FDA Clears Hemophilia A Gene Therapy, SB-525, for Testing in Patients

A Sangamo Therapeutics‘ gene therapy program to potentially treat hemophilia A, called SB-525, has been cleared by the U.S. Food and Drug Administration (FDA) for clinical testing in adult patients.

The company announced that the FDA approved its Investigational New Drug (IND) application for SB-525, a necessary first step in conducting clinical trials.

The move will allow Sangamo to evaluate SB-525’s safety, tolerability, and effectiveness.

Hemophilia A is caused by a defect in the gene encoding factor VIII protein, which is involved in the clotting process. People who carry the gene mutation may experience bleeding spontaneously or after suffering an injury.

The SB-525 gene therapy program uses an adeno-associated virus (AAV2/6) cDNA human factor VIII construct. In preclinical studies, it appeared significantly more potent than other AAV-based cDNA constructs being evaluated to treat hemophilia A. The treatment could allow clinically relevant levels of the factor VIII protein to be reached using lower doses.

“We are very pleased to begin 2017 with the announcement of an open IND for our SB-525 cDNA gene therapy and intend to initiate a clinical trial evaluating SB-525 as soon as possible,” Sandy Macrae, MB, ChB, PhD, chief executive officer of Sangamo, said in a press release. “We are committed to developing the best therapeutic options for patients, and based on non-human primate studies, SB-525 has demonstrated the potential to be the best-in-class treatment for Hemophilia A.”

SB-525 is one of four programs in Sangamo’s clinical portfolio of in vivo genomic therapies for rare diseases. The company plans to conduct clinical trials this year for the other three:

• SB-FIX, an in vivo genome editing therapy for hemophilia B will be evaluated in a Phase 1/2 clinical trial
• In vivo genome editing therapies for lysosomal storage disorders — Mucopolysaccharidosis (MPS) type I (SB-318) and MPS type II (SB-913) — will be evaluated in two Phase 1/2 clinical trials. MPS interferes with the body’s ability to break down and recycle specific mucopolysaccharides, which are long chains of sugar molecule used to build connective tissues.

Standard treatment for hemophilia currently involves replacing the defective clotting factor through regular, often frequent, infusions of recombinant clotting factors or plasma concentrates. In more severe cases, people with hemophilia A require ongoing, preventive infusions.