BRCA1 and neoplasm: As we had detected enhanced expression of PD-L1 in response to in vitro olaparib therapy, in the second animal study, mice harbouring ID8 Trp53−/− Brca1−/− or ID8 Trp53−/− Brca2−/− tumours were treated with either olaparib or anti-PD-L1 monotherapies, or a combination of both drugs, using the treatment regimen summarized in Supplementary Figure S 1.