The CDK4/6 Inhibitor Dosing Knowledge (CDK) Study

Recruiting now · Phase 3

Conditions studied: Metastatic Breast Cancer

In brief

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 ≥ 65 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 65 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.

Key facts

Study ID

NCT06377852

Run by

American Society of Clinical Oncology

People needed

500

Starts

2024-10-29

Expected to finish

2028-09-01

Last updated by the study team

2026-06-29

Who can join

Age: 65 and older. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• 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.
• 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.
• Aged 65 years or older
• 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.
• Baseline QTc ≤ 480 ms (only for ribociclib patients)
• Ability to understand and the willingness to provide informed consent. Note: Remote consent is allowed per institutional guidelines.

You may not qualify if…

• 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.
• Received greater than 30 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.
• Known history of intolerance or allergy to the planned agents used in this trial.
• Uncontrolled intercurrent illness that, as evaluated by the treating clinician, would hinder compliance with study requirements.
• Concurrent therapy with other investigational agents.
• Rapidly progressive brain metastases.
• 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.
• 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.
• Prior or concurrent malignancies that are undergoing active treatment.

Where it is running

• Ironwood Cancer & Research Centers — Gilbert, Arizona, United States (enrolling)
• Ironwood Cancer & Research Centers — Glendale, Arizona, United States (enrolling)
• Ironwood Cancer & Research Centers — Goodyear, Arizona, United States (enrolling)
• Ironwood Cancer & Research Centers — Mesa, Arizona, United States (enrolling)
• Ironwood Cancer & Research Centers — Mesa, Arizona, United States (enrolling)
• Ironwood Cancer & Research Centers — Phoenix, Arizona, United States (enrolling)
• Ironwood Cancer & Research Centers — Scottsdale, Arizona, United States (enrolling)
• University of Colorado Anschutz Medical Campus — Aurora, Colorado, United States (enrolling)
• UCHealth Cherry Creek Medical Center — Denver, Colorado, United States (enrolling)
• UCHealth Highlands Ranch Hospital — Highlands Ranch, Colorado, United States (enrolling)
• Smilow Cancer Hospital Care Center - Derby — Derby, Connecticut, United States (enrolling)
• Smilow Cancer Hospital Care Center - Fairfield — Fairfield, Connecticut, United States (enrolling)
• Smilow Cancer Hospital at Glastonbury — Glastonbury, Connecticut, United States (enrolling)
• Smilow Cancer Hospital Care Center - Greenwich — Greenwich, Connecticut, United States (enrolling)
• Smilow Cancer Hospital Care Center - Guilford — Guilford, Connecticut, United States (enrolling)
• Smilow Cancer Hospital at Saint Francis — Hartford, Connecticut, United States (enrolling)
• Smilow Cancer Hospital - Yale New Haven Health — New Haven, Connecticut, United States (enrolling)
• Yale University/Yale Cancer Center/Yale School of Medicine — New Haven, Connecticut, United States (enrolling)
• Smilow Cancer Hospital Care Center - North Haven — North Haven, Connecticut, United States (enrolling)
• Smilow Cancer Hospital Care Center - Torrington — Torrington, Connecticut, United States (enrolling)
• Smilow Cancer Hospital Care Center - Trumbull — Trumbull, Connecticut, United States (enrolling)
• Smilow Cancer Hospital Care Center - Waterbury — Waterbury, Connecticut, United States (enrolling)
• Smilow Cancer Hospital - Waterford — Waterford, Connecticut, United States (enrolling)
• Miami Cancer Institute — Miami, Florida, United States (enrolling)
• Ironwood Cancer & Research Centers — Chandler, Arizona, United States (enrolling)

Full record on ClinicalTrials.gov

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