NCT06377852From ClinicalTrials.govRecruiting

The CDK4/6 Inhibitor Dosing Knowledge (CDK) Study

Comparing Oral Drug Dosing Strategies in Older Patients With Metastatic Breast Cancer to Maximize Tolerance and Reduce Discontinuation: The CDK4/6 Inhibitor Dosing Knowledge (CDK) Study

Metastatic Breast Cancer

At a glance

Phase: Phase 3
Study type: Interventional
Sponsor: American Society of Clinical Oncology
Enrolment target: 500
Started: 29 October 2024
Main results due: 31 August 2028
Study sites: 83
Registry updated: 25 September 2026

Can you take part?

Aged 60 years and over.
Open to any sex.
You need the condition being studied — healthy volunteers are not accepted.

These are the headline rules only. Every study has a longer list, and whether you are eligible is decided by the research team at the site — never by this page.

Read the full eligibility criteria

Inclusion Criteria:

1. Hormone receptor positive (HR+) HER2 negative metastatic breast cancer. Cut-off values for positive/negative staining should be as per standard practice in accordance with ASCO/CAP (American Society of Clinical Oncology/College of American Pathologists) guidelines. Verification of histology is preferred at the time of recurrence and where not possible or necessary in the judgment of the treating physician, the study will accept histology from the initial diagnosis.
2. Candidate for planned endocrine therapy in combination with 1st use of palbociclib or ribociclib, in the metastatic setting. The planned endocrine partner can be an aromatase inhibitor (letrozole, anastrozole, exemestane) or fulvestrant, selected through patient/provider choice.
3. Aged 60 years or older
4. Adequate bone marrow and organ function. Laboratory values must be within normal institutional limits, or within ranges as indicated below, or demonstrate minor abnormalities that are deemed clinically non-significant by the investigator.

* 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.

Exclusion Criteria:

1. Previous treatment with a CDK4/6 inhibitor for metastatic breast cancer, or previous treatment within the past 12 months with a CDK4/6 inhibitor in the neo/adjuvant breast cancer setting.
2. Received greater than 60 days (in the metastatic setting) of the specific endocrine therapy agent planned as partner to the CDK4/6 inhibitor in the study at the time of randomization.
3. Known history of intolerance or allergy to the planned agents used in this trial.
4. Uncontrolled intercurrent illness that, as evaluated by the treating clinician, would hinder compliance with study requirements.
5. Concurrent therapy with other investigational agents or anticancer therapy beyond aromatase inhibitors or fulvestrant. Note: radiation is allowed at any time.
6. Rapidly progressive brain metastases. Note: only applies to patients with known brain metastases. Brain imaging not required for enrollment.
7. Active or chronic Hepatitis B or C are eligible provided they meet liver function laboratory criteria and are not on medication with a known interaction with the study agents.
8. Current use of drugs that have known potential to prolong the QT interval (e.g., antiarrhythmic drugs), for patients on ribociclib. Note: If concomitant use cannot be avoided, monitor ECG when initiating, during concomitant use, and as clinically indicated. Refer to crediblemeds.org as a resource.
9. Prior or concurrent malignancies that are undergoing active treatment.

What this study is about

In the sponsor’s own words, from the registry.

The purpose of this study is to generate evidence on an alternative dosing strategy for CDK4/6 inhibitors to help more patients with Metastatic Breast Cancer (MBC) (age ≥ 60 years) tolerate side effects and stay on treatment longer, to derive the most clinical benefit from these drugs.

The primary objective of the CDK Study is to compare time to treatment discontinuation (TTD) on the approved dosing for palbociclib (125 mg orally daily on days 1-21 of 28-day cycle) or ribociclib (600 mg orally daily on days 1-21 of 28-day cycle) vs. TTD using titrated dosing approach with the same schedule but starting at a lower dose of palbociclib (100 mg or 75 mg) or ribociclib (400 mg or 200 mg) and escalating the dose if well-tolerated in combination with provider/patient choice endocrine therapy (aromatase inhibitor (AI) or fulvestrant) in patients age 60 or older with HR+/HER2- MBC. The secondary and exploratory objectives will generate evidence needed to personalize treatment decisions by comparing patient-centric secondary outcomes and evaluating baseline factors.

Together with their treating physician, participants will choose the CDK4/6 inhibitor (palbociclib or ribociclib) and which endocrine therapy (aromatase inhibitor or fulvestrant) of their choice but will be randomized to either Arm 1 (indicated dosing) or Arm 2 (titrated dosing).

Note: Telehealth visits are allowed at any time per institutional guidelines. In addition, the study allows for remote consenting per institutional guidelines.

Study sites(83)

Ironwood Cancer & Research Centers
Chandler, Arizona, United States
Recruiting
Ironwood Cancer & Research Centers
Gilbert, Arizona, United States
Recruiting
Ironwood Cancer & Research Centers
Glendale, Arizona, United States
Recruiting
Ironwood Cancer & Research Centers
Goodyear, Arizona, United States
Recruiting
Ironwood Cancer & Research Centers
Mesa, Arizona, United States
Recruiting
Ironwood Cancer & Research Centers
Mesa, Arizona, United States
Recruiting
Ironwood Cancer & Research Centers
Phoenix, Arizona, United States
Recruiting
Ironwood Cancer & Research Centers
Scottsdale, Arizona, United States
Recruiting
Providence Medical Foundation
Eureka, California, United States
Recruiting
Providence Medical Foundation
Santa Rosa, California, United States
Recruiting
University of Colorado Anschutz Medical Campus
Aurora, Colorado, United States
Recruiting
UCHealth Cherry Creek Medical Center
Denver, Colorado, United States
Recruiting
UCHealth Highlands Ranch Hospital
Highlands Ranch, Colorado, United States
Recruiting
Smilow Cancer Hospital Care Center - Derby
Derby, Connecticut, United States
Recruiting
Smilow Cancer Hospital Care Center - Fairfield
Fairfield, Connecticut, United States
Recruiting
Smilow Cancer Hospital at Glastonbury
Glastonbury, Connecticut, United States
Recruiting
Smilow Cancer Hospital Care Center - Greenwich
Greenwich, Connecticut, United States
Recruiting
Smilow Cancer Hospital Care Center - Guilford
Guilford, Connecticut, United States
Recruiting
Smilow Cancer Hospital at Saint Francis
Hartford, Connecticut, United States
Recruiting
Smilow Cancer Hospital - Yale New Haven Health
New Haven, Connecticut, United States
Recruiting
Yale University/Yale Cancer Center/Yale School of Medicine
New Haven, Connecticut, United States
Recruiting
Smilow Cancer Hospital Care Center - North Haven
North Haven, Connecticut, United States
Recruiting
Smilow Cancer Hospital Care Center - Torrington
Torrington, Connecticut, United States
Recruiting
Smilow Cancer Hospital Care Center - Trumbull
Trumbull, Connecticut, United States
Recruiting
Smilow Cancer Hospital Care Center - Waterbury
Waterbury, Connecticut, United States
Recruiting
Smilow Cancer Hospital - Waterford
Waterford, Connecticut, United States
Recruiting
Miami Cancer Institute
Miami, Florida, United States
Recruiting
Miami Cancer Institute
Plantation, Florida, United States
Recruiting
Emory University Winship Cancer Institute
Atlanta, Georgia, United States
Recruiting
Liberty County Cancer Care
Hinesville, Georgia, United States
Recruiting
Pembroke Medical Oncology & St Joseph's/Candler Oncology Infusion Suite
Pembroke, Georgia, United States
Recruiting
Lewis Cancer and Research Pavilion
Savannah, Georgia, United States
Recruiting
Candler Medical Oncology Practice and Infusion
Statesboro, Georgia, United States
Recruiting
The University of Kansas Cancer Center
Westwood, Kansas, United States
Recruiting
The Jackson Laboratory (JAX) - Harold Alfond Center for Cancer Care
Augusta, Maine, United States
Recruiting
The Jackson Laboratory (JAX) - Northern Light Cancer Care
Brewer, Maine, United States
Recruiting
Dana-Farber Cancer Institute
Boston, Massachusetts, United States
Recruiting
Dana-Farber Brigham Cancer Center Foxborough
Foxborough, Massachusetts, United States
Recruiting
Dana-Farber Cancer Institute Merrimack Valley
Methuen, Massachusetts, United States
Recruiting
Dana-Farber Brigham Cancer Center at Milford Regional Medical Center
Milford, Massachusetts, United States
Recruiting
Dana-Farber Brigham Cancer Center at South Shore Health
Weymouth, Massachusetts, United States
Recruiting
Dana-Farber/New Hampshire Oncology-Hematology
Londonderry, New Hampshire, United States
Recruiting
Englewood Hospital
Englewood, New Jersey, United States
Recruiting
Capital Health Medical Center - Hopewell
Pennington, New Jersey, United States
Recruiting
Penn Medicine - Princeton Health
Plainsboro, New Jersey, United States
Recruiting
Lovelace Medical Center - Saint Joseph Square
Albuquerque, New Mexico, United States
Recruiting
Lovelace Women's Hospital
Albuquerque, New Mexico, United States
Recruiting
Presbyterian Kaseman Hospital
Albuquerque, New Mexico, United States
Recruiting
The University of New Mexico Comprehensive Cancer Center
Albuquerque, New Mexico, United States
Recruiting
Memorial Medical Center
Las Cruces, New Mexico, United States
Recruiting
Presbyterian Rust Medical Center/Jorgensen Cancer Center
Rio Rancho, New Mexico, United States
Recruiting
Levine Cancer Institute
Albemarle, North Carolina, United States
Recruiting
Levine Cancer Institute
Charlotte, North Carolina, United States
Recruiting
Levine Cancer Institute
Charlotte, North Carolina, United States
Recruiting
Levine Cancer Institute
Charlotte, North Carolina, United States
Recruiting
Levine Cancer Institute
Charlotte, North Carolina, United States
Recruiting
Levine Cancer Institute
Charlotte, North Carolina, United States
Recruiting
Levine Cancer Institute
Concord, North Carolina, United States
Recruiting
Levine Cancer Institute
Forest City, North Carolina, United States
Recruiting
Levine Cancer Institute
Gastonia, North Carolina, United States
Recruiting

Showing 60 of 83 sites — filter to narrow it down. 83 of the 83 sites on this study are recruiting right now — a site can stop enrolling while the study as a whole is still open.

Source: ClinicalTrials.gov record NCT06377852. Trialion does not run this study, is not paid to refer anyone to it, and cannot enrol you. Eligibility is always decided by the research team at the site.

Not the right study?

Answer three questions and see the studies recruiting near you, in plain language.

Find a study for me