Injectable Bioresponsive Gel Depot for Enhanced Immune Checkpoint Blockade.

Although cancer immunotherapy based on immune checkpoint inhibitors holds great promise toward many types of cancers, several challenges still remain, associated with low objective response of patient rate as well as systemic side effects. Here, a combination immunotherapy strategy is developed based on a thermogelling reactive oxygen species (ROS)-responsive polypeptide gel for sustained release of anti-programmed cell death-ligand 1 antibody and dextro-1-methyl tryptophan, inhibitor of indoleamine-2,3-dioxygenase with leveraging the ROS level in the tumor microenvironment. This bioresponsive gel depot can effectively reduce the local ROS level and facilitate release of immunotherapeutics, which leads to enhanced anti-melanoma efficacy in vivo.