The FDA has approved elacestrant (Orserdu – Stemline), an oral estrogen receptor antagonist, for treatment of estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, estrogen receptor 1 (ESR1)-mutated advanced or metastatic breast cancer in postmenopausal women or men who had disease progression following endocrine therapy. Elacestrant is the first oral selective estrogen receptor degrader (SERD) to be approved for treatment of breast cancer; the injectable SERD fulvestrant (Faslodex, and generics) was approved more than 20 years ago.

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.

Palbociclib (Ibrance – Pfizer), an oral cyclin-dependent kinase inhibitor, has been approved by the FDA for use in combination with the aromatase inhibitor letrozole (Femara, and generics) for first-line treatment of postmenopausal women with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer. It is the first cyclin-dependent kinase inhibitor to become available in the US.