Thus, the expression of PD-1 in intraepithelial CD8 TILs has been associated with a favourable prognosis in high-grade serous ovarian carcinomas.15 Prior studies have shown that NY-ESO-1-specific CD8+ TILs from OC patients expresses PD-1.16 In addition, ovarian tumours with deficient homologous recombination (HR) have a higher predicted neoantigen (NeoAg) load and infiltrating CD8 T cells in these tumours have increased PD-1 expression.17 Here, PDCD1 is linked to ovarian serous carcinoma.