Gene therapy offers hope for hemophilia b patients

NCT ID NCT03307980

Completed Disease control Sponsor: Pfizer Source: ClinicalTrials.gov ↗

First seen Jun 25, 2026 · Last updated Aug 12, 2026 · Updated 3 times

Summary

This study tests a gene therapy (PF-06838435) for people with severe hemophilia B, a bleeding disorder. The therapy uses a harmless virus to deliver a working gene for clotting factor IX. Researchers are following 21 participants long-term to see if it is safe and reduces bleeding. Some participants receive a higher dose in a substudy.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: PF-06838435 (a gene therapy using a modified virus to deliver a working factor IX gene)
What this could lead to: If successful, this gene therapy could allow people with hemophilia B to produce their own clotting factor, reducing or eliminating the need for regular infusions.
What could go wrong: This is a small, early-phase study (21 participants) focused on safety. Gene therapy carries risks like immune reactions or the treatment not lasting long-term. It may not work for everyone.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

hemophilia A hemophilia B

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

HEMOPHILIA B

Contacts and locations

Locations

Ege Universitesi Tip Fakultesi Cocuk Sagligi ve Hastaliklari Anabilim Dali

Izmir, 35100, Turkey (Türkiye)
Istanbul Universitesi Onkoloji Enstitusu Çocuk Hematoloji Onkoloji Bilim Dali

Istanbul, 34093, Turkey (Türkiye)
Istanbul University Clinical Trials Excellence Center

Istanbul, 34452, Turkey (Türkiye)
LA Center for Bleeding and Clotting Disorders

New Orleans, Louisiana, 70112, United States
LA Center for Bleeding and Clotting Disorders - Metairie

Metairie, Louisiana, 70001, United States
Louisiana Center for Advanced Medicine

Slidell, Louisiana, 70461, United States
McGill University Health Center - Research Institute

Montreal, Quebec, H4A 3J1, Canada
McMaster University

Hamilton, Ontario, L8S 3L8, Canada
McMaster University Medical Centre - Hamilton Health Sciences

Hamilton, Ontario, L8N 3Z5, Canada
Mississippi Center for Advanced Medicine

Madison, Mississippi, 39110, United States
Royal Prince Alfred Hospital

Camperdown, New South Wales, 2050, Australia
The Children's Hospital of Philadelphia

Philadelphia, Pennsylvania, 19104, United States
The Research Institute of the McGill University Health Centre

Montreal, Quebec, H3H 2R9, Canada
Tulane Lakeside Hospital

Metairie, Louisiana, 70001, United States
Tulane University Clinical Translational Unit

New Orleans, Louisiana, 70112, United States
Tulane University Hospitals and Clinic

New Orleans, Louisiana, 70112, United States
Tulane University School of Medicine

New Orleans, Louisiana, 70112, United States
UC Davis Comprehensive Cancer Center

Sacramento, California, 95817, United States
UC Davis Ellison Ambulatory Care Clinic

Sacramento, California, 95817, United States
UC Davis Medical Center

Sacramento, California, 95817, United States
UC Davis Medical Center department of Radiology

Sacramento, California, 95817, United States
UC Davis Midtown Cancer Center

Sacramento, California, 95817, United States
UC DavisHealth Main Hospital

Sacramento, California, 95817, United States
University Medical Center New Orleans

New Orleans, Louisiana, 70112, United States
Weill Cornell Medicine - New York Presbyterian Hospital

New York, New York, 10065, United States

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