NCT06703606RecruitingPhase 1
A Study to Learn About How Changing Therapy From Emicizumab to Marstacimab Affects People With the Severe Hemophilia A.
A PHASE 1B OPEN-LABEL NON-RANDOMIZED STUDY TO ASSESS THE SAFETY, PHARMACOKINETICS, AND PHARMACODYNAMICS OF MARSTACIMAB TREATMENT FOLLOWING THE DISCONTINUATION OF EMICIZUMAB THERAPY IN ADOLESCENT AND ADULT PARTICIPANTS WITH SEVERE HEMOPHILIA A WITHOUT INHIBITORS.
Source: ClinicalTrials.gov · Last updated 15 Oct 2026
Brief summary (registry, in English)
The purpose of the study is to learn about safety, how the body processes marstacimab and how it works in patients with severe hemophilia A without inhibitors. Hemophilia A is rare bleeding disorder where the blood doesn't clot normally. This causes a person to bleed a lot, even from a small cut. These patients who are on emicizumab medicine for routine prophylaxis for at least 6 months, and desire to switch to marstacimab medicine. Inhibitors are antibodies that the immune system develops because it sees the infused clotting factor as a foreign substance that needs to be destroyed. Antibodies are proteins that eat up the activated factor before it has time to stop the bleeding. Prophylaxis are preventive medicines. This study is seeking for participants: * with severe Hemophilia A withouth inhibitors who are on emicizumab treatment for at least 6 months. * must be 12 to less than 75 years old * must have a body weight of at least 35 kilograms. The results from this study will serve as a guide to doctors and their hemophilia A patients who will change their medicines in the real-world clinical setting. Patients who can take part in the study will receive marstacimab medicine as weekly injections under the skin of 150 milligrams for 4 months. Study treatment with marstacimab will be initiated no earlier than 14 days after last dose of emicizumab. The study can last up to 6 months. The sponsor will provide marstacimab. Patients will continue their usual treatment with the infused clotting factor for their bleeds when taking part in the study. Roll-over into an optional study treatment extension period will be available to participants who wish to continue prophylaxis with marstacimab in countries where it is not commercially available.
- Status (registry)
- Recruiting
- Phase (registry)
- Phase 1
- Study type
- Interventional
- Enrollment
- 15 (estimated)
- First submitted
- 21 Nov 2024
- Start date
- 13 May 2025
- Primary completion date
- 5 May 2027
- Lead sponsor
- Pfizer
- Diseases
- Haemophilia
- NCT number
- NCT06703606
What you commit to
- Study type: Interventional · Phase 1
- Planned participants: 15
- From 13 May 2025 to the primary completion date, 5 May 2027
- 10 sites in 3 countries
- Visits and tests: ask the trial team, the registry does not list them
Built from the registry fields of ClinicalTrials.gov. It describes the study, not your situation.
Who cannot take part
Copied verbatim from ClinicalTrials.gov and grouped by topic. Only the trial team decides who can take part.
Prior treatment
- Previous or current treatment for or history of coronary artery diseases, venous or arterial thrombosis, or ischemic disease.
- Current use of any prohibited concomitant medication(s) or unwillingness or inability to use a required concomitant medication(s).
- Previous administration of an investigational product (drug or vaccine) within 30 days or 5 half-lives preceding the first dose of study intervention used in this study (whichever is longer). Participation in studies of other investigational products (drug or vaccine) at any time during participation in this study.
- Known planned surgical procedure.
Other illness
- Hypersensitivity or allergic reaction to hamster protein or other components of the study intervention.
Lab values
- Any medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study.
- Platelet count \<100,000/μl or hemoglobin \<10 g/dL.
- Clinically significant renal or hepatic function abnormality based on laboratory results at screening, or known kidney or liver disease.
- CD4 cell count ≤200/μl if HIV positive.
Other
- Known hemostatic defect other than hemophilia A.
- Screening 12-lead ECG that demonstrates clinically significant abnormalities that, in the opinion of the investigator, may affect participant safety or interpretation of study results.
- Investigator site staff directly involved in the conduct of the study and their family members, site staff otherwise supervised by the investigator, and sponsor and sponsor-delegate employees directly involved in the conduct of the study and their family members.
Who the study is looking for
- Male and 12 to \<75 years of age with a minimum body weight of 35 kg at the time of signing the informed consent.
- Diagnosis of severe hemophilia A (FVIII activity \<1%) without inhibitors.
- On emicizumab therapy at a standard clinical dose for ≥6 months.
Age in the registry: 12 years to 74 years · Sex: Male · Does not accept healthy volunteers
Sites (10)
Sites in registry order. Pick your city on the disease page to sort them by distance.
| Site | City | Country | Site status |
|---|---|---|---|
| K J Somaiya Hospital & Research Centre Coordinator of this site? Confirm its status | Mumbai | India | Recruiting |
| Nirmal Hospital Pvt Ltd. Coordinator of this site? Confirm its status | Surat | India | Recruiting |
| ECU Health Medical Center Coordinator of this site? Confirm its status | Greenville | United States | Recruiting |
| Brody School of Medicine at East Carolina University Coordinator of this site? Confirm its status | Greenville | United States | Recruiting |
| Altman Clinical and Translational Research Institute-IDS Coordinator of this site? Confirm its status | La Jolla | United States | Not yet recruiting |
| Altman Clinical and Translational Research Institute Coordinator of this site? Confirm its status | La Jolla | United States | Not yet recruiting |
| Orthopaedic Institute for Children/Orthopaedic Hemophilia Treatment Center Coordinator of this site? Confirm its status | Los Angeles | United States | Recruiting |
| UCSD Center for Bleeding and Clotting Disorders Coordinator of this site? Confirm its status | San Diego | United States | Not yet recruiting |
| Ege University Faculty of Medicine Dean's Office Coordinator of this site? Confirm its status | Bornova | Turkey (Türkiye) | Recruiting |
| Istanbul Universitesi Tıp Fakultesi Onkoloji Enstitusu Coordinator of this site? Confirm its status | Fatih | Turkey (Türkiye) | Recruiting |
This page is information, not medical advice. Discuss any trial with your doctor.