Breast CancerNCT05709158
A Study to Learn About the Dangers Linked to Myelosuppression (Decreased Bone Marrow Function) in Breast Cancer Patients Treated With the Study Medicine Palbociclib (Pal Bow Sai Klib)
An observational study of Breast Cancer, run by Pfizer at 1 site in United States.
Trial summary
The purpose of this study is to explore risk factors for grade 4 neutropenia in users of the study medicine Palbociclib for the potential treatment of Palbociclib. This study is seeking participants: treated with the study medicine Palbociclib having any breast cancer records in same month as the initiation date… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Breast Cancer
- How many people
- 4,184 participants
- Where
- 1 siteUnited States
- Study dates
- 19 Aug 2024to 30 Aug 2024
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Breast cancer patients treated with Palbociclib
Who may be able to join
- 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.
Who cannot join
- Having an 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
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Evaluation of Risk Factors Associated With Myelosuppression (Grade 4 Neutropenia) in Breast Cancer Patients Treated With Palbociclib in the Post-marketing Setting: Nested Case-control Study Using the Medical Information Database Network (MID-NET) Database
The purpose of this study is to explore risk factors for grade 4 neutropenia in users of the study medicine Palbociclib for the potential treatment of Palbociclib.
This study is seeking participants:
Read more
- treated with the study medicine Palbociclib
- having any breast cancer records in same month as the initiation date
- having prescription records of palbociclib from 15 December 2017 to 29 February 2024
The study design is a nested case control study. This study design uses de-identified patient data from a hospital based electronic medical record and claim database in Japan. This design was selected since the primary objective is to explore risk factors of Grade 4 neutropenia in users of the study medicine Palbociclib.
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 effect of Palbociclib in decreasing the neutrophil count 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.
Patients who develop grade 4 neutropenia after palbociclib initiation will be matched to controls who do not develop grade 4 neutropenia. A statistical model will be used to explore risk factors of grade 4 neutropenia adjusted for important potential confounding factors.
- Conditions
- Breast Cancer
- Keywords
- Safety, data base study in Japan, Ibrance, Palbociclib, hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-), inoperable or recurrent breast cancer
- Medical subject headings
- Breast Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Case: G4 neutropenia occurs after palbociclib initiation | Grade 4 neutropenia occurs after initiation of palbociclib Note that: Case patients are categorized as control before incurring grade 4 neutropenia | |
| Control: G4 neutropenia does not occur after palbociclib initiation | Grade 4 neutropenia does not occur after initiation of palbociclib |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of Participants With Risk Factors for Grade 4 Neutropenia in Users of Palbociclib
Grade 4 neutropenia, as the outcome of this study, will be defined as an absolute neutrophil count (ANC) of less than 0.5 × 109 cells/L or less than 500 cells/mL during the "on-treatment" period.
Measured: 01 Jun 2017 through 29 Feb 2024
Secondary outcomes (1)
Number of Participants With Risk Factors 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 × 109 cells/L or less than 500 cells/mL during the "on-treatment" period.
Measured: 20 Dec 2016 through 29 Feb 2024
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Feb 2023
- Study start19 Aug 2024
- Primary completion30 Aug 2024
- Study completion30 Aug 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Breast CancerStudies of the same condition, open and under way.
- More trials run by PfizerThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Other
- Enrolment
- 4,184 participants (actual)
Sponsor and investigators
- Lead sponsor
- Pfizer
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Pfizer CT.gov Call Center, Study director, Pfizer
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05709158
- Sponsor's protocol ID
- A5481093
- Other IDs
- NCT05709158
- Status last verified
- Nov 2025
- First submitted
- 24 Jan 2023
- Last updated
- 2 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- Individual data sharing
- No: 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.
Study at a glance
From the registry record, last updated by the sponsor on 2 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluation of Risk Factors Associated With Myelosuppression (Grade 4 Neutropenia) in Breast Cancer Patients Treated With Palbociclib in the Post-marketing Setting: Nested Case-control Study Using the Medical Information Database Network (MID-NET) Database
- ClinicalTrials.gov ID
- NCT05709158
- Acronym / sponsor ID
- A5481093
- Conditions
- Breast Cancer
- Keywords
- Safety, data base study in Japan, Ibrance, Palbociclib, hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-), inoperable or recurrent breast cancer
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 4,184 participants (actual)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Study start
- 19 Aug 2024 (actual)
- Primary completion
- 30 Aug 2024 (actual)
- Study completion
- 30 Aug 2024 (actual)
- First posted
- 2 Feb 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to explore risk factors for grade 4 neutropenia in users of the study medicine Palbociclib for the potential treatment of Palbociclib.
This study is seeking participants:
- treated with the study medicine Palbociclib
- having any breast cancer records in same month as the initiation date
- having prescription records of palbociclib from 15 December 2017 to 29 February 2024
The study design is a nested case control study. This study design uses de-identified patient data from a hospital based electronic medical record and claim database in Japan. This design was selected since the primary objective is to explore risk factors of Grade 4 neutropenia in users of the study medicine Palbociclib.
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 effect of Palbociclib in decreasing the neutrophil count 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.
Patients who develop grade 4 neutropenia after palbociclib initiation will be matched to controls who do not develop grade 4 neutropenia. A statistical model will be used to explore risk factors of grade 4 neutropenia adjusted for important potential confounding factors.
Study design
- Observational model
- Case-control
- Time perspective
- Other
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Case: G4 neutropenia occurs after palbociclib initiation | – | –Grade 4 neutropenia occurs after initiation of palbociclib Note that: Case patients are categorized as control before incurring grade 4 neutropenia |
| Control: G4 neutropenia does not occur after palbociclib initiation | – | –Grade 4 neutropenia does not occur after initiation of palbociclib |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Breast cancer patients treated with Palbociclib
Key inclusion criteria (2 listed)
- 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.
Key exclusion criteria (2 listed)
- Having an 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Number of Participants With Risk Factors for Grade 4 Neutropenia in Users of Palbociclib
Time frame: 01 Jun 2017 through 29 Feb 2024
Grade 4 neutropenia, as the outcome of this study, will be defined as an absolute neutrophil count (ANC) of less than 0.5 × 109 cells/L or less than 500 cells/mL during the "on-treatment" period.
1 secondary outcome
Number of Participants With Risk Factors for Grade 4 Neutropenia in New Users of Palbociclib
Time frame: 20 Dec 2016 through 29 Feb 2024
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 2 Jun 2026.
- To obtain contact information for a study center near you, click here.Link provided by the sponsor.
- Individual participant dataSharing planned: No. 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.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Pfizer CT.gov Call Center study director
Pfizer
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Breast Cancer, run by Pfizer at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 2 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of Participants With Risk Factors for Grade 4 Neutropenia in Users of Palbociclib (time frame: 01 Jun 2017 through 29 Feb 2024). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 2 Jun 2026.