205P Pooled exploratory analysis of survival in patients (pts) with HR+/HER2- advanced breast cancer (ABC) and visceral metastases (mets) treated with ribociclib (RIB) + endocrine therapy (ET) in the MONALEESA (ML) trials

Abstract

RIB + ET demonstrated statistically significant progression-free survival (PFS) and overall survival (OS) benefits in the ML-2, -3, and -7 trials in pts with HR+/HER2− ABC. The presence of visceral mets indicates a worse prognosis, with a particularly poor survival observed in pts with liver mets. Here we report a pooled survival analysis of the ML-2, -3, and -7 trials in pts with visceral mets, including those with liver mets. In ML-2, postmenopausal pts were randomized 1:1 to receive first-line (1L) RIB or placebo (PBO) with letrozole. In ML-3, postmenopausal pts were randomized 2:1 to receive RIB or PBO with fulvestrant in the 1L or second-line (2L) setting. In ML-7, premenopausal pts were randomized 1:1 to receive 1L RIB or PBO and goserelin with nonsteroidal aromatase inhibitor (NSAI)/tamoxifen (only pts in the NSAI arm were included in this analysis). A significant PFS and OS benefit was observed with RIB in pts with visceral mets (Table), among which were pts with liver mets or ≥3 met disease sites across the pooled population of 1L/2L. This significant benefit persisted in the 1L subgroup, including in the subgroups of pts with a worse prognosis, such as those with liver mets or ≥3 met sites who achieved a median OS of ≈4-5 y with RIB. No new safety signals, including liver enzyme elevations, even in pts with baseline liver mets, were observed. This large, pooled analysis of the ML trials confirms the consistent survival benefit of RIB + ET in pts with visceral mets who historically have a poor prognosis. This analysis also demonstrates the substantial benefit of RIB in those with poorer outcomes within the visceral mets subgroup, ie, pts with liver mets and those with multiple met disease sites, especially in the 1L population.Table: 205PVisceral metsLiver metsVisceral mets and ≥3 metsET+Overall1LOverall1LOverall1LRIBPBORIBPBORIBPBORIBPBORIBPBORIBPBOn640484395319276222140116334263253195mPFS, mo22.112.729.614.713.45.716.79.821.311.024.814.5HR (95% CI), P0.61 (0.53-0.70), <.00010.57 (0.48-0.68), <.0010.52 (0.42-0.65), <.00010.55 (0.41-0.74), <.00010.55 (0.46-0.67), <.00010.59 (0.47-0.74), <.001mOS, mo49.046.562.752.139.635.444.238.149.040.457.749.3HR (95% CI), P0.81(0.69-0.94), .0030.79(0.65-0.97), .0230.71(0.57-0.89), .0020.77(0.55-1.07), .120.73 (0.59-0.90), .0020.81 (0.63-1.03), .09 Open table in a new tab