ARNEO: A Randomized Phase II Trial of Neoadjuvant Degarelix with or Without Apalutamide Prior to Radical Prostatectomy for High-risk Prostate Cancer

Background: High-risk prostate cancer (PCa) patients have a high risk of biochemical recurrence and metastatic progression following radical prostatectomy (RP).Objective: To determine the efficacy of neoadjuvant degarelix plus apalutamide before RP compared with degarelix with a matching placebo. Design, setting, and participants: ARNEO was a randomized, placebo-controlled, phase II neoadjuvant trial before RP performed between March 2019 and April 2021. Eligible patients had high-risk PCa and were amenable to RP.Intervention: Patients were randomly assigned at a 1:1 ratio to degarelix (240-80-80 mg) + apalutamide (240 mg/d) versus degarelix + matching placebo for 3 mo followed by RP. Prior to and following neoadjuvant treatment, pelvic 18F-PSMA-1007 positron emission tomography (PET)/magnetic resonance imaging (MRI) was performed.Outcome measurements and statistical analysis: The primary endpoint was the difference in proportions of patients with minimal residual disease (MRD; = residual cancer burden (RCB) <0.25 cm3 at final pathology). Secondary endpoints included differences in prostate-specific antigen responses, pathological staging, and change in TNM stage on prostate-specific membrane antigen (PSMA) PET/MRI following hormonal treatment. Biomarkers (immunohistochemical staining on prostate biopsy [PTEN, ERG, Ki67, P53, GR, and PSMA] and PSMA PET/MRI-derived characteristics) associated with pathological response (MRD and RCB) were explored. Results and limitations: Patients were randomized to neoadjuvant degarelix + apaluta mide (n = 45) or degarelix + matching placebo (n = 44) for 12 wk and underwent RP. Patients in the degarelix + apalutamide arm achieved a significantly higher rate of MRD than those in the control arm (38% vs 9.1%; relative risk [95% confidence inter-val] = 4.2 [1.5-11], p = 0.002). Patients with PTEN loss in baseline prostate biopsy attained significantly less MRD (11% vs 43%, p = 0.002) and had a higher RCB at final pathology (1.6 vs 0.40 cm3, p < 0.0001) than patients without PTEN loss. Following neoadjuvant hormonal therapy, PSMA PET-estimated tumor volumes (1.2 vs 2.5 ml, p = 0.01) and maximum standardized uptake value (SUVmax; 4.3 vs 5.7, p = 0.007) were lower in patients with MRD than in patients without MRD. PSMA PET-estimated volume and PSMA PET SUVmax following neoadjuvant treatment correlated significantly with RCB at final pathology (both p < 0.001).Conclusions: In high-risk PCa patients, neoadjuvant degarelix plus apalutamide prior to RP results in a significantly improved pathological response (MRD and RCB) compared with degarelix alone. Our trial results provide a solid hypothesis-generating basis for neoadjuvant phase 3 trials, which are powered to detect differences in long-term onco-logical outcome following neoadjuvant androgen receptor signaling inhibitor therapy.Patient summary: In this study, we looked at the difference in pathological responses in high-risk prostate cancer patients treated with degarelix plus apalutamide or degarelix plus matching placebo prior to radical prostatectomy. We demonstrated that patients treated with degarelix plus apalutamide achieved a significantly better tumor response than patients treated with degarelix plus matching placebo. Long-term follow-up is required to determine whether improved pathological outcome translates into better oncological outcomes.(c) 2022 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Automated summary

In this study, it was demonstrated that the combination of degarelix and apalutamide prior to radical prostatectomy significantly improved tumor response in high-risk prostate cancer patients compared to degarelix alone. These trial results provide a solid hypothesis-generating basis for neoadjuvant phase 3 trials to detect differences in long-term oncological outcomes.