Australian real-world outcomes of ribociclib and aromatase inhibitor in hormone receptor (HR) positive, HER2 negative metastatic breast cancer (MBC): Results from Kisqali Access Registry for Metastatic breast cancer in Australia (KARMA) collected alongside a medicine access program.

Abstract

e13018 Background: International guidelines recommend a combination of CDK4/6 inhibitor and endocrine therapy (ET) as first line treatment for HR+, HER2- MBC. Results from MONALEESA-2 demonstrate improved progression free survival (PFS) with ribociclib (CDK4/6 inhibitor) and ET as compared to ET alone. Prior to Australia’s Pharmaceutical Benefits Scheme funding, ̃800 patients participated in the ribociclib Medicine Access Program (MAP) from May 2017 to June 2018. Methods: KARMA is a secondary data use, non-interventional study of Australian patients who received first line treatment with ribociclib and aromatase inhibitor (AI), obtained via a MAP, for HR+, HER2- MBC. The aim was to capture comprehensive patient and treatment data to reflect real world practice and outcomes. Direct comparisons were made with the ribociclib/letrozole cohort in MONALEESA-2 given that the eligibility criteria were similar for both studies. Results: Data from 160 patients at 17 sites was analysed with a median follow up of 36.5 months. Baseline characteristics are shown in the table. 63 of 160 (39%) patients remain on ribociclib/AI at time of analysis. 58% of patients had at least 1 dose reduction, with the majority (77%) requiring only a single dose reduction. The most common reasons for dose reductions were neutropenia (68%) and abnormal liver enzymes (17%). 16 of 160 (10%) discontinued treatment due to toxicity, including 1 patient with QTc prolongation > 600ms. There were no deaths due to toxicity. Median duration of treatment and PFS were 24.5 (95% CI 17.8-33.3) and 36.3 months (95% CI 29.9- NR) respectively, compared to 20.2 and 25.3 months in MONALEESA-2. Landmark PFS was 76% at 12 months, 67% at 18 months and 64% at 24 months. Conclusions: This is the first real world study of ribociclib and AI developed alongside a MAP. The combination treatment was well tolerated with similar rates of dose reductions (58% in both) and treatment discontinuation due to toxicity (10% vs 8%) when compared to MONALEESA-2. This real-world cohort achieved a superior PFS, potentially explained in part by a younger population with more favourable baseline disease characteristics, including fewer disease sites and higher rates of bone only metastases. It is encouraging to see drug tolerability and efficacy replicated in real world patients.[Table: see text]