This is a multicenter, randomized, open label, phase III study comparing the efficacy and safety of apatulamide combined with concomitant prostate-bed salvage radiotherapy (SRT) and androgen deprivation therapy (ADT) versus concomitant prostate-bed SRT and ADT in high-risk postprostatectomy biochemically relapsed prostate cancer patients.

The purpose of the CARLHA-2 study is to determine if the combination of apalutamide with 6 months of LHRH agonists and radiotherapy results in an improvement of progression-free survival (PFS) in comparison to the combination of 6 months of LHRH agonists with radiotherapy in high-risk postprostatectomy biochemically relapsed prostate cancer patients. Radical prostatectomy must have been done at least 6 months before inclusion and is not part of this study. Patients after radical prostatectomy and biochemical relapse will be randomized in a 1:1 ratio to receive either 6 months of LHRH agonists + SRT or 6 months of LHRH agonists + SRT + 6 months of apalutamide. The stratification variables include Gleason score, prostate-specific antigen (PSA), negative resection margins, extension to seminal vesicle(s), and PSA doubling time.