57MO First-line (1L) Ribociclib (RIB) + Endocrine Therapy (ET) Vs Combination Chemotherapy (combo CT) in HR+/HER2− Advanced Breast Cancer (ABC): A Post Hoc Analysis of Asian and Non-Asian Patients (pts) from the Phase II RIGHT Choice Trial

RIGHT Choice reported a statistically significant median progression-free survival (mPFS) benefit of ≈1 y with RIB + ET vs combo CT (24.0 vs 12.3 mo; HR, 0.54; P=.0007) in pre- or perimenopausal pts with HR+/HER2− ABC. We report outcomes in Asian and non-Asian pts from this trial. Pre- or perimenopausal pts with HR+/HER2− ABC and no prior systemic therapy for ABC were randomized to RIB + ET or investigator’s choice of combo CT (Table). Pts had ABC for which combo CT was clinically indicated by physician’s judgment (symptomatic visceral metastases, rapid disease progression/impending visceral compromise, or markedly symptomatic non-visceral disease). Pt characteristics between arms were balanced in the Asian (n=118) and non-Asian (n=104) subgroups. Similar characteristics were seen in Asian and non-Asian pts, with some differences in BMI (median, 23.7 vs 26.3 kg/m2) as well as the proportion with symptomatic non-visceral disease (7.6% vs 21.2%) and physician-assessed visceral crisis (69.5% vs 32.7%). The PFS benefit with RIB + ET vs CT was 15.0 mo (mPFS, 25.2 vs 10.2 mo; HR, 0.43) in Asian pts and 8.3 mo (21.1 vs 12.8 mo; HR, 0.75) in non-Asian pts. In both groups, the median time to treatment (tx) failure (mTTF) was longer and the 3-mo tx failure rate (TFR) was lower with RIB + ET vs CT. In Asian pts, the overall response rate (ORR) was higher with RIB + ET than CT, with similar clinical benefit rate (CBR) and median time to response (mTTR) in both arms. In non-Asian pts, the ORR and CBR were similar in both arms, with longer mTTR for RIB + ET vs CT. The safety profile in the subgroups was consistent with that of the overall pt population. This post hoc analysis confirmed a clinically meaningful PFS benefit with 1L RIB + ET vs combo CT in pre- or perimenopausal Asian and non-Asian pts with HR+/HER2− ABC.Table: 57MOSub- groupArmnmPFS (95% CI), moHR (95% CI)mTTF (95% CI), moHR (95% CI)3-mo TFR (95% CI), %ORR, %aCBR, %amTTR (95% CI), moaAsianRIB + ET6025.2 (17.1-NR)0.43 (0.25-0.74)19.5 (12.7-NR)0.42 (0.26-0.68)10.0 (3.8-20.5)71.781.74.6 (3.0-6.6)CTb5810.2 (8.3-18.4)8.5 (6.7-13.6)19.0 (9.9-31.4)56.974.14.7 (2.7-NR)Non-AsianRIB + ET5221.1 (10.2-NR)0.75 (0.42-1.32)18.6 (10.2-24.0)0.48 (0.29-0.80)13.5 (5.6-25.8)57.778.87.4 (4.4-NR)CTb5212.8 (8.8-18.4)8.8 (6.6-12.3)25.0 (14.0-38.9)63.571.22.9 (1.4-4.5)NR, not reached. a Unconfirmed; b Docetaxel + capecitabine, paclitaxel + gemcitabine, or capecitabine + vinorelbine. Open table in a new tab