Real-world Treatment Patterns of Endocrine Based Therapy Among Patients With Hormone Receptor-positive/Human Epidermal Growth Factor Receptor-2-negative (HR+/HER2-) Advanced Breast Cancer: An Analysis of Administrative Claims Data in Japan

An observational study of Breast Cancer, run by Pfizer at 1 site in Japan.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Trial summary

This is a retrospective observational study focusing on patients diagnosed with advanced breast cancer(ABC) in Japan using de-identified claim data from Medical Data Vision (MDV) database. Read more about this study

Who is it for?: Any age
Conditions the study is for: Breast Cancer
How many people: 1,170 participants
Where: 1 siteJapan
Study dates: 31 Aug 2019to 30 Jun 2021
Phase: Observational
Are there results?: Yes, posted in the registrySummary in the doctors' view

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 Any age
All sexes
No healthy volunteers
Child, Adult, Older adult

Study population: Japanese patients with diagnosis of breast cancer, diagnosis of secondary malignant neoplasm and who received endocrine therapy drugs and who didn't receive anti-HER2 therapy drugs (defined as HR+/HER2- breast cancer) and whose data were registered into the MDV database from April 2008

Who may be able to join

Diagnosis of breast cancer based on International statistical classification of diseases and related health problems 10th revision (International Statistical Classification of Diseases and Related Health Problems [ICD-10]) (C50.xx)
Received at least one prescription of endocrine therapy drugs
Diagnosis of secondary malignant neoplasm based on ICD-10 (C77.x, C78.x, C79.x )

Who cannot join

-Received a prescription of anti-HER2 therapy (Trastuzumab, Trastuzumab emtansine, Pertuzumab, and Lapatinib tosilate hydrate)

Trial locations and contacts

1 site in 1 country.

Japan1 site

Pfizer Japan
Tokyo

Other trials in Japan

About this study

Official title: Descriptive Analyses of Clinical Characteristics and Treatment Patterns of Breast Cancer Patients Initiating Palbociclib (Ibrance(Registered)) Treatment in Japan by Using MDV Database

This is a retrospective observational study focusing on patients diagnosed with advanced breast cancer(ABC) in Japan using de-identified claim data from Medical Data Vision (MDV) database.

The primary objective of this study is to describe patient demographics, treatment patterns and treatment duration of palbociclib, and subsequent treatment patterns and treatment duration after palbociclib-based therapy among ABC patients in Japan The secondary objective of the study is to describe patient demographics, treatment patterns of ABC patients and treatment duration of endocrine therapy, and subsequent treatment patterns and treatment duration after endocrine therapy among ABC patients in Japan.

Conditions: Breast Cancer
Keywords: Advanced breast cancer, Hormone receptor positive (HR+), Human Epidermal Growth Factor Receptor 2 Negative (HER2-)
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 groups in NCT05153187
Study group	Role	What they receive
Patients with HR+/HER2- advanced breast cancer		Not described

What is being measured

The primary outcome is the main question the study is designed to answer.

Percentage of Participants According to Number of Blood Tests at 1 to 4 Weeks From Palbociclib Treatment Initiation
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 1 to 4 weeks after administration of palbociclib is reported in this outcome measure.
Measured: Anytime between 1 to 4 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Percentage of Participants According to Number of Blood Tests at 5 to 8 Weeks From Palbociclib Treatment Initiation
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 5 to 8 weeks after administration of palbociclib is reported in this outcome measure.
Measured: Anytime between 5 to 8 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Percentage of Participants According to Number of Blood Tests at 9 to 12 Weeks From Palbociclib Treatment Initiation
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 9 to 12 weeks after administration of palbociclib is reported in this outcome measure.
Measured: Anytime between 9 to 12 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Percentage of Participants According to Number of Blood Tests at 13 to 16 Weeks From Palbociclib Treatment Initiation
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 13 to 16 weeks after administration of palbociclib is reported in this outcome measure.
Measured: Anytime between 13 to 16 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Percentage of Participants According to Number of Blood Tests at 17 to 20 Weeks From Palbociclib Treatment Initiation
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 17 to 20 weeks after administration of palbociclib is reported in this outcome measure.
Measured: Anytime between 17 to 20 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Time to Treatment Failure of Palbociclib
Time to treatment failure of palbociclib was defined as time from the date of first palbociclib prescription to the date of lost to follow-up or to the date of the next line of therapy, defined as the end of palbociclib treatment. Time to treatment failure of palbociclib was censored at participant disenrollment or end of study period.
Measured: From start of palbociclib treatment until end of palbociclib treatment or censoring date (maximum up to 42.5 months); available data observed retrospectively over approximately 22 months in this study

Secondary outcomes (3)

Mean Palbociclib Daily Dose
Measured: From start of palbociclib treatment until end of palbociclib treatment or end of study period (maximum up to 42.5 months); available data observed retrospectively over approximately 22 months in this study
Number of Participants According to Regimen of First Subsequent Therapy After End of Palbociclib
Number of participants according to regimen of first subsequent therapy after end of palbociclib at first line and second line are reported in this outcome measure. The regimen was defined as any breast cancer treatment(s) received within 30 days of earlier treatment initiation. Only regimens used by >=3 participants in participants treated with palbociclib in the first or second line settings were reported. One participant may be included in more than one regimen.
Measured: From first subsequent therapy until end of study period (maximum up to 38.1 months); available data observed retrospectively over approximately 22 months in this study
Time to Treatment Failure of Subsequent Therapy After End of Palbociclib
Time to treatment failure of subsequent therapy after palbociclib was defined as time from the date of first next line of therapy after end of palbociclib treatment to the date of lost to follow-up or to the date of the second next line of therapy. Time to treatment failure was censored at participant disenrollment or end of study period.
Measured: From start of first subsequent therapy until date of lost to follow-up or date of next line of therapy or censoring date (maximum up to 38.1 months); available data observed retrospectively over approximately 22 months in this study

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

31 Aug 201930 Jun 2021

First posted10 Dec 2021
Study start31 Aug 2019
Primary completion30 Jun 2021
Study completion30 Jun 2021

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
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: Cohort
Time perspective: Retrospective
Enrolment: 1,170 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT05153187
Sponsor's protocol ID: A5481115
Other IDs: NCT05153187
Status last verified: Mar 2026
First submitted: 29 Nov 2021
Last updated: 21 Apr 2026
Results posted: Yes, on ClinicalTrials.gov
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.

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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All Breast Cancer trials

Study at a glance

From the registry record, last updated by the sponsor on 21 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Descriptive Analyses of Clinical Characteristics and Treatment Patterns of Breast Cancer Patients Initiating Palbociclib (Ibrance(Registered)) Treatment in Japan by Using MDV Database
ClinicalTrials.gov ID: NCT05153187
Acronym / sponsor ID: A5481115
Conditions: Breast Cancer
Keywords: Advanced breast cancer, Hormone receptor positive (HR+), Human Epidermal Growth Factor Receptor 2 Negative (HER2-)
Study type: Observational
Recruitment status: Completed
Enrolment: 1,170 participants (actual)
Lead sponsor: PfizerIndustry (pharma, biotech, devices)
Study start: 31 Aug 2019 (actual)
Primary completion: 30 Jun 2021 (actual)
Study completion: 30 Jun 2021 (actual)
First posted: 10 Dec 2021 (actual)
Results: Posted 21 Apr 2026

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

This is a retrospective observational study focusing on patients diagnosed with advanced breast cancer(ABC) in Japan using de-identified claim data from Medical Data Vision (MDV) database.

Study design

Observational model: Cohort
Time perspective: Retrospective
Number of arms: 1

Arm	Type	Receives
Patients with HR+/HER2- advanced breast cancer	–	–

Who may qualify

Sex: All
Healthy volunteers: Not accepted
Age groups: Child, Adult, Older adult
Study population: Japanese patients with diagnosis of breast cancer, diagnosis of secondary malignant neoplasm and who received endocrine therapy drugs and who didn't receive anti-HER2 therapy drugs (defined as HR+/HER2- breast cancer) and whose data were registered into the MDV database from April 2008

Key inclusion criteria (3 listed)

Diagnosis of breast cancer based on International statistical classification of diseases and related health problems 10th revision (International Statistical Classification of Diseases and Related Health Problems [ICD-10]) (C50.xx)
Received at least one prescription of endocrine therapy drugs
Diagnosis of secondary malignant neoplasm based on ICD-10 (C77.x, C78.x, C79.x )

Key exclusion criteria (1 listed)

-Received a prescription of anti-HER2 therapy (Trastuzumab, Trastuzumab emtansine, Pertuzumab, and Lapatinib tosilate hydrate)

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

Percentage of Participants According to Number of Blood Tests at 1 to 4 Weeks From Palbociclib Treatment Initiation
Time frame: Anytime between 1 to 4 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 1 to 4 weeks after administration of palbociclib is reported in this outcome measure.
Percentage of Participants According to Number of Blood Tests at 5 to 8 Weeks From Palbociclib Treatment Initiation
Time frame: Anytime between 5 to 8 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 5 to 8 weeks after administration of palbociclib is reported in this outcome measure.
Percentage of Participants According to Number of Blood Tests at 9 to 12 Weeks From Palbociclib Treatment Initiation
Time frame: Anytime between 9 to 12 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 9 to 12 weeks after administration of palbociclib is reported in this outcome measure.
Percentage of Participants According to Number of Blood Tests at 13 to 16 Weeks From Palbociclib Treatment Initiation
Time frame: Anytime between 13 to 16 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 13 to 16 weeks after administration of palbociclib is reported in this outcome measure.
Percentage of Participants According to Number of Blood Tests at 17 to 20 Weeks From Palbociclib Treatment Initiation
Time frame: Anytime between 17 to 20 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study
Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and >=5) at 17 to 20 weeks after administration of palbociclib is reported in this outcome measure.
Time to Treatment Failure of Palbociclib
Time frame: From start of palbociclib treatment until end of palbociclib treatment or censoring date (maximum up to 42.5 months); available data observed retrospectively over approximately 22 months in this study
Time to treatment failure of palbociclib was defined as time from the date of first palbociclib prescription to the date of lost to follow-up or to the date of the next line of therapy, defined as the end of palbociclib treatment. Time to treatment failure of palbociclib was censored at participant disenrollment or end of study period.

3 secondary outcomes

Mean Palbociclib Daily Dose
Time frame: From start of palbociclib treatment until end of palbociclib treatment or end of study period (maximum up to 42.5 months); available data observed retrospectively over approximately 22 months in this study
Number of Participants According to Regimen of First Subsequent Therapy After End of Palbociclib
Time frame: From first subsequent therapy until end of study period (maximum up to 38.1 months); available data observed retrospectively over approximately 22 months in this study
Time to Treatment Failure of Subsequent Therapy After End of Palbociclib
Time frame: From start of first subsequent therapy until date of lost to follow-up or date of next line of therapy or censoring date (maximum up to 38.1 months); available data observed retrospectively over approximately 22 months in this study

Results and safety

Results posted to the registry on 21 Apr 2026, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Participants With HR+/HER- Breast Cancer	1,170	1,170

Primary outcome: Percentage of Participants According to Number of Blood Tests at 1 to 4 Weeks From Palbociclib Treatment Initiation

Time frame: Anytime between 1 to 4 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study. Number. Unit: Percentage of participants

Measure	Participants With HR+/HER- Breast Cancer n = 1074
0	17.4
1	12.9
2	28.4
3	29.7
4	8.3
>=5	3.3

Population analysed: All eligible participants who were enrolled and whose data was included in the study. Here, "Overall Number of Participants Analyzed" signifies number of participants evaluable for this outcome measure.

Primary outcome: Percentage of Participants According to Number of Blood Tests at 5 to 8 Weeks From Palbociclib Treatment Initiation

Time frame: Anytime between 5 to 8 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study. Number. Unit: Percentage of participants

Measure	Participants With HR+/HER- Breast Cancer n = 1074
0	23.6
1	25.5
2	38.5
3	9.3
4	2.1
>=5	1.0

Primary outcome: Percentage of Participants According to Number of Blood Tests at 9 to 12 Weeks From Palbociclib Treatment Initiation

Time frame: Anytime between 9 to 12 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study. Number. Unit: Percentage of participants

Measure	Participants With HR+/HER- Breast Cancer n = 1016
0	27.6
1	32.6
2	31.1
3	6.1
4	1.4
>=5	1.3

Primary outcome: Percentage of Participants According to Number of Blood Tests at 13 to 16 Weeks From Palbociclib Treatment Initiation

Time frame: Anytime between 13 to 16 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study. Number. Unit: Percentage of participants

Measure	Participants With HR+/HER- Breast Cancer n = 962
0	31.8
1	37.9
2	22.1
3	5.7
4	1.4
>=5	1.0

3 secondary outcomes are reported in the full results.

Adverse events

Time frame: Not applicable as all-cause mortality and adverse events were not monitored and evaluated for the study.. Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Participants With HR+/HER- Breast Cancer	0 of 0	0 of 0	0

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 21 Apr 2026.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
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 Japan.

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 3 inclusion and 1 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 21 Apr 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 Japan. 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?

Yes. Results are posted in the registry (first posted 21 Apr 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

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?

Percentage of Participants According to Number of Blood Tests at 1 to 4 Weeks From Palbociclib Treatment Initiation (time frame: Anytime between 1 to 4 weeks from palbociclib treatment initiation; available data observed retrospectively over approximately 22 months in this study). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05153187.

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 21 Apr 2026.