Patient-reported Outcomes (pros) with Talazoparib (TALA) Plus Enzalutamide (ENZA) Vs. Placebo (PBO) Plus ENZA in Men with Metastatic Castration-Resistant Prostate Cancer (mcrpc): Subgroup Analysis of Patients with Novel Hormonal Therapy (NHT) Pretreatment in the TALAPRO-2 Study.

116 Background: In TALAPRO-2 (NCT03395197), TALA +ENZA vs PBO + ENZA demonstrated significant improvement in radiographic progression-free survival, a manageable adverse event (AE) profile, and a delay in time to definitive clinical meaningful deterioration in global health status (GHS)/quality of life (QoL) overall and across all pre-specified subgroups. This post hoc analysis evaluated PROs in patients with prior NHT treatment. Methods: PROs were assessed on day 1 and scheduled visits (every 4 weeks until week 53 then every 8 weeks) until radiographic progression using the EORTC QLQ-C30 and its prostate cancer module, QLQ-PR25. PRO analyses, performed in NHT-pretreated/ patients for GHS/QoL functional and symptom scales, included on treatment comparison of overall change from baseline (per longitudinal repeated measures mixed-effects model). Results: Of the 805 men randomized and treated, 49 patients were included in this subgroup analysis (TALA + ENZA n= 22, PBO + ENZA n= 27). A statistically significant and clinically meaningful estimated overall change from baseline favored TALA + ENZA in physical functioning (20.5 [95% confidence interval {CI}: 8.8, 32.2]; P=0.0007), role functioning (20.4 [95% CI 4.8, 35.9]; P=0.0103), pain (32.9 [95% CI 50.3, 15.5]; P=0.0002), and constipation (12.5 [24.4, 0.6]; P=0.0399). No significant differences disfavoring TALA + ENZA were observed. Conclusions: In these subgroup analyses of NHT pretreated patients, significant differences in PROs favoring TALA + ENZA were observed. Results should be interpreted with caution given the small sample sizes and exploratory nature of this analysis. Clinical trial information: NCT03395197 .