Phase 1 Study of Oral RGT-419B Alone or With Hormonal Therapy in Adults With Advanced or Metastatic HR-Positive, HER2-Negative Breast Cancer

What this Trial Is About

Researchers are evaluating the safety, tolerability, pharmacokinetics, and preliminary effectiveness of RGT-419B in people with hormone receptor-positive, HER2-negative advanced or metastatic breast cancer. This phase I, open-label study includes participants whose disease has progressed after prior treatment with a CDK46 inhibitor plus hormonal therapy. The study is focused on patients with Stage III locally advanced unresectable or Stage IV metastatic breast cancer. Participants receive RGT-419B either alone as monotherapy or combined with hormonal therapy, including selective estrogen receptor degraders, modulators, or aromatase inhibitors. The study uses escalating oral doses in a sequential design to assess safety and drug behavior. This first-in-human trial includes two experimental arms for comparison between monotherapy and combination therapy. During the study, participants are monitored for dose-limiting toxicities over a 4-week cycle and followed for an average of one year to assess overall safety, drug levels, tumor response, and heart rhythm changes. Researchers collect blood and urine samples for pharmacokinetic analysis and evaluate tumor size using RECIST criteria. The study involves regular assessments to monitor treatment effects and safety throughout participation, which may last up to several years.

FIH Study of RGT-419B Alone and With Endocrine Therapy in HR-Positive, HER2-Negative Advanced/Metastatic Breast Cancer