Study to Evaluate Overall Survival in Japanese Patients With HR+/HER2- Advanced Breast Cancer Treated With Palbociclib Plus Letrozole

November 22, 2025 updated by: Pfizer

Retrospective, Multicenter, Observational Study to Evaluate Overall Survival in Japanese Patients With HR+/HER2- Advanced Breast Cancer Treated With Palbociclib Plus Letrozole

This is a retrospective, multicenter, observational study in Japan. The primary objective is to evaluate overall survival (OS) in Japanese patients with HR+/HER2- advanced breast cancer who have been treated with palbociclib plus letrozole. This observational study was planned as follow-up study of Japanese phase 2 study of palbociclib (NCT01684215, phase 2 portion of A5481010 study).

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Observational

Enrollment (Actual)

42

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

  • Japan
      • Fukuoka, Japan, 811-1395
        • National Hospital Organization Kyushu Cancer Center
      • Kagoshima, Japan, 892-0833
        • Hakuaikai Medical Corporation Sagara Hospital
      • Kumamoto, Japan, 862-8655
        • Kumamoto Shinto General Hospital
      • Kyoto, Japan, 606-8507
        • Kyoto University Hospital
      • Nagoya, Japan, 464-8681
        • Aichi Cancer Center
      • Osaka, Japan, 540-0006
        • National Hospital Organization - Osaka National Hospital - Institute For Clinical Research
    • Chiba
      • Chiba, Chiba, Japan, 260-8717
        • Chiba Cancer Center
    • Ehime
      • Matsuyama, Ehime, Japan, 791-0280
        • National Hospital Organization Shikoku Cancer Center
    • Hiroshima
      • Hiroshima, Hiroshima, Japan, 730-8518
        • Hiroshima City Hiroshima Citizens Hospital
    • Hokkaido
      • Sapporo, Hokkaido, Japan, 003-0804
        • National Hospital Organization Hokkaido Cancer Center
    • Kumamoto
      • Kumamoto, Kumamoto, Japan, 860-8556
        • Kumamoto University Hospital
    • Saitama
      • Kita-adachi-gun, Saitama, Japan, 362-0806
        • Saitama Cancer Center
    • Tokyo
      • Chuo-ku, Tokyo, Japan, 104-0045
        • National Cancer Center Hospital

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

20 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Patients who participated, treated with palbociclib plus letrozole, and under follow-up for survival in J-Ph2

Description

Inclusion Criteria:

  1. Participated, treated with palbociclib plus letrozole in J-Ph2, and was under follow-up for survival at the study completion of J-Ph2.
  2. For patients who are still alive and have routine visits to the study site, evidence of a personally signed and dated informed consent document indicating that the patient has been informed of all pertinent aspects of the study. For patients who are still alive and had been transferred to another hospital, evidence that the patient has been informed of all pertinent aspects of the study and oral or written informed consent is obtained. For patients who had already passed away, the conduct of this study will be disclosed, and the patients' legally acceptable representatives will be guaranteed an opportunity to refuse data collection for the patients in accordance with the Ethical Guidelines for Medical and Health Research Involving Human Subjects

Exclusion Criteria:

1. There are no exclusion criteria for this study.

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

  • Observational Models: Cohort
  • Time Perspectives: Retrospective

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Overall Survival (OS)
Time Frame: From the date of the first dose of the treatment in study A5481010 to the date of any-cause death or censoring date (maximum of 103.16 months of follow-up); data collected and observed retrospectively over 32 months in A5481154 study
OS was defined as the time from the date of the first dose of the investigational product in Japanese Phase 2 study (A5481010) to the date of any-cause death. In the absence of confirmation of death, survival time was censored to last date the participant was known to be alive. Kaplan-Meier method was used for analysis.
From the date of the first dose of the treatment in study A5481010 to the date of any-cause death or censoring date (maximum of 103.16 months of follow-up); data collected and observed retrospectively over 32 months in A5481154 study

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Percentage of Participants According to Types and Line of Subsequent Treatment
Time Frame: From start of subsequent treatment in study A5481010 until date of death, withdrawal of consent or end of study (maximum of 103.16 months of follow-up); data collected and observed retrospectively over 32 months in A5481154 study
Participants were classified based on types of subsequent treatment and by line of subsequent treatment. Subsequent treatments included: endocrine therapy-based, chemotherapy-based and others (Investigational drug + Endocrine therapy/Chemotherapy).
From start of subsequent treatment in study A5481010 until date of death, withdrawal of consent or end of study (maximum of 103.16 months of follow-up); data collected and observed retrospectively over 32 months in A5481154 study
Duration of Subsequent Therapy by Line of Therapy
Time Frame: From start of subsequent treatment in study A5481010 until date of death, withdrawal of consent or end of study (maximum of 103.16 months of follow-up); data collected and observed retrospectively over 32 months in A5481154 study
Duration of subsequent therapy defined as time from the start date to the end date of each line of treatment among participants who received subsequent treatment. Kaplan-Meier method was used.
From start of subsequent treatment in study A5481010 until date of death, withdrawal of consent or end of study (maximum of 103.16 months of follow-up); data collected and observed retrospectively over 32 months in A5481154 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)

February 3, 2021

Primary Completion (Actual)

September 29, 2023

Study Completion (Actual)

September 29, 2023

Study Registration Dates

First Submitted

January 28, 2021

First Submitted That Met QC Criteria

January 28, 2021

First Posted (Actual)

February 3, 2021

Study Record Updates

Last Update Posted (Estimated)

December 9, 2025

Last Update Submitted That Met QC Criteria

November 22, 2025

Last Verified

November 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • A5481154
  • NCT04735367 (Registry Identifier: ClinicalTrials.gov)

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

No

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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