A Study of Androgen Annihilation in High-Risk Biochemically Relapsed Prostate Cancer

Patients will be stratified by PSA doubling time (\< 3 months vs. 3-9 months) and randomized in 1:1:1 fashion to one of three treatment arms: (1) Control arm consisting of LHRH analogue monotherapy (degarelix or leuprolide), (2) Experimental arm consisting of apalutamide in combination with LHRH analogue, and (3) Experimental arm consisting of apalutamide, abiraterone acetate + prednisone, and LHRH analogue. Patients will be treated for a maximum duration of 52 weeks and then enter follow up phase until the time of PSA progression, development of metastasis, or patient withdrawal from study, whichever occurs first. Patients with PSA progression will be followed long term until the development of castration resistance, first metastasis, and death. The primary endpoint of the study is PSA progression-free survival in the intent-to-treat patient population. PSA progression during the 52-week treatment period is defined as a rising PSA confirmed on repeat measurement, and at least 25% and 2 ng/mL above nadir or baseline, whichever is lower. PSA progression during follow up defined as PSA \> 0.2 ng/mL confirmed by repeat measurement at least 2 weeks later. Secondary study endpoints include PSA progression-free survival in testosterone-evaluable population, 36-month PSA progression-free survival rate in both intent-to-treat and testosterone-evaluable populations, time to testosterone recovery, time to castration resistance, metastasis-free survival, quality of life, and safety. Each experimental arm will be compared against the control arm in pair-wise fashion. The study is not powered to detect differences in primary or secondary endpoints between the two experimental arms.