Study to Compare Overall Survival in Medicare Patients With Metastatic Breast Cancer Treated With a Medicine Called Palbociclib in Combination With Aromatase Inhibitor and Aromatase Inhibitor by Itself.

November 3, 2025 updated by: Pfizer

Comparative Assessment of Overall Survival in Medicare Patients With HR+/HER2- Metastatic Breast Cancer Treated With Palbociclib in Combination With Aromatase Inhibitor (AI vs. AI Alone)

A retrospective study of de-identified (to preserve patient privacy) patient information from the SEER-Medicare Database to compare overall survival of first line palbociclib + aromatase inhibitor (AI) therapy versus AI therapy alone treatment in women or men aged 65 and older with newly diagnosed hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) metastatic breast cancer (MBC) in the United States

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Observational

Enrollment (Actual)

779

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • New York
      • New York, New York, United States, 10001
        • Pfizer New York

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Medicare recipients with HR+/HER2- with De Novo metastatic breast cancer

Description

Inclusion Criteria:

  • De novo metastatic (stage IV) disease at initial breast cancer diagnosis during 2015-2019
  • HR+/HER2- molecular subtype at diagnosis
  • Initiated 1L systemic therapy with palbociclib + AI or AI alone

Exclusion Criteria:

  • Patients will be excluded if their metastatic breast cancer diagnosis was first recorded in a death certificate or at the time of autopsy.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Palbociclib + AI
Adult metastatic breast cancer patients who initiated Palbociclib + an aromatase inhibitor as first line therapy in SEER-Medicare
Drug: Palbociclib
Palbociclib with an aromatase inhibitor therapy
Other Names:
  • Ibrance
Drug: Aromatase Inhibitor
Aromatase Inhibitor Therapy
Other Names:
  • letrozole, anastrozole, exemestane
AI alone
Adult metastatic breast cancer patients who initiated an aromatase inhibitor (alone) as first line therapy
Drug: Aromatase Inhibitor
Aromatase Inhibitor Therapy
Other Names:
  • letrozole, anastrozole, exemestane

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Overall Survival According to Unadjusted Analysis
Time Frame: From index date to death (approximately 69.9 months); retrospective data evaluated in 4 months (approximately) of this study
Overall survival was defined as time in months from the study index date to all cause death. Study index date in this outcome measure was the date of first line of treatment initiation with palbociclib + AI or AI alone after the de novo mBC diagnosis. De novo mBC referred to breast cancer that physician diagnosed for the first time after it had already spread outside of the breast to distant parts of the body. Unadjusted analysis: analysis not considering any covariates, specifically potential differences in baseline characteristics that could confound the association between treatment and survival. Overall survival was assessed using Kaplan-Meier analysis.
From index date to death (approximately 69.9 months); retrospective data evaluated in 4 months (approximately) of this study
Overall Survival According to Stabilized Inverse Probability of Treatment Weighted (sIPTW) Analysis
Time Frame: From index date to death (approximately 69.9 months); retrospective data evaluated in 4 months (approximately) of this study
Overall survival was defined as time in months from the study index date to all cause death. Study index date in this outcome measure was the date of first line of treatment initiation with palbociclib + AI or AI alone after the de novo mBC diagnosis. De novo mBC referred to breast cancer that physician diagnosed for the first time after it had already spread outside of the breast to distant parts of the body. sIPTW analysis: stabilized inverse probability treatment weighting. This is a statistical method that reweights participants to create groups with similar baseline characteristics. The analysis therefore adjusts for differences in baseline characteristics that could confound the association between treatment and survival. Overall survival was assessed using Kaplan-Meier analysis.
From index date to death (approximately 69.9 months); retrospective data evaluated in 4 months (approximately) of this study

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Pfizer

Investigators

  • Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

September 29, 2023

Primary Completion (Actual)

January 24, 2024

Study Completion (Actual)

January 24, 2024

Study Registration Dates

First Submitted

October 11, 2023

First Submitted That Met QC Criteria

October 11, 2023

First Posted (Actual)

October 17, 2023

Study Record Updates

Last Update Posted (Actual)

November 18, 2025

Last Update Submitted That Met QC Criteria

November 3, 2025

Last Verified

November 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • A5481182
  • Henri 3 (Other Identifier: Alias Study Number)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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