HSD3B1 (1245A>C) germline variant and clinical outcomes in metastatic castration-resistant prostate cancer patients treated with abiraterone and enzalutamide: results from two prospective studies

•The HSD3B1 homozygous variant genotype CC was associated with shorter time to progression on abiraterone and enzalutamide.•The effect of the CC genotype on time to progression was the same for abiraterone and enzalutamide.•Patients who present the CC genotype were less likely to achieve a prostate-specific antigen response (≥50% decline).•The CC genotype was not confirmed as an independent prognosis factor and it may not be a suitable stand-alone biomarker in metastatic castration-resistant prostate cancer.