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Recruiting Phase 3 NCT06377852

NCT06377852 The CDK4/6 Inhibitor Dosing Knowledge (CDK) Study

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Clinical Trial Summary
NCT ID NCT06377852
Status Recruiting
Phase Phase 3
Sponsor American Society of Clinical Oncology
Condition Metastatic Breast Cancer
Study Type INTERVENTIONAL
Enrollment 500 participants
Start Date 2024-10-29
Primary Completion 2028-08-31

Eligibility & Interventions

Sex All sexes
Min Age 65 Years
Max Age N/A
Study Type INTERVENTIONAL
Interventions
Palbociclib 125mgRibociclib 600mgRibociclib

Eligibility Fast-Check

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What to Expect as a Participant

You will actively receive the study intervention — which may be a drug, biologic, device, or procedure.

Phase 3 trials are large pivotal studies comparing the treatment to current standard of care or placebo. Your participation directly contributes to the evidence needed for regulatory approval.

This trial targets 500 participants in total. It began in 2024-10-29 with a primary completion date of 2028-08-31.

⚠ This information is for research awareness only. Always consult your physician before joining any clinical trial. Participation is voluntary and you may withdraw at any time.

Brief Summary

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.

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 65 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 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. 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. 6. Rapidly progressive brain metastases. 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.

Contact & Investigator

Central Contact

Jackie Perez, MPH

✉ CDKstudy@asco.org

📞 571-483-1300

Principal Investigator

Julie Gralow, MD

PRINCIPAL INVESTIGATOR

American Society of Clinical Oncology

Frequently Asked Questions

Who can join the NCT06377852 clinical trial?

This trial is open to participants of all sexes, aged 65 Years or older, studying Metastatic Breast Cancer. Full inclusion and exclusion criteria are listed in the Eligibility Criteria section. Always confirm your eligibility with the research team before applying.

What phase is the NCT06377852 trial and what does that mean for participants?

Phase 3 trials are large-scale studies comparing the new treatment to existing standards of care or a placebo. They provide the evidence needed for regulatory approval. This trial targets 500 participants.

Is NCT06377852 currently recruiting?

Yes, NCT06377852 is actively recruiting participants. Contact the research team at CDKstudy@asco.org for enrollment information.

Where is the NCT06377852 trial being conducted?

This trial is being conducted at Chandler, United States, Gilbert, United States, Glendale, United States, Goodyear, United States and 11 additional locations.

Who is sponsoring the NCT06377852 clinical trial?

NCT06377852 is sponsored by American Society of Clinical Oncology. The principal investigator is Julie Gralow, MD at American Society of Clinical Oncology. The trial plans to enroll 500 participants.

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ClinicalMetric — Independent clinical trial intelligence platform. Not affiliated with NIH, ClinicalTrials.gov, the U.S. FDA, or any pharmaceutical company, hospital, or clinical research organization. Trial data is sourced from ClinicalTrials.gov for informational purposes only and does not constitute medical advice. Do not make any treatment, enrollment, or health decisions based solely on information found here — always consult a qualified healthcare professional. Full Disclaimer  ·  Last Reviewed: April 2026  ·  Data Methodology