The oral cyclin-dependent kinase (CDK) 4/6 inhibitor abemaciclib (Verzenio – Lilly) has been approved by the FDA for use in combination with endocrine therapy (tamoxifen or an aromatase inhibitor) for adjuvant treatment of patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, node-positive, early breast cancer at high risk of recurrence.1It was previously approved for the same indication, but patients were also required to have a Ki-67 score ≥20%. About 70% of all breast cancers are HR-positive and HER2-negative. Ki-67 is a prognostic biomarker for tumor proliferation; a score ≥20% is associated with early recurrence and poor prognosis.

The oral cyclin-dependent kinase (CDK) 4/6 inhibitor abemaciclib (Verzenio – Lilly), which was approved by the FDA in 2017 for treatment of hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer, has now been approved for use in combination with endocrine therapy (tamoxifen or an aromatase inhibitor) for adjuvant treatment of patients with HR-positive, HER2-negative, node-positive, early breast cancer at high risk of recurrence and a Ki-67 score ≥20%.

The FDA has approved abemaciclib (Verzenio – Lilly), an oral cyclin-dependent kinase (CDK) 4/6 inhibitor, for treatment of hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer. Abemaciclib is the third CDK 4/6 inhibitor to be approved in the US for this indication.

The oral cyclin-dependent kinase (CDK) 4/6 inhibitor ribociclib (Kisqali – Novartis) has been approved by the FDA for use in combination with an aromatase inhibitor for first-line endocrine-based therapy in postmenopausal women with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer. Ribociclib is also available copackaged with the aromatase inhibitor letrozole (Femara, and generics) as Kisqali Femara Co-Pack. Ribociclib is the second CDK 4/6 inhibitor to be approved in the US for this indication; palbociclib (Ibrance) was the first. Abemaciclib (Verzenio), a third CDK 4/6 inhibitor, was recently approved and will be reviewed in a future issue.