Last month, biotechnology company BioMarin sought approval for an investigational gene therapy (valoctocogene roxaparvovec) for patients with hemophilia A. However, their approval was denied. Instead, the company was told that approval hinged upon clinical trial data on safety, efficacy, and tolerability. According to the National Hemophilia Foundation, BioMarin is completing additional trials beyond the norm. In fact, their SAVVY study seeks to understand the relationship between antibodies and gene therapy.
Gene Therapy: The Basics
In many cases, gene therapy depends upon an adeno-associated virus (AAV) for delivery. An article in BioDrugs describes AAVs as:
a non-enveloped virus that can be engineered to deliver DNA to target cells. The ability to generate recombinant AAV particles lacking any viral genes and containing DNA sequences of interest for various therapeutic applications has thus far proven to be one of the safest strategies for gene therapies.
In this situation, valoctocogene roxaparvovec delivers functional genes to promote FVIII production. However, researchers believe that SAVVY will help them understand the sustained effects of this therapy. Will patients develop antibodies and quickly remove the therapy from the body? How often will AAV5, AAV6, and AAV8 be found in blood?
Through this research, BioMarin will be able to determine the efficacy of AAVs, determine new methods for testing and analyzing antibodies, and explore how (and why) antibodies might change over a specified period of time.
Also known as Factor VIII (FVIII) deficiency, hemophilia A is a genetic bleeding disorder. Patients with hemophilia A are missing, or have defective, FVIII, a clotting protein. Generally, this condition affects mostly males. However, it can affect females in rare cases. An estimated 20,000 U.S. citizens have hemophilia A. Symptoms include:
- Easy and frequent bruising and bleeding
- Urinary and digestive tract bleeding
- Excessive menstruation or heavy bleeding following childbirth
- Prolonged nosebleeds
- Joint pain and swelling
Learn more about hemophilia A.