Abstract 649P
Background
Prostate cancer is described as a hormonal dependent cancer so that androgen-deprivation therapy (ADT) is the major strategy for patients with prostate cancer. Abiraterone acetate is a CYP17 inhibitor which can suppress androgen biosynthesis. This phase III study aims to further evaluate the safety and efficacy of abiraterone acetate in patients with metastatic castration-resistant prostate cancer (mCRPC) who had not received chemotherapy.
Methods
In this double-blind study, men aged ≥18 years who have previously received ADT, with histologically or cytologically confirmed mCRPC were eligible; documented metastases and had PSA progression. 258 patients were randomized 2:1 abiraterone acetate was administered orally (1000 mg, qd) plus prednisone (5 mg, bid) or placebo plus prednisone till disease progression, death or intolerant toxicity. The primary endpoint was time to PSA progression (TTPP) and the secondary endpoints included PSA response rate, quality of life, objective response rate (ORR), time to pain progression and overall survival (OS).
Results
Patients were enrolled from October 2015 to May 2019, 178 patients received abiraterone acetate and 84 patients received placebo. The median follow-up of abiraterone and placebo was 22.8 and 21.5 months, respectively. The median time to PSA progression was 11.5 months (95%CI, 10.12-14.0) with abiraterone acetate compared with 5.65 months (95%CI, 4.60-8.34) with placebo (hazard ratio, 0.57; 95% CI, 0.40 to 0.80; P=0.0011). The PSA response rate was 63.79% in abiraterone acetate and 32.14% in placebo (P<0.0001). And the median OS was 23.95 months (95%CI, 17.18-NR) in abiraterone acetate. Grade 3 or 4 AEs were reported in 18.97% of patients in the abiraterone group versus 19.05% of patients in the placebo group; Most of the occurring AEs included upper respiratory tract infection (13.22%), hypertension (12.64%), nasopharyngitis (12.07%), cough (9.77%), hypokalemia (8.62%), and diarrhea (8.62%). Neither unexpected safety signals.
Conclusions
Abiraterone acetate produces PSA response rate and TTPP benefits, showed a promising efficacy with a favorable toxicity profile for patients with mCRPC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.