Genomic Biomarker for Prostate Cancer Focal Therapy: Post Hoc Assessment of a Phase II Clinical Trial.

Purpose: A biomarker to help predict outcomes after prostate cancer (PCa) focal therapy would be of considerable interest. We sought to assess the association between treatment failure after focal therapy and the Decipher score, a tumor-based genomic classifier (GC).

Materials and methods: We performed a post hoc analysis of a single-center phase II trial (ClinicalTrials.gov identifier: NCT03503643) in which patients with unilateral grade group (GG) 2-4 PCa (n = 108) underwent hemigland cryoablation of the prostate (2017-2021; n = 108). Pretreatment biopsy tissue was subjected to transcriptomic profiling to generate GC scores. The primary outcome was the association between GC-low (<0.45) versus GC-high (≥0.45) and in-field recurrence (GG ≥2) on magnetic resonance imaging-guided biopsy 6 months post-treatment, evaluated using multivariable logistic regression.

Results: In the GC-high group (n = 37), treatment failure occurred in 17 patients (46%). In the GC-low group (n = 71), treatment failure occurred in 15 patients (21%). These differences were statistically significant (odds ratio [OR], 2.61 [95% CI, 1.05 to 6.51]; P = .04). Differences at 18 months were also significant (76% v 44%; OR, 3.58 [95% CI, 1.37 to 9.36], P = .009).

Conclusion: In patients with PCa otherwise suitable for management with focal therapy, a high GC score (≥0.45) was independently associated with treatment failure. A GC score derived from diagnostic biopsy can be used to help predict focal therapy outcomes.