Real-world safety and effectiveness of ribociclib in Korean patients with HR+/HER2-locally advanced or metastatic breast cancer

초록

Background Ribociclib (RIB) is a cyclin-dependent kinase 4/6 inhibitor approved in South Korea on 30 October 2019 for the treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced or metastatic breast cancer. We aimed to assess the safety and effectiveness of RIB in the real-world setting through post-marketing surveillance (PMS) analysis. Methods This is an interim analysis of the PMS results. Per protocol, follow-up period of 24 weeks from initiation of RIB is recommended for safety and effectiveness analysis. Safety is evaluated based on incidence of adverse events (AE), including serious adverse events (SAE) and adverse drug reactions (ADR). Effectiveness is evaluated based on overall response rate at 24 weeks. Results Of the 380 patients who initiated RIB (October 2019 – October 2023), 363 patients and 324 patients were eligible for safety and effectiveness analysis, respectively. 294 of 380 patients (77.4%) completed 24 weeks of RIB treatment, while 86 patients (22.6%) discontinued treatment mainly due to progression of disease (n=37/86, 43.0%). Median duration of treatment was 127.0 days, and mean daily dose of RIB was 565.8 ± 67.5 mg/day. Of safety analysis set, 78 patients (21.5%) experienced ≥1 RIB dose reduction with median time to first dose reduction of 1.6 months. Total of 945 AEs were reported in 305 patients (84.0%). 59 SAEs were reported from 42 patients (11.6%), and 602 events were considered ADRs (69.4%). Most frequent AEs were neutropenia (46.6%), followed by nausea (13.2%) and rash (13.0%). AEs grade ≥3 were reported in 44.6% of patients. Most common grade ≥3 AE was neutropenia (35.8%). Overall response at 24 weeks after treatment initiation was observed in 114 patients (35.2%). Complete response and partial response were achieved in 5 patients (1.5%) and 109 patients (33.6%), respectively. Stable disease was observed in 172 patients (53.1%). Conclusions This is the first analysis evaluating the safety and effectiveness of RIB in Korean patients in real-world setting. These interim data support the clinical benefits of RIB. Observed safety profile is consistent with findings from MONALEESA trials, and no unexpected safety signal was observed with RIB.