First-line (1L) ribociclib (RIB) + endocrine therapy (ET) vs combination chemotherapy (combo CT) in clinically aggressive hormone receptor (HR)+/HER2− advanced breast cancer (ABC): A subgroup analysis of patients (pts) with or without liver metastases (mets) from RIGHT Choice.

Abstract

1069 Background: The phase II RIGHT Choice trial reported a statistically significant progression-free survival (PFS) benefit at the primary prespecified analysis and a 9-month (mo) benefit at the final analysis with 1L RIB + ET over combo CT in pts with clinically aggressive HR+/HER2– ABC. As liver mets in ABC indicate a worse prognosis, an analysis by liver mets status was performed (data cutoff: May 10 th , 2023). Methods: Pre- and perimenopausal women (N = 222) with no prior systemic therapy for clinically aggressive HR+/HER2− ABC were randomized 1:1 to receive RIB + letrozole or anastrozole + goserelin or physician's choice of combo CT. Enrolled pts had ABC for which combo CT was clinically indicated by physician’s judgment. Results: In total, 107 (RIB + ET, n = 54; combo CT, n = 53) and 115 (RIB + ET, n = 58; combo CT, n = 57) pts presented with or without liver mets, respectively. Pts with liver mets had PFS of 18.3 vs 12.7 mo and median time to treatment failure (mTTF) of 13.2 vs 8.3 mo with RIB + ET vs combo CT, respectively (Table). A clinical benefit rate (CBR) of 77.8% vs 67.9%, overall response rate (ORR) of 64.8% vs 60.4%, and median time to response (mTTR) of 6.4 vs 3.0 mo were seen in the RIB vs CT arm, respectively. Pts without liver mets had PFS of 25.2 vs 15.4 mo and mTTF of 24.0 vs 10.1 mo in the RIB vs CT arm, respectively, and similar CBR, ORR, and TTR regardless of treatment (tx). No new safety signals were observed in pts with liver mets. A numerically longer median time to deterioration (mTTD) in FACT-B total score was seen with RIB + ET vs combo CT in pts with and without liver mets. Conclusions: This analysis from RIGHT Choice showed similar clinically meaningful efficacy and quality-of-life benefits and no new safety signals for RIB + ET vs combo CT between pts with and without liver mets. These results support the 1L use of RIB + ET in pts with clinically aggressive HR+/HER2– ABC even in the presence of liver mets. Clinical trial information: NCT03839823 . Liver mets Tx arm n mPFS,mo(95% CI) HR(95% CI) mTTF,mo(95% CI) HR(95% CI) CBR a ,%(95% CI) ORR a ,%(95% CI) mTTR a ,mo(95% CI) HR(95% CI) mTTD (FACT-B total score) b ,mo HR(95% CI) Yes RIB + ET 54 18.3(10.3-24.0) 0.68(0.42-1.11) 13.2(10.2-21.2) 0.60(0.39-0.92) 77.8(64.4-88.0) 64.8(50.6-77.3) 6.4(4.6-23.9) 0.68(0.42-1.10) 37.7 0.68(0.34-1.34) Combo CT c 53 12.7(7.5-21.0) 8.3(5.3-12.8) 67.9(53.7-80.1) 60.4(46.0-73.5) 3.0(2.6-6.7) 18.4 No RIB + ET 58 25.2(18.6-NE) 0.57(0.34-0.93) 24.0(16.4-32.2) 0.44(0.29-0.69) 84.5(72.6-92.7) 67.2(53.7-79.0) 4.6(2.8-10.2) 0.81(0.52-1.28) NE 0.59(0.29-1.21) Combo CT c 57 15.4(8.8-20.0) 10.1(7.8-13.6) 80.7(68.1-90.0) 63.2(49.3-75.6) 4.5(1.4-8.2) 37.1 NE, not evaluable. a Without confirmation; b ≥7 point decrease; c docetaxel + capecitabine, paclitaxel + gemcitabine, or capecitabine + vinorelbine.