Efficacy, safety, and patient-reported outcomes across young to older age groups of patients with HR+/HER2- advanced breast cancer treated with ribociclib plus endocrine therapy in the randomized MONALEESA-2, -3, and -7 trials.

Background: Ribociclib + endocrine therapy (ET) showed significant progression-free survival (PFS) and overall survival (OS) benefits in the MONALEESA trials in patients with HR+ /HER2 - advanced breast cancer (ABC). We report efficacy, safety, and patient-reported outcomes (PROs) across age groups, including older patients, in these trials.

Methods: Data from the MONALEESA-2, -3, and -7 trials for pre- and postmenopausal patients receiving first-line treatment for ABC were pooled and analyzed by age (<65y, 65-74y, and ≥75y). PFS, OS, time to first chemotherapy (TTC), and time to definitive deterioration (TTD) in PROs were evaluated using Kaplan-Meier methods; a Cox regression model stratified by study and liver/lung metastasis was used for hazard ratios.

Results: Among 1229 patients included, 63 % were < 65y, 27 % were 65-74y, and 10 % were ≥ 75y. Baseline characteristics were generally well balanced. Regardless of patient age, ribociclib+ET showed a consistent PFS and OS benefit and delayed TTC. With ribociclib+ET, the most common first subsequent treatment was ET. Safety results were consistent with those in the overall trial population; no new signals were identified. Rates of discontinuation due to AEs with ribociclib+ET were numerically higher in patients ≥ 75y. Among patients who discontinued treatment due to AEs, the percentage without prior dose reduction was higher in those ≥ 75y. A PRO benefit with ribociclib+ET was observed across all age groups for pain and fatigue scores.

Conclusions: This analysis demonstrated that ribociclib+ET is an effective and well-tolerated treatment for patients of all age groups with HR+ /HER2 - ABC, including older patients. (MONALEESA-2, NCT01958021; MONALEESA-3, NCT02422615; MONALEESA-7, NCT02278120).