Thus, our data demonstrate that the USP7 inhibitor, P5091, negatively modulates the stability and the transcriptional activity of ARFL and of its V7 truncated variant; moreover, our data indicates that the USP7 inhibitor P5091 reduces levels and function of CCDC6, favouring the sensitivity to PARP inhibitors in hormone-sensitive and most importantly, in castration resistant prostate cancer cells (Figure 4A, 4B). Here, PARP1 is linked to Familial prostate cancer.