Anti-Androgen Drugs May Benefit Triple-Negative Breast Cancer Patients

Study reveals optimistic findings for patients without other options for targeted cancer therapy.

Patients with triple-negative breast cancer who have been left without any FDA-approved targeted therapies may soon have some good news in their fight against the disease.

In a study recently published in the journal Molecular Cancer Therapeutics, researchers found that only about 1% of triple-negative breast cancer cells in a tumor need to be androgen-receptor-positive in order to benefit from anti-androgen therapies. Clinical trials currently underway have shown promising preliminary results from anti-androgen-receptor therapies against triple-negative breast cancers that express higher percentages of androgen-receptor-positive cells.

"What we're showing is that the threshold for benefit from anti-androgen-receptor therapies in triple-negative breast cancer may be far lower than we previously thought,” study first author Valerie Barton said in a press release. “This is an extremely optimistic finding for many people who have been without options for targeted cancer therapy.”

Short of a known hormone or genetic driver, triple-negative breast cancer treatment has lacked a specific target for targeted therapies. As a result, the triple-negative subtype carries the lowest 5-year survival rate of any breast cancer, the study noted.

Studies like the current trial conducted at the University of Colorado Cancer Center seek to prove androgen receptors are an additional driver and target for cancer treatment.

"We're getting closer to being able to call some triple-negative breast cancers, androgen-receptor-positive breast cancers,” Barton noted. “And we may have to start referring to the remaining triple-negative breast cancers that are completely without androgen receptors as quadruple-negative breast cancers.”

The current study used Enzalutamide, which was previously approved by the FDA as an anti-androgen against prostate cancer, to treat triple-negative breast cancer cells. The drug was previously found to be active against luminal triple-negative breast cancer cells that typically have abundant androgen receptors.

The researchers evaluated Enzalutamide in the treatment of non-luminal triple-negative breast cancer cell lines with significantly less androgen receptors.

"Even in these cells and in mouse models of tumors with low percentage of androgen receptor positive breast cancer cells, we observed that Enzalutamide was significantly effective at reducing proliferation, growth, migration and invasion of cancer cells," Barton said. "Our results suggest that anti-androgen receptor therapy may benefit a larger percentage of triple negative breast cancers than previously thought.”