PRIORITI: Phase 4 study of triptorelin or active surveillance in high-risk prostate cancer

Abstract

Aim: To evaluate the efficacy and safety of triptorelin after radical prostatectomy (RP) in patients with negative lymph nodes.

Methods: PRIORITI (NCT01753297) was a prospective, open-label, randomized, controlled, phase 4 study conducted in China and Russia. Patients with high-risk (Gleason score ≥ 8 and/or pre-RP prostate-specific antigen [PSA] ≥ 20 ng/mL and/or primary tumor stage 3a) prostate adenocarcinoma without evidence of lymph node or distant metastases were randomized to receive triptorelin 11.25 mg at baseline (≤ 8 weeks after RP) and at 3 and 6 months, or active surveillance. The primary endpoint was biochemical relapse-free survival (BRFS), defined as the time from randomization to biochemical relapse (BR; increased PSA > 0.2 ng/mL). Patients were monitored every 3 months for at least 36 months; the study ended when 61 BRs were observed.

Results: The intention-to-treat population comprised 226 patients (mean [standard deviation] age, 65.3 [6.4] years), of whom 109 and 117 were randomized to triptorelin or surveillance, respectively. The median BRFS was not reached. The 25th percentile time to BRFS (95% confidence interval) was 39.1 (29.9-not estimated) months with triptorelin and 30.0 (18.6-42.1) months with surveillance (p = 0.16). There was evidence of a lower risk of BR with triptorelin versus surveillance but this was not statistically significant at the 5% level (p = 0.10). Chemical castration was maintained at month 9 in 93.9% of patients who had received triptorelin. Overall, triptorelin was well tolerated and had an acceptable safety profile.

Conclusion: BRFS was observed to be longer with triptorelin than surveillance, but the difference was not statistically significant.

Keywords: biochemical relapse‐free survival; prostate cancer; prostate‐specific antigen; radical prostatectomy; triptorelin.