FDA Grants Fast Track Designation to Gene Therapy for Hemophilia A Patients

Mathew Shanley

Earlier today, Sangamo Therapeutics, Inc. announced that the U.S. Food and Drug Administration (FDA) granted Fast Track designation to the company’s clinical stage gene therapy candidate for hemophilia A patients – SB-525.

Hemophilia A is the effect of mutations in the F8 gene, and is a monogenic, rare bleeding disorder in which the blood does not clot normally. Per the Centers for Disease Control and Prevention, hemophilia affects an estimated 1 in every 5,000 male births, with an estimated 20,000 males in the U.S. living with the disorder.

With a single infusion, the treatment uses a recombinant adeno-associated virus (rAAV) to deliver a human Factor VIII cDNA construct and proprietary, synthetic liver-specific promoter to the nucleus of liver cells. The therapy is proposed to deliver continuous, therapeutic expression of Factor VIII protein.

The FDA’s Fast Track designation will facilitate the development and expedite the review of the drug.

The mutations in the F8 gene that cause hemophilia A encode Factor VIII clotting protein that assists in blood clotting and stops bleeding if blood vessels are injured. It is likely that persons with the mutation will experience bleeding episodes after injury, and spontaneous bleeding episodes that can lead to further joint disease and disorders like arthritis.

Continuous, therapeutic expression of Factor VIII protein will be provided through the single-treatment strategy, and the FDA has already granted SB-525 Orphan Drug designation and cleared an Investigational New Drug application for the program.

SB-525 is being developed as part of an exclusive, global team-up and license arrangement with Pfizer Inc., and a Phase 1/2 clinical trial assessing the treatment in adults with hemophilia A is projected for the second quarter of 2017, and data from the study are likely by late 2017 or early 2018.
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