HemophiliaNCT07859527
A Study to Learn About the Study Medicine (Called Marstacimab) in People With Hemophilia A or B
An observational study of Hemophilia, run by Pfizer.
Trial summary
The purpose of this non-interventional, observational, real-world study is to find out what are the real-world experiences of people living with hemophilia A or B[OK1.1] who start the study medicine (called marstacimab) in routine clinical practice. Read more about this study
- Who is it for?
- Ages 6 years and older
- Conditions the study is for
- Hemophilia
- What is being tested?
- Marstacimab
- How many people
- 100 participants
- Where
- No sites listed yet
- Study dates
- 5 Oct 2026to 30 Aug 2028
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
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 6 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: This observational study is designed as a virtual-site study to take place in the United States (US), and will collect real-world data from participants' documented routine interactions with the healthcare system, surveys, and interviews. Participants will be recruited from US-based healthcare sites that care for people living with hemophilia, or through digital outreach
Medical record documentation of hematologist-confirmed diagnosis of hereditary factor VIII deficiency disease (Hemophilia A) or hereditary factor IX deficiency disease (Hemophilia B) prior to enrollment
- Current treatment with marstacimab or documentation of a prescription to initiate marstacimab
- Aged 6 or older at the time of consenting into the study
- Receipt of medical care in the United States
- Evidence of a personally signed and dated informed consent document indicating that the participant (or a legally authorized representative) has been informed of all pertinent aspects of the study ○ If the participant is between the ages of 7 and 17, evidence of a personally signed and dated informed assent indicating that the participant has been informed of and assents to the study
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: MARSTACIMAB REAL-WORLD EVALUATION OF EFFECTIVENESS IN HEMOPHILIA: A UNITED STATES MEDICAL RECORD AND PARTICIPANT REPORTED OUTCOME STUDY (MARVL-US)
The purpose of this non-interventional, observational, real-world study is to find out what are the real-world experiences of people living with hemophilia A or B[OK1.1] who start the study medicine (called marstacimab) in routine clinical practice. Hemophilia is a rare genetic condition where the blood does not clot normally, meaning people bleed longer than usual after an injury.
This study is seeking participants who are living with hemophilia A or B and:
Read more
- Have a medical record documenting hemophilia A or hemophilia B. A hematologist must have confirmed the diagnosis before they join the study.
- Are under current treatment with marstacimab or have a prescription to start the treatment with marstacimab
- Are 6 years of age or older and the recipient of medical care in the United States All participants in this study will receive their usual treatment for hemophilia A or hemophilia B Participants will take part in this study for 1 year. During this time, they will complete up to six surveys. These surveys will be given between enrollment and about one year after marstacimab is started.
Some participants in the study may be asked to take part in interviews. During these interviews they will be asked about their experience with hemophilia or marstacimab.
The study will provide information about how well the marstacimab treatment works. It will also assess treatment burden, and treatment preferences. This information will help to determine its benefit compared to existing treatment options. It will also help doctors make treatment decisions and optimize hemophilia care.
- Conditions
- Hemophilia
- Being tested
- Marstacimab
- Keywords
- Hemophilia; hemophilia A; hemophilia B; real world evidence; real world data; electronic medical records; registry; marstacimab.
- Medical subject headings
- Hemophilia A, Hemophilia B
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
MarstacimabDrug
As provided in real world practice
| Study group | Role | What they receive |
|---|---|---|
| Real World Data participants | This observational study is designed as a virtual-site study to take place in the United States (US), and will collect real-world data from participants' documented routine interactions with the healthcare system, surveys, and interviews. Participants will be recruited from US-based healthcare sites that care for people living with hemophilia, or through digital outreach Receives: Drug: Marstacimab |
What is being measured
The primary outcome is the main question the study is designed to answer.
Patient reported responses to Marstacimab Patient Preference Survey (MPPS)
Measured: Six months after initiating marstacimab
Secondary outcomes (4)
Patient reported responses to Hemophilia Treatment Experience Measure (Hemo-TEM)
Measured: Month 6 and month 12
Annualized bleed rates (ABRs)
Measured: Baseline through 12 months
ABRs of all bleeding events
Measured: Baseline through 36 months of martstacimab treatment
Reponses to the hemophilia prophylaxis experience survey, second version (HPES-II)
Measured: Baseline to month 3
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Oct 2026
- Study start5 Oct 2026 (estimated)
- Primary completion30 Aug 2028 (estimated)
- Study completion30 Aug 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for HemophiliaStudies 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
- Cross-sectional
- Enrolment
- 100 participants (estimated)
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
- NCT07859527
- Sponsor's protocol ID
- B7841028
- Status last verified
- Sep 2026
- First submitted
- 29 Sep 2026
- Last updated
- 5 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- 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 5 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- MARSTACIMAB REAL-WORLD EVALUATION OF EFFECTIVENESS IN HEMOPHILIA: A UNITED STATES MEDICAL RECORD AND PARTICIPANT REPORTED OUTCOME STUDY (MARVL-US)
- ClinicalTrials.gov ID
- NCT07859527
- Acronym / sponsor ID
- B7841028
- Conditions
- Hemophilia
- Keywords
- Hemophilia; hemophilia A; hemophilia B; real world evidence; real world data; electronic medical records; registry; marstacimab.
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Study start
- 5 Oct 2026 (estimated)
- Primary completion
- 30 Aug 2028 (estimated)
- Study completion
- 30 Aug 2028 (estimated)
- First posted
- 5 Oct 2026 (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 non-interventional, observational, real-world study is to find out what are the real-world experiences of people living with hemophilia A or B[OK1.1] who start the study medicine (called marstacimab) in routine clinical practice. Hemophilia is a rare genetic condition where the blood does not clot normally, meaning people bleed longer than usual after an injury.
This study is seeking participants who are living with hemophilia A or B and:
- Have a medical record documenting hemophilia A or hemophilia B. A hematologist must have confirmed the diagnosis before they join the study.
- Are under current treatment with marstacimab or have a prescription to start the treatment with marstacimab
- Are 6 years of age or older and the recipient of medical care in the United States All participants in this study will receive their usual treatment for hemophilia A or hemophilia B Participants will take part in this study for 1 year. During this time, they will complete up to six surveys. These surveys will be given between enrollment and about one year after marstacimab is started.
Some participants in the study may be asked to take part in interviews. During these interviews they will be asked about their experience with hemophilia or marstacimab.
The study will provide information about how well the marstacimab treatment works. It will also assess treatment burden, and treatment preferences. This information will help to determine its benefit compared to existing treatment options. It will also help doctors make treatment decisions and optimize hemophilia care.
Study design
- Observational model
- Cohort
- Time perspective
- Cross-sectional
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Real World Data participants | – | Drug: MarstacimabThis observational study is designed as a virtual-site study to take place in the United States (US), and will collect real-world data from participants' documented routine interactions with the healthcare system, surveys, and interviews. Participants will be recruited from US-based healthcare sites that care for people living with hemophilia, or through digital outreach |
Who may qualify
- Ages
- 6 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- This observational study is designed as a virtual-site study to take place in the United States (US), and will collect real-world data from participants' documented routine interactions with the healthcare system, surveys, and interviews. Participants will be recruited from US-based healthcare sites that care for people living with hemophilia, or through digital outreach
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| MarstacimabAs provided in real world practice | Drug | Real World Data participants |
Primary outcome
Patient reported responses to Marstacimab Patient Preference Survey (MPPS)
Time frame: Six months after initiating marstacimab
4 secondary outcomes
Patient reported responses to Hemophilia Treatment Experience Measure (Hemo-TEM)
Time frame: Month 6 and month 12
Annualized bleed rates (ABRs)
Time frame: Baseline through 12 months
ABRs of all bleeding events
Time frame: Baseline through 36 months of martstacimab treatment
Reponses to the hemophilia prophylaxis experience survey, second version (HPES-II)
Time frame: Baseline to month 3
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Oct 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.
Pfizer CT.gov Call Center study director
Pfizer
Questions about this trial
What is this clinical trial studying?
An observational study of Hemophilia, run by Pfizer.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
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: opening soon, as of the sponsor's last update on 5 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Pfizer CT.gov Call Center (1-800-718-1021, ClinicalTrials.gov_Inquiries@pfizer.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Patient reported responses to Marstacimab Patient Preference Survey (MPPS) (time frame: Six months after initiating marstacimab). 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 5 Oct 2026.