The FDA has approved margetuximab-cmkb (Margenza – MacroGenics), a HER2/neu receptor antagonist, for use in combination with chemotherapy for treatment of metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer in adults who received ≥2 prior anti-HER2 regimens, at least one of which was for metastatic disease.

Anastrozole (Arimidex - AstraZeneca, Medical Letter 1996; 38:61), an aromatase inhibitor, has received accelerated approval from the FDA for adjuvant treatment of postmenopausal women with early hormone-receptor-positive breast cancer. The drug was approved for treatment of postmenopausal women with metastatic breast cancer in 1996.

A randomized, placebo-controlled, double-blind trial of exemestane (Aromasin, and others) in postmenopausal women considered at increased risk for breast cancer found that the aromatase inhibitor, over a median follow-up of 35 months, significantly decreased the annual incidence of invasive breast cancer from 0.55% to 0.19% (PE Goss et al. N Engl J Med, epub June 4, 2011).

Fam-trastuzumab deruxtecan-nxki (Enhertu – Daiichi Sankyo/AstraZeneca), which received accelerated approval by the FDA in 2019 for treatment of HER2-positive breast cancer based on its rate and duration of response,1 has been granted regular approval for treatment of adults with unresectable or metastatic HER2-positive breast cancer who received a prior anti-HER2-based regimen in the metastatic setting or in the neoadjuvant or adjuvant setting and developed recurrence during or within 6 months of completing treatment.

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.

Ado-trastuzumab emtansine (Kadcyla – Genentech), a human epidermal growth factor receptor 2 (HER2)-targeted antibody and microtubule inhibitor conjugate, has been approved by the FDA for intravenous (IV) treatment of HER2-positive metastatic breast cancer in patients previously treated with trastuzumab (Herceptin) and a taxane. The prefix was added to the new conjugate’s name at the request of the FDA to distinguish it from trastuzumab.

The oral tyrosine kinase inhibitor neratinib (Nerlynx – Puma Biotechnology) has been approved by the FDA for use in combination with capecitabine (Xeloda, and generics) for treatment of advanced or metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer in adults who received ≥2 prior anti-HER2-based regimens for metastatic disease. It was previously approved for use as monotherapy for extended adjuvant treatment of adults with early-stage, HER2-positive breast cancer following adjuvant trastuzumab (Herceptin)-based therapy. HER2 is overexpressed in...

The FDA has approved two new drugs for treatment of previously-treated unresectable or metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer: fam-trastuzumab deruxtecannxki (Enhertu – Daiichi-Sankyo/AstraZeneca), an IV HER2-directed monoclonal antibody linked to the topoisomerase I inhibitor DXd, and tucatinib (Tukysa – Seagen), an oral tyrosine kinase inhibitor.

Inavolisib (Itovebi – Genentech), an oral kinase inhibitor, has been approved by the FDA for use in combination with palbociclib and fulvestrant for treatment of endocrine-resistant, PIK3CA-mutated, hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, locally advanced or metastatic breast cancer. This is the first approval for Itovebi; palbociclib and fulvestrant have been available for years for treatment of HR-positive, HER2-negative breast cancer.

The FDA has approved sacituzumab govitecan-hziy (Trodelvy – Immunomedics), a trophoblast cell-surface antigen-2 (Trop-2)-directed antibody and topoisomerase inhibitor conjugate, for treatment of adults with metastatic triple-negative breast cancer who have received ≥2 prior therapies for metastatic disease. It is the first Trop-2-directed antibody-drug conjugate to become available in the US.