ECI830 + fulvestrant

**ECI830 + fulvestrant** is an investigational combination therapy being studied primarily for the treatment of advanced hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer. ECI830 is a small molecule inhibitor targeting cyclin-dependent kinase 2 (CDK2), while fulvestrant is a selective estrogen receptor degrader (SERD) that antagonizes and promotes degradation of the estrogen receptor. The combination is designed to inhibit cell cycle progression in tumors driven by both aberrant CDK2/cyclin E signaling and estrogen receptor activity. The main study context involves use in combination with ribociclib (a CDK4/6 inhibitor) and fulvestrant, though information specific to just ECI830 + fulvestrant as a pair is primarily derived from clinical trials evaluating multi-agent regimens in breast cancer patients resistant to prior endocrine therapy[1][3][4][5][7][9][10].