Study of Pre-Operative Radiation Combined with Abemaciclib and Letrozole for Early Stage Hormone Receptor PositiveHER2 Negative Breast Cancer

What this Trial Is About

Researchers are investigating the safety and feasibility of combining pre-operative radiation therapy with Cyclin-Dependent Kinase 4 CDK46 inhibitors in women aged 60 and older diagnosed with hormone receptor positiveHER2 negative HRHER2- breast cancer. This phase 1b study focuses on understanding how well this combined treatment is tolerated and its potential benefits for this specific breast cancer subtype. Participants will receive abemaciclib at varying doses twice daily along with letrozole daily for three 28-day cycles before starting targeted radiation therapy. The study includes several parts initial combined drug treatment, followed by radiation therapy while continuing the drugs, additional cycles of the medications, and finally surgery. Biopsies and dose adjustments are part of the treatment plan to monitor safety and dosing. Throughout the study, participants will undergo detailed clinical assessments, imaging, laboratory tests, and biopsies to track treatment responses and possible side effects. Researchers will monitor safety by recording adverse events regularly over five years and evaluate outcomes such as residual cancer burden, post-operative complications, breast-conserving surgery rates, and disease-free survival. The total study participation includes long-term follow-up to assess both safety and treatment effects.

RADIANT: Pre-op Radiation With Abemaciclib and Letrozole