CTLA4 and breast carcinoma: Current and emerging therapies in HER-2-positive breast cancer not only target HER-2 receptors but also extend to HER3, programmed-death ligand (PD-L1), cytotoxic T-lymphocyte-associated protein-4 (CTLA-4), natural killer group 2A (NKG-2A), AKT, PI3K, estrogen receptors, and cyclin-dependent kinases 4/6 in triple-positive tumors [45].