Can a lower dose of palbociclib work just as well for advanced breast cancer?

NCT ID NCT02630693

Disease control Sponsor: Canadian Cancer Trials Group Source: ClinicalTrials.gov ↗

First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This completed phase 2 trial enrolled 180 women with ER-positive, HER2-negative advanced or metastatic breast cancer. Researchers compared two different dosing schedules of the targeted drug palbociclib (100 mg daily vs. 125 mg for 3 weeks on, 1 week off) combined with standard hormone therapy. The goal was to see if the lower daily dose could offer similar cancer control with fewer dose interruptions. The study measured progression-free survival and response rates.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance: Palbociclib (a targeted cancer drug) plus endocrine therapy (fulvestrant, tamoxifen, or an aromatase inhibitor)
What this could lead to: If successful, this could identify a better dosing schedule for palbociclib that maintains effectiveness while reducing side effects and dose delays.
What could go wrong: This is a phase 2 trial with only 180 participants, so results may not be definitive. The lower dose might be less effective, and the study does not test a new drug or cure.

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Study facts

What this study's own registry entry says, in plain language.

Phase

Phase 2

Tests whether the treatment actually works, and watches for side effects, in a larger group.

Participants

180 people

The number who actually took part.

Started

Apr 2016

Finished

Nov 2023

Lead sponsor

A research network

The lead sponsor is a research network or cooperative group.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

18 years and older

Sex

Female participants only

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Premenopausal and postmenopausal women 18 years of age or older. * Histologically confirmed adenocarcinoma of the breast, with ER positive and HER2 negative status based on local testing on most recent pathological tumour specimen. * Patients must satisfy the following criteria for prior therapy: * Progressed during treatment or within 12 months of completion of adjuvant endocrine therapy or * Progressed during prior endocrine therapy for advanced/metastatic disease. Note: 'Progressed during endocrine therapy' means that the patient progressed while on or within 1 month after discontinuation of endocrine therapy. * One line of chemotherapy for advanced/metastatic disease (regardless of prior adjuvant chemotherapy use) is allowed in addition to endocrine therapy. * Patients must have evidence of disease to be eligible for the study, but measurable disease is not mandatory. * For those patient with measureable disease who will be included in the response assessment, the following criteria must apply: * X-ray ≥ 20 mm * Spiral CT scan or physical exam ≥ 10 mm (lymph nodes must be ≥ 15 mm in the short axis) * Conventional CT scan, MRI ≥ 20 mm * Measurable lesions must be outside a previous radiotherapy field if they are the sole site of disease, unless disease progression has been documented. Tumor lesions previously irradiated or subjected to other loco regional therapy will only be deemed measurable if progression at the treated site after completion of therapy is clearly documented. * Eastern Cooperative Oncology Group (ECOG) 0-2. * Adequate organ and bone marrow function as defined by: * ANC ≥ 1,500/mm3 (1.5 x 109/L) * Platelets ≥ 100,000/mm3 (100 x 109/L) * Serum creatinine ≤ 1.5 x ULN or estimated creatinine clearance ≥60 ml/min as calculated using the method standard for the institution; * Total serum bilirubin ≤ 1.5 x ULN (\<3 ULN if Gilbert's disease). * Patient must agree to provide tumour tissue from the most recent pathological tumour specimen. * Patient is able (i.e. sufficiently fluent) and willing to complete the quality of life questionnaires in either English or French * Patient consent must be appropriately obtained in accordance with applicable local and regulatory requirements. Each patient must sign a consent form prior to enrollment in the trial to document their willingness to participate * Patients must be accessible for treatment and follow up. Patients registered on this trial must be treated and followed at the participating centre. This implies there must be reasonable geographical limits placed on patients being considered for this trial. * In accordance with NCIC CTG policy, protocol treatment is to begin within 2 working days of patient randomization. * Women of childbearing potential must have agreed to use a highly effective contraceptive method. Exclusion Criteria: * Patients with advanced, symptomatic, visceral spread that are at risk of life threatening complication in the short term. * Patients with symptomatic CNS involvement, meningeal or parenchymal, that is uncontrolled or requires steroids. * Prior treatment with any CDK 4/6 inhibitor. * Prior treatment with mTOR inhibitors. * Active second malignancy, regardless of ongoing treatment. * Any concurrent medical condition that in the opinion of the investigator would interfere with the safe administration of the study drug and participation in the study. * Participation in a prior anti-cancer investigational study within 30 days prior to enrollment.

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Conditions

The condition(s) this trial relates to.

breast cancer breast neoplasm estrogen-receptor positive breast cancer

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Breast cancer

Contacts and locations

Locations

Allan Blair Cancer Centre

Regina, Saskatchewan, S4T 7T1, Canada
BCCA - Abbotsford Centre

Abbotsford British Columbia, British Columbia, V2S 0C2, Canada
BCCA - Fraser Valley Cancer Centre

Surrey, British Columbia, V3V 1Z2, Canada
BCCA - Vancouver Cancer Centre

Vancouver, British Columbia, V5Z 4E6, Canada
CHA-Hopital Du St-Sacrement

Québec, Quebec, G1S 4L8, Canada
CHUM - Hopital Notre-Dame

Montreal, Quebec, H2L 4M1, Canada
Cancer Centre of Southeastern Ontario at Kingston

Kingston, Ontario, K7L 5P9, Canada
Centre hospitalier universitaire de Sherbrooke

Sherbrooke, Quebec, J1H 5N4, Canada
Cross Cancer Institute

Edmonton, Alberta, T6G 1Z2, Canada
Dr. H. Bliss Murphy Cancer Centre

St. John's, Newfoundland and Labrador, A1B 3V6, Canada
Hopital du Sacre-Coeur de Montreal

Montreal, Quebec, H4J 1C5, Canada
Juravinski Cancer Centre at Hamilton Health Sciences

Hamilton, Ontario, L8V 5C2, Canada
Lakeridge Health Oshawa

Oshawa, Ontario, L1G 2B9, Canada
Niagara Health System

St. Catharines, Ontario, L2S 0A9, Canada
Ottawa Hospital Research Institute

Ottawa, Ontario, K1H 8L6, Canada
QEII Health Sciences Centre

Halifax, Nova Scotia, B3H 1V7, Canada
Royal Victoria Regional Health Centre

Barrie, Ontario, L4M 6M2, Canada
Stronach Regional Health Centre at Southlake

Newmarket, Ontario, L3Y 2P9, Canada
The Jewish General Hospital

Montreal, Quebec, H3T 1E2, Canada
The Moncton Hospital

Moncton, New Brunswick, E1C 6Z8, Canada
University Health Network

Toronto, Ontario, M5G 2M9, Canada
Windsor Regional Cancer Centre

Windsor, Ontario, N8W 2X3, Canada

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