CDK4/6 Inhibitor Dosing for Metastatic Breast Cancer

This study, called the CDK Study, is for people aged 65 or older with hormone receptor-positive (HR+) and HER2-negative metastatic breast cancer. It's looking at different ways to give two common medicines, palbociclib and ribociclib, which are CDK4/6 inhibitors. One group will receive the standard dose, while another group will start with a lower dose and slowly increase it if they tolerate it well. The goal is to see if starting with a lower dose helps people stay on treatment longer and experience fewer side effects. The study plans to enroll 500 participants.

Study design
This is a randomized study comparing two dosing approaches for CDK4/6 inhibitors. It aims to enroll 500 participants.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
Participants will be followed for up to 48 months to track how long they stay on treatment.

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NCT06377852

The CDK4/6 Inhibitor Dosing Knowledge (CDK) Study

Recruiting
PHASE3Ages 65+InterventionalTreatment
American Society of Clinical Oncology
~500 participants
Updated 2026-06-29 on ClinicalTrials.gov
What's tested:Palbociclib 125mgRibociclib 600mgRibociclibPalbociclib

At a glance

Recruiting sites
73 of 73 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Time to Treatment Discontinuation (TTD)
Measured over up to 48 months
Metastatic Breast Cancer
73 sites across 17 states
North Carolina14
Connecticut13
Arizona8
New Mexico6
Washington6
Massachusetts5
Pennsylvania4
Colorado3
  • Julie Gralow, MD · PRINCIPAL_INVESTIGATOR · American Society of Clinical Oncology

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Eligibility criteria

Inclusion

Absolute neutrophil count ≥ 1,000/µL
Total bilirubin ≤ 1.5 x institutional upper limit of normal (ULN) (participants with documented Gilbert's disease are allowed total bilirubin up to 5X ULN)
AST (SGOT)/ALT (SGPT) \<3 x institutional ULN, or ≤ 5 x ULN for subjects with documented metastatic disease to the liver. 5. Baseline QTc ≤ 480 ms (only for ribociclib patients) 6. Ability to understand and the willingness to provide informed consent. Note: Remote consent is allowed per institutional guidelines.
  • Time to Treatment Discontinuation (TTD)up to 48 months

    Our primary outcome is time to CDK4/6 inhibitor discontinuation (TTD): the number of days between randomization and the last day the patient takes any dose of the same CDK4/6 inhibitor (regardless of drug holds, dose changes