Title: A phase II trial of onapristone in combination with fulvestrant for patients with ER-positive and HER2-negative metastatic breast cancer after progression on endocrine therapy and CDK 4/6 inhibitors

Principal Investigator: Kari B. Wisinki, MD, of the University of Wisconsin in Madison

Description: Researchers are conducting a phase 2 trial to test onapristone in combination with fulvestrant in patients with previously treated, estrogen receptor (ER)-positive, HER2-negative, locally advanced or metastatic breast cancer.

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Patients will receive onapristone at 50 mg twice daily during each 28-day cycle. They will also receive fulvestrant at 500 mg via intramuscular injection on days 1 and 15 during cycle 1, on day 1 of cycle 2, and once every 28 days thereafter. 

The primary outcome is objective response rate. Secondary outcomes include progression-free survival, disease control rate, time to response, duration of response, and the incidence of adverse events.

To be eligible for this study, patients must be 18 years of age or older, and they must have ER-positive, HER2-negative advanced breast cancer. Patients must have received prior endocrine therapy in the adjuvant or metastatic setting, and they must have received prior treatment with CDK4/6 inhibitors in the metastatic setting. Other therapies are allowed as well. For a complete list of eligibility criteria, please see the reference.

Status: Recruiting

This study is sponsored by the University of Wisconsin, Madison, in collaboration with Context Therapeutics Inc.


ClinicalTrials.gov. Onapristone and fulvestrant for ER+ HER2- metastatic breast cancer after endocrine therapy and CDK4/6 inhibitors (The SMILE Study). NCT04738292. Accessed February 21, 2023.