What is hemophilia A?

Hemophilia A patients have an inherited gene mutation that impairs their ability to produce normal levels of a blood clotting factor called factor VIII. This results in disabling or life-threatening bleeding, arising spontaneously or caused by trauma. Routine activities have the potential to cause prolonged bleeding, either externally or internally. Frequent sites of internal bleeding include the joints and muscles. 

The current standard of care involves frequent intravenous infusions of the factor VIII protein or a subcutaneously delivered non-factor-based therapy called emicizumab.

Read more about the causes, symptoms, and diagnosis of hemophilia.

How is gene therapy used to treat hemophilia A?  

Gene therapy for hemophilia A is in clinical testing, with the goal of improving the blood’s ability to clot, ideally over decades or for the rest of a patient’s lifetime. Gene therapy for hemophilia A is a one-time infusion that uses a vector to deliver a functional gene to replace the hemophilia patient’s own defective gene or a therapeutic gene to provide a missing protein. The result is better clotting factor activity, which protects against bleeding.

Recently, a clinical trial in which Lindsey George, MD, was the lead clinical investigator demonstrated stable and durable factor VIII expression following gene therapy in hemophilia A patient participants. Most of the participants sustained the improved clotting factor activity after two years.

Hemophilia A treatment options at CHOP 

At CHOP, the Novel Therapeutics for Bleeding Disorders (NoT Bleeding) Program, led by Dr. George, offers state-of-the-art clinical care, including experimental gene therapy and novel hemophilia therapeutics, as well as a basic and translational research program. 

FDA-approved gene therapies

There are currently no FDA-approved gene therapies for hemophilia A. Researchers at Children’s Hospital of Philadelphia are working to change that.

Clinical trials for hemophilia A

CHOP is one of the world’s foremost sites for pediatric research studies and clinical trials.

There are currently active gene therapy clinical trials for hemophilia A:  

• Check back for an up-to-date list of trials