Ribociclib plus letrozole in patients with hormone receptor-positive, HER2-negative advanced breast cancer with no prior endocrine therapy: subgroup safety analysis from the phase 3b CompLEEment-1 trial
Article Category: Research Article
Published Online: May 17, 2022
Page range: 238 - 247
Received: Feb 25, 2022
Accepted: Apr 08, 2022
DOI: https://doi.org/10.2478/raon-2022-0020
© 2022 Simona Borstnar, Marketa Palacova, Aleksandra Łacko, Constanta Timcheva, Einav Nili Gal-Yam, Konstantinos Papazisis, Juraj Beniak, Pavol Kudela, Gábor Rubovszky, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Background
The CDK4/6 inhibitor, ribociclib in combination with endocrine therapy significantly improved progression-free survival in the first line setting in post-menopausal patients with HR+/HER2− advanced breast cancer (ABC) in a pivotal phase 3, placebo-controlled trial (MONALEESA-2) and demonstrated superior overall survival in premenopausal patients with HR+/HER2− ABC (MONALEESA-7). The multinational, phase 3b, CompLEEment-1 trial, which assessed the safety and efficacy of ribociclib plus letrozole in a broader population of patients who have not received prior endocrine therapy for advanced disease, is the largest phase 3 clinical trial to date to evaluate the safety and efficacy of a CDK4/6 inhibitor. We report a subanalysis of data from patients (N = 339) enrolled in the central and south European countries of the SERCE (Southern Europe, RUC, Central Europe) cluster of CompLEEment-1.
Patients and methods
Men and women of any menopausal status with HR+/HER2− ABC received once-daily oral ribociclib 600 mg (3-weeks on/1-week-off), plus letrozole 2.5 mg continuously. Men/premenopausal women also received a GnRH-agonist. The primary outcome was the number of patients with adverse events (AEs) over a timeframe of approximately 36 months. Time-to-progression, overall response rate, and clinical benefit rate were also measured.
Results
Safety results in the SERCE subgroup were consistent with those in the pivotal clinical trials of ribociclib in combination with endocrine therapy. Treatment-related AEs leading to dose adjustments/interruption occurred in 63.1% of patients but led to treatment discontinuation in only 10.6%. The most common treatment-related AEs of grade ≥ 3 were neutropenia and transaminase elevations. There were no fatal treatment-related events.
Conclusions
These findings from the SERCE subgroup support the safety and manageable tolerability of ribociclib in a broad range of patients with HR+/HER2− ABC more representative of patients in real-world clinical practice.