Abiraterone Without Ongoing GnRH Holds Testosterone Down and Delivers 27-Month PFS in Metastatic Prostate Cancer

Abiraterone, a CYP17 inhibitor that is approved for prostate cancer, + prednisone was given to 31 men with metastatic prostate cancer after stopping their GnRH analogue in this single-arm Phase II study (NCT03565835). The median progression-free survival was 119 weeks (~27 mo) while overall survival was not reached at 4.4 years’ follow-up. Testosterone remained suppressed; luteinizing hormone rose to > 1.2 IU/L after a median 21 weeks. No patients discontinued treatment due to AEs. Common grade 1-2 side effects included fatigue (13%), hot flashes (16%), and hypokalemia (6%). Only one patient experienced grade 3 fatigue.