Retrospective analysis of ribociclib and letrozole as first-line therapy in patients with hormone receptor (HR) positive metastatic breast cancer (MBC) within a managed access program (MAP) in Turkey.

e13055 Background: The combination of ribociclib with ET significantly increased progression free survival (PFS) and OS compared with ET in first line treatment of HR positive HER2 negative MBC. We aimed to evaluate the efficacy and safety of ribociclib and letrozole within Turkish MAP in order to present clinical outcome with the real-world use of ribociclib, outside of clinical trial setting. Methods: Turkish MAP enabled access to ribociclib in combination with letrozole as first-line therapy for MBC patients with HR positive and Her-2 negative tumors. Adequate bone marrow reserve, a normal QTc interval, normal renal and liver functions were required for eligibility. Patients received 600 mg ribociclib once daily for 3 wks followed by 1wk off. A retrospective chart review of patient demographics, clinical and treatment characteristics have been performed. Results: Between July and November 2017, 178 patients were included from 47 institutions in Turkey. We report the results of first 101 patients analyzed. The median age was 53 years (33–81 years) and median follow up was 16 months. Forty-six patients had de novo disease, 78% patients were postmenopausal, 22% had ovarian function suppression. Thirty-six % patients had adjuvant chemotherapy, 49% received adjuvant ET. Forty % had visceral disease. Thirty patients had grade 3 neutropenia, 3 patients had febrile neutropenia, 5 patients have grade 2-3 elevation of liver function tests. There was no QT prolongation. Dose reduction to 400 mg was required for 16 patients. Four patients discontinued ribociclib due to toxicity, 22 patients due to progression, one patient refused treatment. Twelve patients had complete remission as their best response. Median PFS was 24.12 months (95%CI 22.2-26.2). None of the clinical and pathologic factors were significantly associated with prolonged PFS. Conclusions: The efficacy and toxicity of first-line ribociclib and letrozole within Turkish MAP is similar to the results from randomized clinical studies for patients with HR positive, Her-2 negative MBC.