First RX for HER2-Low Breast Cancer Gets Green Light

The US Food and Drug Administration (FDA) approves a new breast cancer treatment.

This approval is for Enhertu (fam-trastuzumab-deruxtecan-nxki). 

It is approved to treat those with HER2-low breast cancer

• that is unable to be removed and
• has spread to other parts of the body

Enhertu is the first treatment approved to target the HER2-low breast cancer subtype. 

HER2-low breast cancer is a new subtype of breast cancer. In other words, a subset of HER2-negative breast cancer.

According to the FDA, HER2-low breast cancer is classified as having some HER2 proteins on the cell surface, but does have enough to be classified as HER2-positive.

Those with HER2-low patients received endocrine therapy or chemotherapy — until now. 

Enhertu offers a new option that is given into the vein. 

The approval is a result of the results from a clinical trial that included over 550 patients. 

The most common adverse reactions seen in the clinical trial were

• constipation/diarrhea
• decreased appetite
• fatigue
• loss of hair
• muscle pain and
• nausea/vomiting

There is a boxed warning with this medication which is for the risk of interstitial lung disease and harm to an unborn baby.

This approval is granted to Daiichi Sankyo.