Androgen Receptor Modulator in ER-Positive/AR-Positive Breast Cancer
Posted: Thursday, January 21, 2021
Carlo Palmieri, PhD, of the Clatterbridge Cancer Center NHS Foundation Trust, Liverpool, and colleagues devised a study to determine the efficacy of enobosarm in patients with advanced estrogen receptor (ER)-positive/androgen receptor (AR)-positive breast cancer. Their phase II study results, presented at the 2020 San Antonio Breast Cancer Symposium (SABCS; Abstract PD8-10), showed this treatment had significant clinical activity.
“Given the limited options of hormonal therapy for metastatic ER-positive breast cancer, enobosarm merits further clinical development in a phase III clinical program as an AR-targeted treatment for metastatic ER-positive/AR-positive breast cancer,” the investigators concluded.
This international, open-label study consisted of 136 postmenopausal women with metastatic ER-positive/AR-positive breast cancer who experienced disease progression on hormonal therapy. Participants had a mean of four previous endocrine therapies, and more than 90% had prior chemotherapy. Patients were randomly assigned 1:1 to receive either 18 mg or 9 mg of oral enobosarm daily. Eligible patients had AR positivity, which occurred in 81.2% and 73.6% of patients in the 18-mg and 9-mg cohorts, respectively.
A total of 32% and 29% of patients met the clinical benefit endpoint of 24 weeks in the 9-mg group and 18-mg group, respectively. In the 18-mg cohort, three patients had a complete response, and seven had a partial response; in the 9-mg cohort, 2 had a complete response, and 10 had a partial response. The median progression-free survival for the 18-mg and 9-mg groups were 4.2 months and 5.6 months, respectively. Improvement in anxiety/depression, pain discomfort, and mobility occurred in 50% and 29%, 50% and 31%, and 40% and 50% of patients in the 9-mg and 18-mg groups, respectively. Drug-related severe adverse events were observed in 6 and 10 patients in the 9-mg and 18-mg cohorts, respectively.
Disclosure: For full disclosures of the study authors, visit sabcs.org.
