PROTEUS: A randomized, double-blind, placebo (PBO)-controlled, phase 3 trial of apalutamide (APA) plus androgen deprivation therapy (ADT) versus PBO plus ADT prior to radical prostatectomy (RP) in patients with localized high-risk or locally advanced prostate cancer (PC).

Abstract

TPS5100 Background: Patients (pts) with localized high-risk PC experience disease progression rates of approximately 50% after RP (Kane et al. J Urol. 2007). With the approval of next-generation androgen receptor inhibitors, neoadjuvant studies have shown that 6 months of androgen blockade may improve local disease control at the time of RP (McKay et al. Prostate Cancer Prostatic Dis. 2017; Taplin et al. JCO. 2014). The purpose of this study is to determine if treatment with APA plus ADT before and after RP in pts with localized high-risk or locally advanced PC results in an improvement in pathologic complete response (pCR) rate and metastasis-free survival (MFS) compared with PBO plus ADT. Methods: This international multicenter trial is enrolling pts with localized high-risk or locally advanced PC who are candidates for RP. Eligibility criteria: Any Gleason score (GS) ≥ 4 + 3 with ≥ 6 positive systematic biopsies (SB); any GS ≥ 4 + 3 with ≥ 3 SB and prostate-specific antigen (PSA) ≥ 20 ng/mL; GS ≥ 9 in ≥ 1 SB or targeted biopsies (TB); or ≥ 2 SB or TB with continuous GS ≥ 8, each with ≥ 80% involvement. Stratification: GS (7 or ≥ 8), cN0 or N1, and region (North America, Europe, or rest of world). Randomization: 1:1 to APA (240 mg) plus ADT (LHRHa) or PBO plus ADT. Pts will receive 6 treatment cycles, followed by RP, followed by an additional 6 cycles. Dual primary end points: pCR rate (to be assessed by blinded independent central pathology review) and MFS (to be assessed by blinded independent central radiology review [BICR]). Secondary end points: PSA-free survival and progression-free survival. Imaging with CT or MRI and bone scan will be conducted at baseline and then every 6 months following biochemical failure until documented distant metastasis by BICR, or death. Approximately 1500 pts will be enrolled globally over 3.0 years in 240 sites in 19 countries. An independent data monitoring committee is commissioned to review trial data. Clinical trial information: NCT03767244.