Denise A. Yardley, MD, hematologist/oncologist, Sarah Cannon Research Institute, discusses a pilot study that assessed safety, pharmacokinetics, and effects on circulating estrogens in women with advanced hormone receptor (HR)-positive breast cancer treated with enzalutamide plus exemestane.
Yardley says enzalutamide, an androgen receptor antagonist, plays an interesting role in breast cancer. There is a lot of interest in the androgen receptor in breast cancer, since it is present in about 75% of all breast cancers.
To explore this further, the pilot study treated patients in 2 cohorts: one where patients have had one prior endocrine therapy for advanced disease while the other group contained chemotherapy and endocrine naïve patients, Yardley says. The patients received 160mg of enzalutamide combined with 50mg of exemestane.
The rationale for this trial was based on previous data demonstrating that androgens via aromatase are converted to estradiol and estrone. By using an aromatase inhibitor alone, it is believed that the amount of androgen is increased, warranting the addition of an androgen receptor antagonist. To date, the combination has been efficacious and well tolerated.
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