We previously showed that expression of programmed cell death ligand-1 (PD-L1), an immune-checkpoint molecule, was associated with patients’ poor prognoses in ovarian cancer.6,7 Anti-PD-L1 antibody proved to be effective against recurrent ovarian cancer cases with platinum resistance.8 However, PD-1/PD-L1 blockade exhibited durable response to only a small portion of platinum-resistant ovarian cancer cases. Here, CD274 is linked to ovarian carcinoma.