A Study to Understand About the Study Medicine Palbociclib in Breast Cancer Patients After it is Out in the Japanese Market

Ibrance® Post-Marketing Database Study Incidence of Interstitial Lung Disease in Inoperable or Recurrent Breast Cancer Patients Treated With Palbociclib in a Post-marketing Setting: Cohort Study Using the Medical Data Vision (MDV) Database

The purpose of the study is to:

• compare the chances of getting interstitial lung disease (ILD) in new users of palbociclib plus fulvestrant to new users of fulvestrant alone (using data from before palbociclib was out in the market)
• look into the factors that can cause ILD in new users of palbociclib.

This study uses patient data without giving out any personal information of the patient. This data is taken from a hospital-based claims database of the MDV database, that includes data from more than 400 hospitals in Japan.

This study will use data of patients who are:

• diagnosed with breast cancer that include newly treated with palbociclib and/or other endocrine-based therapies for inoperable or recurrent breast cancer between 25 November 2011 and 30 November 2024.

Study Overview

• Status: Completed
• Conditions: Breast Neoplasms
• Intervention / Treatment: Drug: palbociclib plus fulvestrant; Drug: fulvestrant

• Study Type: Observational
• Enrollment (Actual): 1772

Contacts and Locations

Study Locations

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

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

The source population comprises patients diagnosed with breast cancer that include newly treated with palbociclib and/or other endocrine-based therapies for inoperable or recurrent breast cancer between 25 November 2011 and 31 December 2024

Description

Inclusion Criteria:

• Having prescription records of drugs for endocrine therapy (aromatase inhibitors, SERDs, SERMs, and CDK4/6 inhibitors) from 25 November 2011 to 31 December 2024.
• Having any breast cancer records with definitive diagnosis in the same month as the first prescription date.
• Having any records in MDV database on or before 6 months prior to the first prescription date (<= -180 days: first prescription date = 0 day).
• Having any records in MDV database within 6 months prior to the first prescription date (-180 days to 0 day).

Exclusion Criteria:

• Having any records of anti-HER2 medication (e.g., trastuzumab, pertuzumab, lapatinib or trastuzumab emtansine) from 25 November 2011 to 31 December 2024.
• Having any records of second primary cancer with definitive diagnosis

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
New prescription of palbociclib with fulvestrant.; Patients treated with the combination of palbociclib and fulvestrant	Drug: palbociclib plus fulvestrant; Patients treated with the combination of palbociclib and fulvestrant; Other Names: Ibrance; fulvestrant; Drug: fulvestrant; Patients treated with fulvestrant alone
New prescription of fulvestrant monotherapy before the launch of palbociclib; Patients treated with fulvestrant alone	Drug: fulvestrant; Patients treated with fulvestrant alone

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
The hazard ratios of ILD in palbociclib plus fulvestrant to new users of fulvestrant alone	25 November 2011 and 30 September 2024
The rate ratios of ILD in palbociclib plus fulvestrant to new users of fulvestrant alone	25 November 2011 and 30 September 2024
The rate differences of ILD in palbociclib plus fulvestrant to new users of fulvestrant alone	25 November 2011 and 30 September 2024
The incidence rate of ILD by each risk factor in new users of palbociclib	25 November 2011 and 30 September 2024

Secondary Outcome Measures

Outcome Measure	Time Frame
The incidence rate of ILD by each risk factor in new users of endocrine-based therapies including combination with CDK4/6 inhibitors	25 November 2011 and 30 September 2024

Collaborators and Investigators

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

Study record dates

Study Major Dates

• Study Start (Actual): January 21, 2025
• Primary Completion (Actual): February 7, 2025
• Study Completion (Actual): February 7, 2025

Study Registration Dates

• First Submitted: July 24, 2025
• First Submitted That Met QC Criteria: July 24, 2025
• First Posted (Actual): July 31, 2025

Study Record Updates

• Last Update Posted (Estimated): August 28, 2025
• Last Update Submitted That Met QC Criteria: August 27, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: inoperable or recurrent breast cancer; Ibrance; palbociclib; Post-Marketing Database Study; Incidence of interstitial lung disease (ILD); Medical Data Vision (MDV)
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms; Hormones; Hormones, Hormone Substitutes, and Hormone Antagonists; Polycyclic Compounds; Steroids; Fused-Ring Compounds; Estradiol; Estrenes; Estranes; Estradiol Congeners; Gonadal Steroid Hormones; Gonadal Hormones; Fulvestrant; palbociclib
• Other Study ID Numbers: A5481117

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 device product: No