Dr. Tolaney on the Importance of Evaluating Enobosarm in ER+ Breast Cancer

Sara M. Tolaney, MD, MPH, chief, Division of Breast Oncology, Susan F. Smith Center for Women's Cancers, associate director, Susan F. Smith Center for Women's Cancers, senior physician, Dana-Farber Cancer Institute, associate professor of Medicine, Harvard Medical School, discusses the importance of evaluating enobosarm in metastatic estrogen receptor (ER)–positive, HER2-negative breast cancer.

Enobosarm is a selective androgen receptor modulator with a unique mechanism of action, Tolaney says. Previous data for enobosarm demonstrated robust clinical activity with the agent in patients with pretreated hormone receptor (HR)–positive breast cancer, Tolaney explains. However, findings from a recent study (NCT02463032) showed that the activity was even greater when looking at patients with high androgen receptor (AR) expression, Tolaney says. Therefore, the AR expression cutoff to evaluate enobosarm was greater than or equal to 40%, which is where objective responses were observed, Tolaney adds.

Moreover, because of these outcomes, there is now the phase 3 ARTEST trial (NCT04869943) is enrolling patients with AR-positive, ER-positive, HER2-negative metastatic breast cancer to compare enobosarm with standard of care endocrine therapy, Tolaney continues. Patients are predominantly requiring a third-line treatment and have to have AR expression of greater than or equal to 40%, Tolaney explains.

Given the previous data observed,enobosarm is a promising oral agent for this select population, Tolaney concludes.