Key clinical point: In addition to switching endocrine therapy (ET), continuing the cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) with ribociclib therapy vs placebo demonstrated progression-free survival (PFS) benefits in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2−) metastatic breast cancer (BC) who had progressed on previous ET and CDK4/6i.
Major finding: At a median follow-up of 18.2 months, a significant improvement in PFS was observed in the ET+ribociclib+CDK4/6i vs ET+placebo group (hazard ratio 0.57; P = .006). ET+ribociclib+CDK4/6i demonstrated a manageable safety profile.
Study details: Findings are from the phase 2 MAINTAIN trial including 119 patients with HR+/HER2− metastatic BC who progressed on ET and CDK4/6i and were randomly assigned to receive a different ET with ribociclib plus CDK4/6i or placebo.
Disclosures: This study was supported by Novartis Pharmaceuticals and other sources. The authors declared no conflicts of interest.
Source: Kalinsky K et al. Randomized phase II trial of endocrine therapy with or without ribociclib after progression on cyclin-dependent kinase 4/6 inhibition in hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer: MAINTAIN trial. J Clin Oncol. 2023 (May 19). doi: 10.1200/JCO.22.02392