This clinical trial is focused on studying treatments for advanced hormone receptor-positive/HER2-negative/HER2-Enriched breast cancer. The study will compare two medications: ribociclib (also known as LEE011) and palbociclib, both of which are used in combination with endocrine therapy. The purpose of the study is to see which treatment is more effective in delaying the progression of the disease.
Participants in the study will receive either ribociclib or palbociclib, along with standard endocrine therapy. Ribociclib is taken as a film-coated tablet, while palbociclib is available in hard capsule form. The study will also include a group receiving a placebo. The trial will monitor the participants over a period to assess how well the treatments work in controlling the cancer and improving the quality of life for patients.
The study will involve regular visits to the clinic for treatment and monitoring. Participants will undergo various tests to track the progress of their condition and the effects of the treatment. The trial aims to provide valuable information on the safety and effectiveness of these medications in treating this specific type of breast cancer.



Portugal
Spain