RIBECCA: A phase IIIb, multi-center, open label study for women with estrogen receptor positive locally advanced or metastatic breast cancer treated with ribociclib (LEE011) in combination with letrozole—Results of the first interim analysis.

1051Background: RIBECCA is a national, multi-center, open-label, single-arm phase IIIb trial assessing the efficacy and safety of ribociclib in combination with letrozole in a patient population similar to the populations of MONALEESA-2, -3 and -7. Here we present the results of the first preplanned interim analysis. Methods: Main inclusion criteria allow enrollment of men or women with metastatic or locally advanced breast cancer not amenable to curative treatment by surgery or radiotherapy, and histological or cytological confirmation of ER+, HER2- breast cancer, irrespective of their menopausal status. The primary objective is to assess the clinical benefit rate (CBR) after 6 months, secondary objectives include progression free survival (PFS), overall survival (OS), safety and changes in quality of life. Results: The cut-off date for this first interim analysis was 12 months after the enrollment of the first patient (24-Oct-2017). Here we describe the baseline characteristics and safety data of patien...