Real‐world progression‐free survival and overall survival in patients with <scp>HR</scp> ⁺ / <scp>HER2</scp> ⁻ advanced breast cancer treated in first‐line with ribociclib, endocrine monotherapy or chemotherapy: Results from the observational <scp>RIBANNA</scp> study

Cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) combined with endocrine therapy are the preferred choice for first-line treatment of patients with HR⁺/HER2^- locally advanced/metastatic breast cancer (aBC). The CDK4/6i ribociclib in combination with an aromatase inhibitor (AI) or fulvestrant (FUL) has demonstrated significant progression-free survival (PFS) and overall survival (OS) benefits for pre- and postmenopausal aBC patients who were enrolled in the three pivotal MONALEESA trials. Following the initial approval of ribociclib in 2017, the non-interventional RIBANNA study was initiated to evaluate the effectiveness and safety of ribociclib plus AI/FUL therapy among patients with aBC in a real-world setting. Two additional treatment cohorts (endocrine monotherapy [ET] and chemotherapy [CT]) were included to extend the knowledge about current aBC treatments. A total of 2567 patients were enrolled in 279 study centers, of whom 1852 were treated with ribociclib+AI/FUL, 183 were treated with ET, and 139 were treated with CT, who were available for effectiveness analyses. Median PFS (mPFS) and median OS (mOS) on first-line treatment with ribociclib+AI/FUL were 35.0 and 76.0 months, respectively. Adjustment for differences in demographic and baseline characteristics resulted in a longer mPFS on ribociclib+AI/FUL (34.7 months) compared to ET (26.4 months) or CT (19.2 months). Adverse events (AEs) on ribociclib were consistent with those seen in the pivotal trials, and no new safety signals were observed. The RIBANNA study confirmed the PFS and OS benefit seen in the MONALEESA trials. Together with the safety data, this large real-world dataset supports the favorable risk/benefit profile of ribociclib in large scale patient populations.