Whilst pan-histological clinical studies have highlighted a significant treatment benefit for patients with ARID1A-deficient tumours when treated with (PD-1)/PD-L1 immunotherapy [25], their response rate specifically in OCCC-specific trials, such as PEACOCC (NCT03425565) testing pembrolizumab in patients with advanced gynaecological clear cell cancer, has not been reported to date. This evidence concerns the gene CD274 and neoplasm.