CHOP’s Hemostasis and Thrombosis Center Celebrates 50th Anniversary

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The Hemostasis and Thrombosis Center (HTC) at Children’s Hospital of Philadelphia (CHOP) is proudly celebrating 50 years of providing comprehensive care to children and adolescents with hemophilia and other inherited bleeding or clotting disorders. The Center was founded in 1973 and was one of the first HTCs established in the country and is considered a Center of Excellence for the diagnosis, treatment and prevention of bleeding and clotting disorders, serving as a national resource for other institutions.

“What started at CHOP as caring for 48 patients a year with hemophilia has grown into providing care for over 1,000 children with all types of bleeding and clotting disorders at our Center,” says Leslie Raffini, MD, Director of the Hemostasis and Thrombosis Center at Children’s Hospital of Philadelphia. “It’s been an incredible journey to witness the advancement of treatment options for our patients, which today includes an FDA-approved potentially curative gene therapy option for patients with hemophilia B.”

The Last 50 Years of Hemophilia Treatment

Hemophilia is an X-linked inherited bleeding disorder that is caused by a clotting factor deficiency that can cause frequent, painful joint bleeds and disability. There are two types of hemophilia. Factor VIII deficiency or hemophilia A, is the most common type of hemophilia, while factor IX deficiency, or hemophilia B, is about four times less common. In the 1970s, patients were taught to treat bleeding episodes at home with donated plasma-derived clotting factor concentrates. In the 1980s, during the AIDS epidemic in the U.S., the blood supply many of these patients received was contaminated with HIV from infected blood donors. During this time, donated blood was the only treatment available for hemophilia patients, which led to many of them becoming infected with HIV.

In the 1990s, genetically engineered recombinant clotting factors became available, making it safer and easier for patients to administer the treatments at home. By the mid 1990s most of CHOP’s patients with hemophilia were receiving 2-3 infusions of clotting factor per week at home to prevent joint bleeds. Although this worked well to prevent joint damage, caregivers had to infuse the clotting factor into their child’s veins, which was painful and stressful.

In 2017, a new treatment called emicizumab was approved to prevent joint bleeds in hemophilia A.  This treatment is given as a small subcutaneous injection every 1-4 weeks and provides excellent protection from bleeding.

“Most patients with hemophilia A at CHOP are treated with this product and do well without any joint bleeds or damage,” said Raffini. “Most children lead a very active and normal lifestyles, with the exception of participating in high-contact sports like football or hockey.”

On the Cusp of Additional New Gene Therapies

In 2022, the FDA approved the first gene therapy product for hemophilia B patients 18 years of age or older. Gene therapy has the potential to cure genetic disorders such as hemophilia. There are currently numerous other gene therapy products in development for hemophilia that are expected to be available to patients in the coming decade.

CHOP has led the development of hemophilia gene therapy through basic, translational and clinical research efforts and recently launched the Novel Therapeutics for Bleeding Disorders (NoT Bleeding) Program, which is housed in CHOP’s HTC. The team is led by world-class experts who together have more than two decades of clinical experience in gene therapy for hemophilia and in innovating care for patients with bleeding disorders. 

A Unique Perspective

htc team Regina Butler, RN-BC, clinical manager for the Division of Hematology at CHOP has been with the institution since the HTC’s inception and has spent the last 50 years as a hemophilia nurse and an international leader in the field.

“It has been an amazing experience to observe the tremendous advances in this field since I started in the 1970s,” said Butler. “Hemophilia has changed from a disease that caused disability and pain that severely impacted the lives of patients and their families to a disorder with minimal complications and that is much more manageable. Seeing our patients lead healthy and active lives today is tremendously rewarding.”

The HTC at CHOP is comprised of a multi-disciplinary team made up of clinicians, nurses, social workers, physical therapists, and researchers. CHOP is part of the national network of federally funded HTCs in the U.S. and previously served as the Core Center for the 16 HTCs in the Mid-Atlantic Region for 15 years under the leadership of Regina Butler. As a Core Center, CHOP oversaw the services provided by the Mid-Atlantic Region III HTCs and collaborated with the Maternal and Child Health Bureau and CDC to improve treatment and support for people with hemophilia and other inherited bleeding and clotting disorders. For more information about CHOP’s HTC, visit here

Contact: Jennifer Lee, The Children’s Hospital of Philadelphia, 267-426-6084 or