HR +HER2 Metastatic Breast Cancer & Its New Treatment

What is HR+/HER2- Metastatic Breast Cancer:

Inside a woman`s breast, there are 12 to 20 sections or lobes. Each lobe is made up of different smaller sections named lobules. Fibrous tissue as well as fat mainly occupy the spaces between the lobules and ducts (thin tubes that help connect nipples and lobes). Breast cancer develops when cells in the breast grow and progress in uncontrolled way and form a growth/tumor. The tumors may be either malignant (cancerous) or benign (not cancerous).

HR stands for hormone receptor. HR+ means that tumor cells have receptors for the hormones estrogen or progesterone, which suggests that cancerous cells receive signals from these hormones that promote the growth of HR+ tumors. 

On the other hand, HER2- which stands for human epidermal growth factor receptor 2. HER2- breast cancer have cells that contain tiny to no HER2 protein, so they tend to grow more slowly.

The HR+/HER2- breast cancer is the most common subtype with an age-adjusted rate of 87.4 new cases per 100,000 women, based on 2015 to 2019 cases.

An estimated half of the metastatic breast cancers are both HR+ and HER2- and about 70 % of the time, HR+/HER2- spreads to the bones. 

This subtypes of breast cancer are also commonly found in soft tissues like lymph nodes. The HR+ and HER2- are sometimes found in organs like the liver or lungs. This type of cancer is occasionally seen in the skin.

Newly Approved Treatment of HR+/HER2- Metastatic Breast Cancer:

On 3rd February 2023, the FDA approved Trodelvy (sacituzumab govitecan-hziy) to treat adult patients with unresectable locally advanced or metastatic HR+/HER2- (IHC 0, IHC 1+ or IHC 2+/ISH–) breast cancer who have previously been treated with endocrine-based therapy and at least 2 (two) additional systemic therapies in the metastatic setting.

The proposed dosage of sacituzumab govitecan-hziy for HR+/HER2- metastatic breast cancer is 10 mg/kg administered as an intravenous (IV) infusion once in a week on Days 1st & 8th of three weeks (21 days) treatment cycles until disease progression or unacceptable toxicity.

The most commonly reported side effects in patients treated with Trodelvy injection are diarrhea, nausea, fatigue, alopecia, constipation, increased glucose, decreased white blood cells count, and reduced hemoglobin.

About Trodelvy (sacituzumab govitecan-hziy):