First-line talazoparib plus enzalutamide versus placebo plus enzalutamide in men with metastatic castration-resistant prostate cancer and homologous recombination repair gene alterations: patient-reported outcomes from the randomised, double-blind, placebo-controlled, phase 3 TALAPRO-2 trial.

BACKGROUND: In the phase 3 TALAPRO-2 trial, talazoparib plus enzalutamide significantly improved radiographic progression-free survival compared with placebo plus enzalutamide in men with metastatic castration-resistant prostate cancer harbouring alterations in genes involved in homologous recombination repair (HRR). We aimed to assess patient-reported outcomes in patients with HRR-deficient metastatic castration-resistant prostate cancer in TALAPRO-2. METHODS: TALAPRO-2 is a randomised, double-blind, placebo-controlled, phase 3 trial conducted at 223 hospitals, cancer centres, and medical centres in 26 countries worldwide. Eligible participants were male patients aged 18 years or older (≥20 years in Japan) who were receiving ongoing androgen deprivation therapy, had asymptomatic or mildly symptomatic metastatic castration-resistant prostate cancer, an Eastern Cooperative Oncology Group performance status of 0 or 1, and had not received previous life-prolonging systemic therapy for castration-resistant prostate cancer or metastatic castration-resistant prostate cancer. Patients with HRR gene alterations were randomly assigned (1:1) using a centralised interactive web response system and a permuted block size of 4 to oral talazoparib 0·5 mg once daily or placebo, plus oral enzalutamide 160 mg once daily, stratified by previous second-generation androgen receptor pathway inhibitor (abiraterone or orteronel) or docetaxel (yes vs no) in the castration-sensitive setting. The sponsor, patients, and investigators were masked to allocation of talazoparib or placebo; enzalutamide was open-label. The primary endpoint was radiographic progression-free survival by blinded independent central review and has been reported previously. Patient-reported outcomes were assessed as secondary outcomes in the patient-reported outcomes population, which comprised patients from the intention-to-treat population with a baseline patient-reported outcome assessment and at least one post-baseline patient-reported outcome assessment. Patient-reported outcomes included time to definitive deterioration in global health status/quality of life (GHS/QoL) per European Organisation for Research and Treatment of Cancer (EORTC) Core Quality of Life Questionnaire (QLQ-C30) and prostate cancer-specific urinary symptoms per EORTC Quality of Life Questionnaire-Prostate (QLQ-PR25), and time to deterioration in pain symptoms per Brief Pain Inventory-Short Form (BPI-SF). Mean change from baseline in GHS/QoL, overall cancer and prostate cancer-specific functioning and symptoms (per EORTC QLQ-C30 and QLQ-PR25), in pain symptoms per BPI-SF, and in general health status per EQ-5D-5L were also patient-reported secondary outcomes. This study is registered with ClinicalTrials.gov, NCT03395197, and is ongoing. FINDINGS: Between Dec 18, 2018, and Jan 20, 2022, 399 patients with HRR-deficient metastatic castration-resistant prostate cancer were enrolled and randomly assigned, of whom 197 assigned to talazoparib plus enzalutamide and 197 assigned to placebo plus enzalutamide were included in the patient-reported outcome population. Median follow-up was 22·2 months (IQR 13·8-27·7) in the talazoparib plus enzalutamide group and 20·2 months (13·5-26·6) for the placebo plus enzalutamide group. Median time to definitive deterioration of GHS/QoL was longer in the talazoparib plus enzalutamide group (27·1 months [95% CI 21·2-non-estimable]) than in the placebo plus enzalutamide group (19·3 months [16·6-23·0]; hazard ratio [HR] 0·69 [95% CI 0·49-0·97]; two-sided p=0·032). Median time to definitive deterioration in urinary symptoms was also longer in the talazoparib plus enzalutamide group (non-estimable [95% CI 32·2-non-estimable]) than in the placebo plus enzalutamide group (30·2 months [24·6-non-estimable; HR 0·56 [0·34-0·93]; two-sided p=0·022). Median time to deterioration in pain symptoms was non-estimable for both treatment groups (HR 0·58 [0·33-1·01]; two-sided p=0·051). Changes fro