CLO20-039: Patient (pt)-Reported Outcomes (PRO) in Patients With HER2-Negative Locally Advanced/Metastatic Breast Cancer (LA/mBC) and a Germline BRCA1/2 Mutation (gBRCA1/2 mut) Receiving Talazoparib vs. Physician’s Choice of Chemotherapy (PCT): A Focus on EMBRACA Racial Subgroups

Background: Key subgroup analyses of EMBRACA (NCT01945775) demonstrated improvements in progression-free survival for talazoparib vs PCT in white and non-white pts with HER2-negative g BRCA1/2 mut LA/mBC. We present post hoc analyses evaluating PRO in these racial subgroups. Methods: PRO was assessed at baseline, start of treatment cycle (every 3 wks), and end of treatment using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) and its breast cancer module, QLQ-BR23. Higher scores indicate better functioning/global health status (GHS)/quality of life (QoL) or worse symptom severity. PRO analyses, performed separately in white/non-white pts for GHS/QoL functional and symptom scales, included comparison of overall change from baseline (per longitudinal repeated measures mixed-effects model) and time to definitive clinically meaningful deterioration (TTD; per survival analysis methods) using a Cox proportional hazards model and stratified log-rank test. Results: Baseline PRO scores in the evaluable population were similar between the talazoparib (white/non-white, n=173/89) and PCT (white/non-white, n=84/30) arms. A statistically significant estimated overall change from baseline in GHS/QoL favored talazoparib vs PCT for white (7.4 [95% confidence interval {CI}: 2.6, 12.2]; P =0.003) and non-white (10.1 [95%CI: 3.7, 16.5]; P =0.002) pts. A statistically significant estimated overall change from baseline in pt reported pain symptoms favored talazoparib vs PCT for white ( P <0.001) and non-white ( P =0.02) pts. A statistically significant delay in TTD favoring talazoparib vs PCT was observed in GHS/QoL for both white (median [m]: 21.1 vs 6.3 mos, hazard ratio [HR]=0.38 [95% CI: 0.24, 0.59]; P <0.001]) and non-white (m: [not reached] vs 10.4 mos, HR=0.38 [95% CI: 0.17, 0.83]; P =0.01) pts. A delay in TTD favoring talazoparib was observed in pain symptoms for both white (m: 22.7 vs 10.3 mos, HR=0.29, P <0.001) and non-white (m: 23.0 vs 7.5 mos, HR=0.63, P =0.22) pts. Conclusions: In pts with HER2-negative g BRCA1/2 mut LA/mBC, talozaparib vs PCT resulted in significantly better change from baseline and delayed TTD in GHS/QoL and pt reported pain symptoms in white pts; similar results were observed in non-white pts. Future real-world PRO studies across different racial subgroups are warranted.