Targeting defective DNA repair in prostate cancer

Prostate cancer is the second leading cause of cancer death in men. Characterization of the genomic landscape of prostate cancer has demonstrated frequent aberrations in DNA repair pathways, identifiable in up to 25% patients with metastatic disease, which may sensitize to novel therapies, including PARP inhibitors and immunotherapy. Here, we summarize the current clinical landscape and future horizons for targeting defective DNA repair pathways in PC.

Several clinical trials have demonstrated efficacy of different PARP inhibitors in metastatic castration-resistant prostate cancer (mCRPC), most pronounced in those with BRCA mutations. The PROfound trial is the first positive phase 3 biomarker-selected trial to demonstrate improved outcomes with a targeted treatment, Olaparib, in mCRPC. Whilst the Keynote-199 trial failed to demonstrate efficacy of immune-checkpoint inhibitor pembrolizumab in unselected mCRPC patients, there was evidence of response in those harbouring DNA repair defects.

These landmark trials represent a significant advance towards personalization of PC therapy. However, resistance remains inevitable and there is a lack of reliable predictive biomarkers to select patients for treatment. Characterization of resistance mechanisms, and validation of novel biomarkers is critical to maximize clinical benefit and inform novel treatment combinations to improve outcomes.