Abstract 664P
Background
Immediate antiandrogen therapy after radical prostatectomy (RP) reduces risk of recurrence in patients with positive lymph nodes. Its use in negative lymph nodes is debated. We report data from the PRIORITI study (NCT01753297) on the efficacy of triptorelin, a gonadotrophin-releasing hormone agonist, in patients with high-risk prostate cancer who had undergone RP but had no evidence of residual disease.
Methods
This phase 4, open-label, randomized, controlled trial included patients in China and Russia with prostate adenocarcinoma. Eligibility criteria are summarized in the table. Patients were randomized to triptorelin (11.25 mg at baseline, 3 and 6 months) or active surveillance (AS). The primary outcome was Biochemical Relapse-Free Survival (BRFS), defined as time from randomization to Biochemical Relapse (BR; increased prostate specific antigen level > 0.2 ng/mL, confirmed by a second measurement 4‒6 weeks later). Efficacy was assessed in the Intent-to-Treat (ITT) Population. A log-rank test (two-sided) was used to compare BRFS between groups. The Kaplan–Meier method was used to estimate the Q1 BFRS in each group. Patients with BR and/or clinical disease progression were monitored for 36 months, those without continued to be followed every 3 months. The study ended when 61 BRs were observed.
Results
The ITT population comprised 226 patients with a mean (standard deviation) age of 65.3 (6.4) years. Baseline characteristics relating to RP were similar in both groups. The median BRFS was not reached. The Q1 BRFS (95% CI) was 39.1 months (29.9, not estimated) with triptorelin versus 30.0 months (18.6, 42.1) with AS (p=0.159). No specific safety issues were observed. Table: 664P
Eligibility criteria
| Key inclusion criteria |
| Aged ≥ 18 years Histo-pathologically confirmed adenocarcinoma of the prostate Undergone RP ≤ 8 weeks prior to randomization Post-RP PSA levels ≤ 0.2 ng/mL at 6 weeks High risk of disease progression, defined as a: • Gleason score ≥ 8 on prostatectomy specimen, and/orGleason score ≥ 8 on prostatectomy specimen, and/or • pre-RP PSA level ≥ 20 ng/mL, and/or • primary tumour stage 3a ECOG performance status of 0 to 1 |
| Key exclusion criteria |
| Evidence of lymph node or distant metastasis Positive surgical margins Evidence of other malignant disease not treated with a curative intent Surgical castration |
PSA, prostate specific antigen; RP, radical prostatectomy.
Conclusions
In high-risk patients without evidence of residual disease following RP, BRFS was longer with triptorelin than with AS, but the difference was not statistically significant.
Clinical trial identification
NCT01753297.
Editorial acknowledgement
Dr David Gothard of Oxford PharmaGenesis, Oxford, UK, provided medical writing and editorial support, which was sponsored by Ipsen.
Legal entity responsible for the study
Ipsen.
Funding
Ipsen.
Disclosure
V. Matveev: Honoraria (self): Ipsen; Honoraria (self), Advisory/Consultancy: Bayer; Honoraria (self), Advisory/Consultancy: MSD; Honoraria (self): AstraZeneca; Honoraria (self), Advisory/Consultancy: BMS; Honoraria (self), Advisory/Consultancy: Janssen. A. Houchard: Full/Part-time employment: Ipsen. P. Cabri: Full/Part-time employment: Ipsen. All other authors have declared no conflicts of interest.