There is a plethora of research on multiple combination therapies with anti-CTLA-4 antibodies + anti-PD-1/PD-L1 antibodies + other agents, and researchers have combined anti-CTLA-4 antibodies with multiple other agents for breast cancer treatment without the use of anti-PD-1/PD-L1 antibodies. Here, PDCD1 is linked to breast cancer.