Summary
This is a phase I, First-in-Human (FIH), open-label study to evaluate the safety,
tolerability, pharmacokinetic (PK) profile, and preliminary efficacy of RGT-419B
administered orally as monotherapy OR in combination with Hormonal Therapy in subjects
with HR+, HER2- locally advanced and unresectable (Stage III) or metastatic (Stage IV)
breast cancer whose disease has progressed during prior therapy with an approved CDK4/6i
plus hormonal therapy.