They found that cancer-testis antigen 45 (CT45) is an independent prognostic factor associated with double prolongation of disease-free survival in high-grade serous ovarian cancer (HGSOC); CT45 thus acts as a novel prognostic indicator of HGSOC, a regulatory site of sensitivity to chemotherapy, and a target of immunotherapy. This evidence concerns the gene CT45A1 and ovarian serous adenocarcinoma.