The exploration of LNPs, which carry double‐stranded siRNA for the purpose of knocking down checkpoint inhibitors such as anti‐PD‐L1, indoleamine 2,3‐dioxygenase 1 (IDO), and transcription factor forkhead box P3 (FOXP3), among others, is being investigated for the treatment of cancer, as well as for in vitro engineered DC vaccines.111. Here, IDO1 is linked to cancer.