Real-World Outcomes of DNA Damage Repair Altered Metastatic Castration-Resistant Prostate Cancer: Insights from FFPE-Based Genomic Profiling.

Germline and somatic variants in DNA Damage Repair (DDR) genes are found in approximately one-fourth of patients with metastatic prostate cancer (PC). However, their precise prognostic role and predictive impact on standard therapies remain controversial. This retrospective, single-center study evaluated the prevalence of germline/somatic DDR aberrations in 287 eligible patients with metastatic prostate cancer (mPC), treated between 2017 and 2022. Clinical characteristics and treatment outcomes (PFS and OS) for chemotherapy (taxanes) or next-generation hormonal therapies (NHT) were compared between DDR-mutated (DDRmut) and wild-type (DDRwt) cohorts. Sixty-three patients (21.9%) were DDRmut, with BRCA2 (12.5%), ATM (3.1%), and BRCA1 (1.39%) being the most common alterations. A family history of breast, ovarian, or prostate cancer strongly predicted DDRmut status (47.0% vs. 14.0%, p = 0.0001). Tissue samples remained evaluable for sequencing up to 180 months from collection. Overall baseline characteristics were similar between cohorts, and BRCA1/2- and ATM-mutated patients treated with first-line taxanes for mCRPC presented with non significantly highermedian OS compared to DDRwt patients (70 vs. 36 months; p = 0.30). On the contrary, the DDRmut subgroup showed a trend toward shorter PFS (12 vs. 18 months; p = 0.04) when treated with first-line NHT. No significant differences were observed with third-line Cabazitaxel. Formalin-fixed paraffin-embedded (FFPE) prostate tissue is highly reliable for DDR, possibly integrating novel liquid biopsy approaches for DDR evaluation. In a real-world setting, BRCA1/2 and ATM variants identify a distinct molecular subgroup that derives preferential survival benefit from first-line taxanes over standard hormonal intensification.