Study Comparing Standard and Lower Starting Doses of CDK46 Inhibitors in Patients 65 and Older With Metastatic Breast Cancer

What this Trial Is About

Researchers are evaluating different dosing strategies of CDK46 inhibitors in patients aged 65 years or older with Hormone Receptor Positive HR and HER2-negative Metastatic Breast Cancer MBC. The study aims to compare the time patients remain on treatment using the standard approved dosing versus a titrated dosing approach that starts at a lower dose and increases if well tolerated. This Phase 3, randomized trial also explores patient-reported outcomes and baseline factors to help personalize treatment for older patients. Participants will choose either palbociclib or ribociclib as their CDK46 inhibitor and select an endocrine therapy partner, either an aromatase inhibitor or fulvestrant. They will be randomized to one of two groups Arm 1 receives the indicated dosing regimen starting at the full approved dose, while Arm 2 starts at a lower dose with potential escalation based on tolerance. Treatment cycles are 28 days long, with the CDK46 inhibitor taken daily for 21 days per cycle. Throughout the study, participants will be monitored for treatment duration, side effects, quality of life, dose adjustments, and healthcare use. Data will be collected up to 48 months, including patient questionnaires and clinical assessments to track tolerability and outcomes. Telehealth visits and remote consenting are permitted to facilitate participation. The study seeks to find dosing strategies that help older patients tolerate treatment longer and improve their clinical benefit.

The CDK4/6 Inhibitor Dosing Knowledge (CDK) Study