS production, and immune suppression and how this vicious loop can be stopped by scavenging ROS.