PDCD1 and ovarian serous adenocarcinoma: Strickland et al. (2016) demonstrated that BRCA 1/2-mutated high grade serous ovarian cancer had remarkably elevated CD3+ and CD8+tumor-infiltrating lymphocytes and elevated expression levels of PD-1. PD-L1 in the tumor-linked immune cells contrasted with that in homologous recombination proficient tumors. Another study also showed that the presence of intraepithelial CD8+ T-cells was linked to a mutation or loss of expression of BRCA1 (Clarke et al., 2009).