In addition, a variety of treatments are still in clinical trials, including IL-8/CXCR inhibitors, breast cancer vaccines, and lysing viruses, angiogenesis inhibitors, and inhibitors of cyclin-dependent kinase 4 (CDK4) and CDK6, in combination with PD-1/PD-L1 inhibitors [64,65]. Here, PDCD1 is linked to breast cancer.