CD4 and neoplasm: Examination of specific T-cell subsets, including T cells (CD3, CD4, CD8), B cells (CD20) and checkpoints (PD-1, PD-L1, see below), to date, has shown no difference between BRCA1mut and BRCA2mut tumours, and between BRCAmut and BRCAwt tumours, albeit with the latter studies almost universally performed in triple-negative breast cancers [120,128].