Summary Background HSD3B1(1245A>C) has been mechanistically linked to castration-resistant prostate cancer by encoding an altered enzyme that augments dihydrotestosterone synthesis. We hypothesized that men inheriting the HSD3B1(1245C) allele would exhibit resistance to androgen deprivation therapy (ADT). Methods We determined HSD3B1 genotype retrospectively in men treated with ADT for post-prostatectomy biochemical failure and correlated genotype with long-term clinical outcomes. Patients who received postoperative adjuvant or salvage radiotherapy were eligible, provided they had residual active disease as reflected by continued increase in their PSA after treatment. We analyzed progression-free survival (PFS; primary endpoint), distant metastasis-free survival (DMFS), and overall survival (OS) according to HSD3B1 genotype. Multivariable analyses were performed to assess the independent predictive value of HSD3B1 genotype on outcomes. Results were externally validated in two additional cohorts, including a second post-prostatectomy biochemical failure cohort as well as a metastatic cohort. There was no age limit for eligibility in the primary or validation cohorts. Findings The study included 443 patients: 118 in the primary cohort, 137 in the post-prostatectomy validation cohort, and 188 in the metastatic validation cohort. In the primary study cohort, median PFS diminished as a function of the number of variant alleles inherited: 6.6 years in homozygous wild-type men (95% CI, 3.8 to not reached); 4.1 years in heterozygotes (95% CI, 3.0 to 5.5); and 2.5 years in homozygous variant men (95% CI, 0.7 to not reached); P=0.011. Median DMFS likewise decreased according to the number of variant alleles inherited: 9.1 years (95% CI, 7.4 to not reached); 6.8 years (95% CI, 4.3 to 7.4); and 3.6 years (95% CI, 1.0 to 7.3), respectively; P=0.014. Finally, OS diminished with the number of variant alleles inherited: 5-year and 10-year OS 82% (95% CI, 69 to 94) and 55% (95% CI, 35 to 75) in homozygous wild-type men; 74% (95% CI, 62 to 85) and 35% (95% CI, 21 to 49) in heterozygotes; and 58% (95% CI, 30 to 86) and 0% in homozygous variant men; P=0.0064. On multivariable analysis, the hazard ratio (HR) for progression was 1.6 for men with at least one variant allele (95% CI, 1.0 to 2.7; P=0.074), which compared favorably with Gleason score (HR 1.3 for Gleason score 8–10 vs. 6–7; 95% CI 0.8 to 2.0; P=0.31), though neither factor reached statistical significance with the small sample size. The impact of homozygous variant genotype on metastasis (HR 2.8; 95% CI, 1.1 to 6.7; P=0.025) and death (HR 3.5; 95% CI 1.3 to 9.5; P=0.013) was maintained on multivariable analysis. Findings in the external cohorts independently validated the impact of HSD3B1(1245C) on outcomes. Interpretation Inheritance of the HSD3B1(1245C) allele that enhances dihydrotestosterone synthesis is associated with prostate cancer resistance to ADT. Our findings nominate HSD3B1 as a powerful genetic biomarker capable of distinguishing men who are a priori ...

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The adrenal-restrictive HSD3B1(1245A) allele limits extragonadal dihydrotestosterone synthesis, whereas the adrenal-permissive HSD3B1(1245C) allele augments extragonadal dihydrotestosterone synthesis. Retrospective studies have suggested an association between the adrenal-permissive allele, the frequency of which is highest in white men, and early development of castration-resistant prostate cancer (CRPC).OBJECTIVE To examine the association between the adrenal-permissive HSD3B1(1245C) allele and early development of CRPC using prospective data. DESIGN, SETTING, AND PARTICIPANTSThe E3805 Chemohormonal Therapy vs Androgen Ablation Randomized Trial for Extensive Disease in Prostate Cancer (CHAARTED) was a large, multicenter, phase 3 trial of castration with or without docetaxel treatment in men with newly diagnosed metastatic prostate cancer. From July 28, 2006, through December 31, 2012, 790 patients underwent randomization, of whom 527 had available DNA samples. In this study, the HSD3B1 germline genotype was retrospectively determined in 475 white men treated in E3805 CHAARTED, and clinical outcomes were analyzed by genotype. Data analysis was performed from July 28, 2006, to October 17, 2018.INTERVENTIONS Men were randomized to castration plus docetaxel, 75 mg/m 2 , every 3 weeks for 6 cycles or castration alone.MAIN OUTCOMES AND MEASURES Two-year freedom from CRPC and 5-year overall survival, with results stratified by disease volume. Patients were combined across study arms according to genotype to assess the overall outcome associated with genotype. Secondary analyses by treatment arm evaluated whether the docetaxel outcome varied with genotype. RESULTSOf 475 white men with DNA samples, 270 patients (56.8%) inherited the adrenal-permissive genotype (Ն1 HSD3B1[1245C] allele). Mean (SD) age was 63 (8.7) years.Freedom from CRPC at 2 years was diminished in men with low-volume disease with the adrenal-permissive vs adrenal-restrictive genotype: 51.0% (95% CI, 40.9%-61.2%) vs 70.5% (95% CI, 60.0%-80.9%) (P = .01). Overall survival at 5 years was also worse in men with low-volume disease with the adrenal-permissive genotype: 57.5% (95% CI, 47.4%-67.7%) vs 70.8% (95% CI, 60.3%-81.3%) (P = .03). Hazard ratios were 1.89 (95% CI, 1.13-3.14; P = .02) for CRPC and 1.74 (95% CI, 1.01-3.00; P = .045) for death. There was no association between genotype and outcomes in men with high-volume disease. There was no interaction between genotype and benefit from docetaxel.CONCLUSIONS AND RELEVANCE Inheritance of the adrenal-permissive HSD3B1 genotype is associated with earlier castration resistance and shorter overall survival in men with low-volume metastatic prostate cancer and may help identify men more likely to benefit from escalated androgen receptor axis inhibition beyond gonadal testosterone suppression.