Improvement of radiotherapy with an ozone-carried liposome nano-system for synergizing cancer immune checkpoint blockade

Radiotherapy is a compatible regimen for synergizing immune checkpoint blockade therapy by promoting immunogenic cell death. To improve the efficiency of irradiation-induced neoantigen generation, we designed and developed an ozone-carrying liposome perfluorodecalin (PFD) nano-system (O3_PFD@Liposome) which promoted ozone solubility by 18.4-fold compared to that in water solution. The O3_PFD@Liposome particle remarkably improved the irradiation-induced hydroxyl radical generation. Evaluation of sub-cellular biodistribution indicated that the nano-system could be efficiently internalized by tumor cells. Upon released inside tumor cells, ozone generated reactive oxygen species under the stimulation of X-ray irradiation. Notably, O3_PFD@Liposome significantly prompted anti-tumor efficacy of radiotherapy without inducing severe adverse effects. The combo regimen with radiotherapy and ozone potently enhanced the infiltration of lymphocytes in the tumor microenvironment by inducing immunogenic cell death, releasing neoantigens, and relieving hypoxia symptom. Consequently, the combination of ozone-fueled irradiation and PD-1 blockade synergistically inhibited the growth of primary and abscopal tumors.