A novel hormonal medication may be an effective, less toxic way to treat breast cancer compared to existing treatments, according to new research.
The most common type of breast cancer, called estrogen receptor-positive (ER+) breast cancer, is often treated by blocking estrogen in the body. However, a new oral treatment that works by stimulating the androgen receptor (AR) may present fewer side effects while being an effective way to fight the disease.
The research, published in The Lancet Oncology earlier this month, demonstrates the effectiveness of a drug called enobosarm in slowing the growth of ER+ breast cancer. Researchers at the University of Adelaide have been developing the treatment for more than 30 years.
“The effectiveness of enobosarm lies in its ability to activate the AR and trigger a natural defence mechanism in breast tissue, thereby slowing the growth of ER+ breast cancer, which relies on the hormone estrogen to grow and spread," said senior co-author Wayne Tilley, the director of the Dame Roma Mitchell Cancer Research Laboratories at the University of Adelaide, in a news release.
The team of researchers tested the treatment on 136 postmenopausal women with advanced or metastatic ER-positive, HER2-negative breast cancer, finding that it resulted in significant anti-tumor activity and was well tolerated by patients, presenting fewer side effects than existing treatments.
Roughly 80% of all breast cancer cases are ER+ breast cancer, and existing standard-of-care hormonal treatments typically involve suppressing estrogen activity in the body or inhibiting the ER. This may be effective at the start, but it can cause severe side effects, and resistance to the treatment often eventually occurs — ultimately resulting in disease progression.
Enobosarm, however, was found to shrink breast cancer tumors without having negative impacts on patients’ quality of life or resulting in masculinizing symptoms.
This development is the first advancement in hormonal treatment for ER+ breast cancer in decades.
"The data strongly encourages more clinical trials for AR-stimulating drugs in treating AR-positive and ER-positive breast cancer,” said co-author Dr. Stephen Birrell, a clinical affiliate of the University of Adelaide, in the news release. “The fact that this drug is well-tolerated also opens possibilities for its use in breast cancer prevention.”
- The University of Adelaide. Strongest contender in decades in fight against breast cancer.