Title: First-in-human, escalating oral dose study of RGT-419B given alone and with endocrine therapy in subjects with hormone receptor positive, human epidermal growth factor receptor 2 negative advanced/metastatic breast cancer

Study Director: Marjorie Zettler, PhD, of Regor Pharmaceuticals, Inc.

Description: Researchers are conducting a phase 1 trial to evaluate RGT-419B, a CDK2/4/6 inhibitor, in patients with hormone receptor (HR)-positive, HER2-negative stage III/IV breast cancer. 

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The trial is enrolling patients whose disease progressed during prior treatment with a CDK4/6 inhibitor and hormonal therapy. 

In this 2-arm study, patients will be assigned to receive RGT-419B alone or in combination with hormonal therapy (selective estrogen receptor degrader, selective estrogen receptor modulator, or aromatase inhibitor).

The primary outcome measure is the number of patients with dose-limiting toxicities. Secondary outcome measures include treatment-emergent adverse events, pharmacokinetics, and tumor response.

To participate in this study, patients must be 18 years of age or older and have HR-positive, HER2-negative, stage III or IV breast cancer. For a complete list of eligibility criteria, please see the reference.

Status: Recruiting

This study is sponsored by Regor Pharmaceuticals, Inc.


ClinicalTrials.gov. First-in-human study of RGT-419B alone and with endocrine therapy in subjects with HR-positive, HER2-negative advanced/metastatic breast cancer. NCT05304962. Accessed June 22, 2022.