402P First-line Ribociclib (RIB) + Endocrine Therapy (ET) Vs Combination Chemotherapy (combo CT) in Aggressive HR+/HER2− Advanced Breast Cancer (ABC): A Subgroup Analysis of Patients (pts) with or Without Visceral Crisis from the Phase II RIGHT Choice Study

RIGHT Choice showed a statistically significant median progression-free survival (mPFS) benefit of ≈1 yr with first-line RIB + ET vs combo CT (HR, 0.54; P=.0007) in pts with aggressive HR+/HER2− ABC. As visceral crisis indicates need for a more rapidly efficacious treatment (tx), a subgroup analysis by visceral crisis status was performed. Pre/perimenopausal pts (N=222) with no prior systemic therapy for aggressive HR+/HER2− ABC were randomized 1:1 to RIB + letrozole/anastrozole + goserelin or physician's choice of combo CT. Visceral crisis assessment was based on physician’s judgment, following ABC 3 guidelines available at the time. Overall, 116 (RIB + ET, n=61; CT, n=55) and 106 (RIB + ET, n=51; CT, n=55) pts presented with or without visceral crisis, respectively. In pts with visceral crisis, a mPFS of 12.9 mo was seen with RIB + ET vs 11.2 mo with combo CT (HR, 0.87). While in these pts the overall response rate (ORR) numerically favored RIB + ET, the time to treatment failure (TTF) and clinical benefit rate (CBR) were similar in both tx arms (Table). In pts with no visceral crisis, a mPFS benefit was seen with RIB + ET vs combo CT (24.0 vs 12.7 mo; HR, 0.34); also, TTF and CBR favored RIB + ET over combo CT. RIB + ET was associated with lower rates of symptomatic adverse events than combo CT in both groups. These interim results are based on the 12 Apr 2022 data cutoff; final results will be shown at ESMO 2023. This analysis shows similar PFS and TTF outcomes but greater ORR with RIB + ET vs combo CT in pts with physician-assessed visceral crisis. Clinically meaningful tx benefit with RIB + ET over combo CT was seen in pts with aggressive disease not classified as visceral crisis. These findings support RIB + ET over combo CT in pts with aggressive ABC even in the presence of visceral crisis.Table: 402PVisceral CrisisTx ArmnmPFS (95% CI), moHR (95% CI)mTTF, moHR (95% CI)ORR, %*CBR, %*YesRIB + ET6112.9 (9.9-25.2)0.87 (0.51-1.47)10.30.68 (0.43-1.08)72.177.0Combo CT†5511.2 (8.4-21.0)10.256.470.9NoRIB + ET5124.0 (21.1-NR‡)0.34 (0.18-0.63)24.00.29 (0.17-0.51)56.984.3Combo CT†5512.7 (8.3-17.5)8.563.674.5*Without image confirmation; †Docetaxel + capecitabine, paclitaxel + gemcitabine, or capecitabine + vinorelbine; ‡Not reached. Open table in a new tab