A new drug approved for stage 4 hormone-positive breast cancer: Ribociclib

On 13 March 2017, the FDA approved treatment for advanced and metastatic breast cancer with the active ingredient ribociclib (trade name Kisquali). Ribociclib inhibits cyclin-dependent kinase 4/6, known to affect cancer-cell growth. For postmenopausal women with estrogen receptor-positive (ER-positive), human epidermal growth factor 2-negative (HER2-negative) advanced or metastatic breast cancer, use together with an aromatase inhibitor was considered appropriate as initial treatment, without requiring any previous treatment.

FDA approval was based on an international trial (MONALEESA-2) enrolling postmenopausal women with ER-positive, HER2-negative advanced or metastatic breast cancer who had received no previous treatment for advanced disease. A total of 668 patients were assigned to ribociclib plus letrozole (n = 334) or placebo plus letrozole (n = 334). Ribociclib 600 mg or placebo was taken orally once daily for 21 days followed by a 7-day break, while letrozole 2.5 mg was taken orally once daily for 28 days. Treatment continued until progression or unacceptable side effects.

Estimated median progression-free survival—the time without disease worsening—was not reached in the ribociclib group during the study and was 14.7 months in the placebo arm. In patients with measurable disease, objective response was % 52.7 with ribociclib plus letrozole versus % 37.1 with placebo plus letrozole. Overall survival information is not currently available.

Common side effects include neutropenia, nausea, fatigue, diarrhea, leukopenia, hair loss, vomiting, constipation, headache and low back pain. Ribociclib has also been shown to prolong the ECG QT interval in a concentration-dependent manner.

The recommended starting dose is, for 21 consecutive days, once daily 600 mg (3 tablets of 200mg). Treatment should then be interrupted for 7 days.

New-generation drugs for hormone-positive metastatic breast cancer, palbociclib (Ibrance) and ribociclib (Kisquali), have American FDA approval but are not yet reimbursed in our country. We will announce any inclusion in reimbursement on our website.