NEW YORK – Veru, a Miami-based cancer drugmaker, on Wednesday said it has begun enrolling previously treated hormone receptor (HR)-positive, HER2-negative metastatic breast cancer patients in a Phase III trial of its anti-androgen receptor therapy enobosarm.
The registration-directed trial, dubbed ARTEST, is specifically exploring the activity of enobosarm in advanced breast cancer patients with androgen receptor (AR)-positive and estrogen receptor (ER)-positive tumors that have progressed after treatment with estrogen blocking agents and CDK4/6 inhibitors.
To determine trial eligibility, Veru is using a diagnostic test to assess patients' androgen receptor status, which will be validated as a companion diagnostic for enobosarm. Patients will need to have androgen receptor nuclei staining of at least 40 percent in tissue samples to be eligible for the trial. This cutoff, which was established in another Phase II enobosarm trial, will qualify 57 percent of women with AR-positive, ER-positive, HER2-negative metastatic breast cancer for treatment, the firm estimated.
"Targeting patients expressing the androgen receptor allows us to focus a new endocrine approach on patients that have become resistant to existing therapies," Adam Brufsky, co-director of the University of Pittsburgh Medical Center's Comprehensive Breast Cancer Center and principal investigator on the ARTEST trial, said in a statement.
In the Phase III trial, Veru will randomize 210 patients to either single-agent enobosarm or the standard-of-care regimen containing the estrogen modulator exemestane (Pfizer's Aromasin) with or without chemotherapy. As a primary endpoint, the firm will determine if enobosarm-treated patients have better radiographic progression-free survival versus those on standard treatment. Secondary endpoints include overall response rate, overall survival, duration of response, and quality of life.
In addition to the ARTEST trial, Veru is evaluating enobosarm in combination with abemaciclib (Eli Lilly's Verzenio) as a second-line treatment for HR-positive, HER2-negative metastatic breast cancer patients after palbociclib (Pfizer's Ibrance) and either a nonsteroidal aromatase inhibitor or fulvestrant. The firm will begin enrolling patients to this Phase III trial, dubbed ENABLAR-2, during the fourth quarter of this year.