Impact of Somatic DNA Repair Mutations on the Clinical Outcomes of Bone Metastases from Castration-Resistant Prostate Cancer

Up to 80% of castration-resistant prostate cancer (CRPC) patients develop bone metastases during the natural history of disease and about 25% harbor mutations in DNA damage repair (DDR) genes. This retrospective observational study evaluated the prevalence of DDR alterations in CRPC patients and their effect on the clinical outcomes associated with bone metastases. The mutational status of CRPC patients was analyzed per FoundationOne(®) analysis in tissue biopsy or, when it was not possible, in liquid biopsy performed at the onset of metastatic CRPC (mCRPC). The impact of DDR gene mutations on bone-related efficacy endpoints was evaluated at the time of mCRPC diagnoses. In total, 121 mCRPC patients with bone metastases were included: 38 patients had mutations in at least one DDR gene, the remaining 83 ones had a non-mutated DDR status. DDR mutated status was associated with bone metastases volume (p = 0.006), but did not affect SRE (skeletal-related events) incidence and time to SRE onset. Liquid and tissue biopsies were both available for 61 patients with no statistically significant difference in terms of incidence and type of molecular DDR alterations. Mutated DDR status was associated with higher bone metastasic volume, although a not detrimental effect on the other bone-related efficacy endpoints was observed.