Marstacimab for Hemophilia

Recruiting at 70 trial locations

Overseen By Pfizer CT.gov Call Center

Age: Any Age

Sex: Male

Trial Phase: Phase 3

Sponsor: Pfizer

Must be taking: Marstacimab

Must not be taking: Immunomodulatory drugs

Disqualifiers: Coronary artery disease, Thrombosis, Ischemic disease, Abnormal renal function, Unstable hepatic function, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Pivotal Trial (Near Approval) This treatment is in the last trial phase before FDA approval

Prior Safety Data This treatment has passed at least one previous human trial

Approved in 2 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: Unknown

Duration: Up to 7 years

245 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores the long-term safety and effectiveness of marstacimab for individuals with severe hemophilia A or B. Hemophilia is a condition where blood doesn't clot properly, causing excessive bleeding. The study includes those who successfully completed previous related studies without early withdrawal. Participants will receive regular injections of marstacimab to determine if it helps manage their condition over time. This trial suits those with severe hemophilia who participated in prior studies without major issues. As a Phase 3 trial, it represents the final step before FDA approval, offering participants a chance to contribute to the potential availability of a new treatment.

Will I have to stop taking my current medications?

The trial requires that you do not use certain medications like immunomodulatory drugs (e.g., IVIG, routine systemic corticosteroids, rituximab) and FVIII or FIX replacement during the study. If you are on these medications, you may need to stop them to participate.

Is there any evidence suggesting that marstacimab is likely to be safe for humans?

Research has shown that marstacimab is generally safe for people with hemophilia. Previous studies demonstrated its safety and effectiveness in adults with severe hemophilia A and B. The FDA has approved marstacimab for regular use to help prevent bleeding episodes in adults, confirming its safety for humans.

In clinical trials, some patients experienced mild side effects, but serious issues were rare. Data from these studies suggest that marstacimab is a promising and safe treatment option for managing hemophilia. ^{1 2 3 4 5}

Why do researchers think this study treatment might be promising for hemophilia?

Marstacimab is unique because it offers a new way to manage hemophilia through subcutaneous injections, which could be more convenient compared to the intravenous methods used in many current treatments. Unlike standard factor replacement therapies, marstacimab works by targeting tissue factor pathway inhibitor (TFPI), a different mechanism that aims to improve blood clotting. Researchers are excited about marstacimab because it could provide more flexible dosing options and potentially improve quality of life for people with hemophilia.

What evidence suggests that marstacimab might be an effective treatment for hemophilia?

Research shows that marstacimab, which participants in this trial will receive, helps reduce bleeding episodes in people with hemophilia A and B. Studies have found that regular use of marstacimab can significantly lower the number of bleeding incidents each year. This medication targets a specific protein to help blood clot properly. Marstacimab has proven effective even for patients with inhibitors, substances that can complicate treatment. Overall, evidence suggests marstacimab is a promising option for managing hemophilia. ^{1 2 3 6 7}

Who Is on the Research Team?

Pfizer CT.gov Call Center

Principal Investigator

Pfizer

Are You a Good Fit for This Trial?

This trial is for adolescents and adults aged 12 to <75 with severe hemophilia A or B, weighing at least 35 kg, who completed a prior study without early termination. It's not for those planning surgery, with unstable HIV or liver function, abnormal kidney function, using certain immune treatments, or having a history of significant heart or blood vessel problems.

Inclusion Criteria

Participants have successfully completed participation in study B7841005, defined as did not require "Early Termination" from study B7841005

I weigh at least 35 kg.

Exclusion Criteria

I am currently using or plan to use immune tolerance therapy for my condition.

You cannot participate in this study if you have recently participated in another research study involving experimental drugs or vaccines within the last 30 days or during this study. However, there is an exception if you participated in a study called B7841005.

I am on regular treatment with drugs that affect my immune system.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive prophylaxis treatment with marstacimab via subcutaneous injection

Up to 7 years

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

Open-label extension

Long-term safety, tolerability, and efficacy of marstacimab prophylaxis are assessed

Long-term

What Are the Treatments Tested in This Trial?

Interventions

• Marstacimab

Trial Overview

The trial tests marstacimab (PF-06741086), given as a weekly subcutaneous injection to prevent bleeding in hemophilia patients. Participants from an earlier phase will continue treatment to assess long-term safety and effectiveness. An optional substudy uses a pre-filled pen for administration.

How Is the Trial Designed?

Group I: PF-06741086 Experimental Treatment 1 Intervention

For participants aged ≥12 years 300 milligrams(mg) subcutaneous (sc) loading dose followed by 150 mg sq once weekly (qw). 300 mg sc qw is prescribed for participants who meet dose escalation criteria. For participants aged ≥6 to \<12 years is marstacimab 150 mg SC for initial loading dose followed by 75 mg SC QW. 150 mg sc qw is prescribed for participants who meet dose escalation criteria.

Marstacimab is already approved in United States, European Union for the following indications:

Approved in United States as Hympavzi for:

• Hemophilia A
• Hemophilia B

Approved in European Union as Hympavzi for:

• Hemophilia A
• Hemophilia B

Who Is Running the Clinical Trial?

Pfizer

Lead Sponsor

Trials

4,712

Recruited

50,980,000+

Known For

Vaccine Innovations

Top Products

Viagra, Zoloft, Lipitor, Prevnar 13

Albert Bourla

Pfizer

Chief Executive Officer since 2019

PhD in Biotechnology of Reproduction, Aristotle University of Thessaloniki

Patrizia Cavazzoni

Pfizer

Chief Medical Officer

MD from McGill University

Published Research Related to This Trial

In a three-month study involving 26 participants with hemophilia A or B, marstacimab, a monoclonal antibody targeting tissue factor pathway inhibitor (TFPI), was found to be safe and well tolerated, with 80.8% of participants experiencing treatment-emergent adverse events (TEAEs).

Marstacimab significantly reduced annualized bleeding rates (ABRs) compared to both an external control group and pretreatment rates, demonstrating its efficacy in managing bleeding episodes in hemophilia patients.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A phase 1b/2 clinical study of marstacimab, targeting human tissue factor pathway inhibitor, in haemophilia. Mahlangu, JN., Lamas, JL., Morales, JC., et al.[2023]

Marstacimab, a monoclonal antibody, was found to be safe and effective in preventing bleeding episodes in patients with severe hemophilia A and B during a long-term study of up to 365 days involving 20 participants.

The treatment was well tolerated, with no serious adverse events or thrombotic events reported, and it maintained a low annualized bleeding rate, demonstrating comparable efficacy to previous studies.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Long-term safety and efficacy of the anti-tissue factor pathway inhibitor marstacimab in participants with severe haemophilia: Phase II study results. Mahlangu, J., Luis Lamas, J., Cristobal Morales, J., et al.[2023]

In a study involving 18 patients with rare bleeding disorders, Marstacimab showed potential to improve thrombin generation in plasma samples, indicating it may help restore blood clotting balance.

While Marstacimab improved key thrombin generation metrics (lag time, peak, and ETP), none of the values reached normal levels, suggesting further research is needed to assess its clinical effectiveness in treating these disorders.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Anti-TFPI for hemostasis induction in patients with rare bleeding disorders, an ex vivo thrombin generation (TG) guided pilot study. Barg, AA., Brutman-Barazani, T., Avishai, E., et al.[2022]

Marstacimab, a monoclonal antibody, effectively enhances hemostasis in hemophilia A and B by increasing thrombin generation without causing excessive levels, making it a promising prophylactic treatment.

In a mouse model, marstacimab combined with activated prothrombin complex concentrate (aPCC) significantly reduced bleeding by 83.3%, indicating its potential effectiveness in preventing bleeding episodes in hemophilia patients.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Hemostatic efficacy of marstacimab alone or in combination with bypassing agents in hemophilia plasmas and a mouse bleeding model. Pittman, DD., Rakhe, S., Bowley, SR., et al.[2023]

Marstacimab is a promising investigational treatment for severe hemophilia A or B that works by neutralizing tissue factor pathway inhibitor (TFPI), potentially increasing the effectiveness of the coagulation pathway to prevent bleeding episodes.

Three validated electrochemiluminescence-based methods have been developed to detect antidrug antibodies (ADAs) against marstacimab, which is crucial for assessing the safety and efficacy of the treatment in clinical trials.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Evolution of Antidrug Antibody Assays During the Development of Anti-Tissue Factor Pathway Inhibitor Monoclonal Antibody Marstacimab. Donley, J., Jani, D., Zhu, T., et al.[2023]

Citations

1.

pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC12205756/

Marstacimab for the Treatment of Hemophilia A or B - PMC

Although marstacimab appears to have a favorable safety and efficacy profile, the potential for immunogenicity remains a critical consideration, ...

2.

pfizer.com

pfizer.com/news/press-release/press-release-detail/pfizer-announces-positive-topline-phase-3-results

Pfizer Announces Positive Topline Phase 3 Results for ...

Study demonstrates superiority, showing both statistically significant and clinically meaningful reduction in annualized bleeding rate with ...

3.

ashpublications.org

ashpublications.org/blood/article/146/14/1654/546041/Marstacimab-prophylaxis-in-hemophilia-A-B-without

Marstacimab prophylaxis in hemophilia A/B without inhibitors

Key PointsMarstacimab, a monoclonal antibody, targets the tissue factor pathway inhibitor to rebalance hemostasis.Marstacimab reduced bleeding events and w.

4.

clinicaltrials.gov

clinicaltrials.gov/study/NCT03938792

NCT03938792 | Study of the Efficacy and Safety PF ...

Marstacimab prophylaxis in hemophilia A/B without inhibitors: results from the phase 3 BASIS trial. Blood. 2025 Oct 2;146(14):1654-1663. doi: 10.1182/blood ...

5.

hematologyadvisor.com

hematologyadvisor.com/news/hemophilia-marstacimab-efficacy-inhibitors-treatment-risk/

Marstacimab Shows Efficacy in Hemophilia With Inhibitors

Once-weekly subcutaneous marstacimab (Hympavzi™) significantly reduced bleeding episodes in patients with hemophilia A or B with inhibitors, ...

6.

bleeding.org

bleeding.org/news/pfizer-announces-phase-3-trial-results-for-hemophiliainhibitor-therapy

Pfizer Announces Phase 3 Trial Results for Hemophilia ...

HYMPAVZI™ (marstacimab-hncq) is FDA-approved for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adults and ...

7.

pubmed.ncbi.nlm.nih.gov

pubmed.ncbi.nlm.nih.gov/40608864/

Marstacimab prophylaxis in hemophilia A/B without inhibitors

Previous phase 1 and 2 trials established marstacimab safety and efficacy in adults with severe hemophilia A (HA) or B (HB). BASIS is an open- ...