PDCD1 and breast cancer: Management of BC has undergone rapid development in the last decade, and immune therapy has been a breakthrough in the landscape of BC treatment, with the FDA approval of all five checkpoint blockers targeting programmed cell death protein 1, such as pembrolizumab and nivolumab, or programmed cell death ligand 1, including atezolizumab, avelumab, and durvalumab, along with the introduction of the first antibody–drug conjugate, enfortumab vedotin, transforming the landscape of BC treatment [4, 5, 6, 7].