CD274 and breast cancer: Another approach used in a different study was the injection of a reactive oxygen species (ROS)-degradable hydrogel that encapsulated gemcitabine and anti-PD-L1 antibody into the mammary fat tissue of a murine model of low-immunogenic breast cancer (4T1); the ROS-induced degradation of the hydrogel led to the release of gemcitabine, causing tumor cell death and creating an immunogenic microenvironment, which was accompanied by a delayed release of anti-PD-L1, resulting in delayed tumor growth and improved survival.