The FDA has approved imlunestrant (Inluriyo – Lilly), 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 adults who had disease progression following at least one prior line of endocrine therapy. Imlunestrant is the second oral selective estrogen receptor degrader (SERD) to be approved in the US for treatment of breast cancer; elacestrant (Orserdu) was approved in 2023.

The oral cyclin-dependent kinase (CDK) 4/6 inhibitor ribociclib (Kisqali – Novartis), which was approved by the FDA in 2017 for use with an aromatase inhibitor or fulvestrant 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 with an aromatase inhibitor for adjuvant treatment of HR-positive, HER2-negative stage II or III early breast cancer at high risk of recurrence. Kisqali can be used in patients with node-positive or node-negative disease. The CDK 4/6 inhibitor abemaciclib (Verzenio) is also approved for use in early breast cancer, but only in patients with node-positive disease.

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.