A Study to Learn About the Relationship Between Hepatic Impairment and Myelosuppression (Decreased Bone Marrow Function) in Breast Cancer Patients Treated With the Study Medicine Palbociclib (Pal-bow-sai-klib)

Evaluation of Incidence of Myelosuppression (Grade 4 Neutropenia) in Breast Cancer Patients With Mild, Moderate or Severe Hepatic Impairment Treated With Palbociclib Compared to Patients With Reserved Hepatic Function in the Post-marketing Setting: Cohort Study Using the Medical Information Database Network (MID-NET) Database

The purpose of this study is to evaluate incidence of grade 4 neutropenia in patients who have hepatic impairment and use the study medicine Palbociclib.

This study is seeking participants:

• treated with the study medicine Palbociclib
• having any breast cancer records in same month as the index date (the first prescription date)
• having prescription records of palbociclib from 20 December 2016 to 29 February 2024

The study design is a cohort study. This study design uses de-identified patient data from a hospital based electronic medical record and claim database in Japan.

One of the important side effects of taking Palbociclib is neutropenia (decreased count of neutrophils - a type of white blood cell). In this study, the relationship between neutropenia caused by Palbociclib and hepatic impairment was studied after it was released to the market. To do that, the study gathered details of breast cancer patients newly treated with Palbociclib from 23 hospitals and 10 medical institutes across Japan.

The below patient details were collected:

• dose of Palbociclib
• other medicines prescribed for cancer
• age
• gender
• past information on cancer treatments
• laboratory findings at baseline

The result was based on the neutrophil count collected from the laboratory data. Around 1300 patients newly treated with Palbociclib for breast cancer was calculated by the medical information database network (MID-NET) in 6 years from 15 December 2017.

Study Overview

• Status: Completed
• Conditions: Breast Cancer

• Study Type: Observational
• Enrollment (Actual): 733

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

Breast cancer patients treated with Palbociclib

Description

Inclusion Criteria:

• Having prescription records of palbociclib from 15 December 2017 to 29 February 2024.
• Having any breast cancer records in same month as the first prescription date.
• Having laboratory tests and visit records (SS-MIX2) on or before 180 days prior to the first prescription date
• Having SS-MIX2 hospital-visit records within 180 days before the first prescription date

Exclusion Criteria:

• Having an absolute neutrophil count (ANC) less than the threshold value for grade 4 neutropenia within 30 days of the first prescription of palbociclib
• Having any records of anti-HER2 medication

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Cohort; New users of palbociclib for inoperable or recurrent breast cancer divided into 4 groups based on severity levels of hepatic impairment

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants With/Without Hepatic Impairment for Grade 4 Neutropenia in New Users of Palbociclib	Grade 4 neutropenia, as the outcome of this study, will be defined as an ANC of less than 0.5 × 10^9 cells/L or less than 500 cells/mL during the "on-treatment" period.	20 Dec 2016 through 29 Feb 2024

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants With/Without Hepatic Impairment for Grade 3-4 Neutropenia in New Users of Palbociclib	Grade 3-4 neutropenia, as the outcome of this study, will be defined as an ANC of less than 1.0 × 10^9 cells/L or less than 500 cells/mL during the "on-treatment" period.	20 Dec 2016 through 29 Feb 2024

Collaborators and Investigators

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

Study record dates

Study Major Dates

• Study Start (Actual): August 19, 2024
• Primary Completion (Actual): August 30, 2024
• Study Completion (Actual): August 30, 2024

Study Registration Dates

• First Submitted: June 11, 2023
• First Submitted That Met QC Criteria: June 11, 2023
• First Posted (Actual): June 22, 2023

Study Record Updates

• Last Update Posted (Actual): June 13, 2025
• Last Update Submitted That Met QC Criteria: June 10, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: Safety; inoperable or recurrent breast cancer; Palbociclib; Ibrance; hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-); database study in Japan
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Breast Neoplasms
• Other Study ID Numbers: A5481116

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.