Breast cancer metastasis (also known as “stage IV”) occurs when cancer cells leave the breast and travel to other parts of the body in the bloodstream or via the lymphatic system. The most common sites of spread are the liver, brain, bones, and lungs. About 30% of women diagnosed with early-stage breast cancer will ultimately develop metastatic disease. About 55% of women with HER2-positive breast cancer will progress to stage 4. Metastasis greatly impacts long-term survival; for breast cancer patients whose cancer has metastasized to the brain, the life expectancy is only about six months.
Brain metastases are difficult to reach and often are not susceptible to the same treatments as breast cancers in other parts of the body because they are blocked by the blood-brain barrier. However, a new study from Northwestern Medicine is reports some positive findings on a new treatment option.
A new combination therapy including a class of drug known as a BET inhibitor, greatly decreased the size of brain mets and increased survival in mice. About 75% of the mice who underwent this new treatment were cancer-free following the treatment. The BET inhibitor appears to sensitize breast cancer brain metastases to vinorelbine, a drug already approved by the FDA, demonstrating a potentially very promising therapeutic combination.
“The new combination therapy we identified can cross the blood-brain barrier,” said lead study author Dr. Maciej Lesniak, Northwestern Medicine chair of neurological surgery and professor of neurosurgery at Northwestern University Feinberg School of Medicine. “The therapy also targets brain metastases and significantly improves survival.”
The drug I-BET-762, used in combination with vinorelbine in the study, is only approved for trials by the FDA at this time.