Ribociclib is a kinase inhibitor indicated in combination with: • an aromatase inhibitor for the treatment of pre/perimenopausal or postmenopausal women with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)- negative advanced or metastatic breast cancer, as initial endocrine-based therapy.

The most common side effects include infections, low levels of white blood cells, headache, cough, nausea (feeling sick), vomiting, diarrhoea, constipation, tiredness, hair loss and rash. The most common severe side effects include infections, low levels of red and white blood cells, vomiting, abnormal blood tests for liver function and low levels of phosphate in the blood (hypophosphataemia).

In September 2024, the US Food and Drug Administration (FDA) expanded the indication for ribociclib, in combination with an aromatase inhibitor, for the adjuvant treatment of adults with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative stage II and III early breast cancer at high risk of recurrence.