Whole genome sequencing of 378 prostate cancer metastases reveals tissue selectivity for mismatch deficiency with potential therapeutic implications.

backgroundSurvival of patients with metastatic castration-resistant prostate cancer (mCRPC) depends on the site of metastatic dissemination.

methodsPatients with mCRPC were prospectively included in the CPCT-02 metastatic site biopsy study. We evaluated whole genome sequencing (WGS) of 378 mCRPC metastases to understand the genetic traits that affect metastatic site distribution.

resultsOur findings revealed that RB1, PIK3CA, JAK1, RNF43, and TP53 mutations are the most frequent genetic determinants associated with site selectivity for metastatic outgrowth. Furthermore, we explored mutations in the non-coding genome and found that androgen receptor (AR) chromatin binding sites implicated in metastatic prostate cancer differ in mutation frequencies between metastatic sites, converging on pathways that impact DNA repair. Notably, liver and visceral metastases have a higher tumor mutational load (TML) than bone and lymph node metastases, independent of genetic traits associated with neuroendocrine differentiation. We found that TML is strongly associated with DNA mismatch repair (MMR)-deficiency features in these organs.

conclusionsOur results revealed gene mutations that are significantly associated with metastatic site selectivity and that frequencies of non-coding mutations at AR chromatin binding sites differ between metastatic sites. Immunotherapeutics are thus far unsuccessful in unselected mCRPC patients. We found a higher TML in liver and visceral metastases compared to bone and lymph node metastases. As immunotherapeutics response is associated with mutational burden, these findings may assist in selecting mCRPC patients for immunotherapy treatment based on organs affected by metastatic disease. TRIAL REGISTRATION NUMBER: NCT01855477.