Sangamo’s Genome Editing Therapy for Hemophilia B Named ‘Orphan Drug’ by FDA

Sangamo BioSciences announced that its zinc finger nuclease (ZFN)-mediated genome editing product, SB-FIX, has received orphan drug designation from the U.S. Food and Drug Administration (FDA), speeding its development as a potential treatment for hemophilia B.

Sangamo plans to initiate a Phase 1/2 clinical trial, SB-FIX-1501, in adults with this disease later this year.

“We are pleased with the FDA’s decision to grant orphan drug designation to SB-FIX for hemophilia B,” Geoff Nichol, MD, ChB, Sangamo’s executive vice president of research and development, said in a press release. “By enabling targeted integration of a therapeutic factor 9 gene, our ZFN-mediated genome editing approach may offer hemophilia B patients a therapeutic option that has potential advantages over conventional gene therapy approaches.

“We will enroll adult hemophilia patients into our first clinical trial, however, our goal is to move into pediatric patients, a population we believe could particularly benefit from a treatment that has the potential to provide lifelong expression of therapeutic levels of Factor IX protein,” Nichol added.

Hemophilia B is a rare bleeding disorder occurring in about one in every 50,000 male births, with approximately 4,000 males currently affected in the United States, according to the National Hemophilia Foundation.

In hemophilia, the blood does not clot normally due to mutations in genes that encode factors that help to stop bleeding when blood vessels are injured. Hemophilia B is caused by a defect in the gene encoding clotting Factor IX (FIX) protein.

SB-FIX is designed to be a one-time treatment, capable of providing stable, continuous production of Factor IX proteins throughout a  patient’s life. The ZFN-mediated in vivo genome editing approach developed by Sangamo uses the albumin gene locus – a genomic ‘safe-harbor site’ that is highly expressing and liver-specific – to edit ZFNs so that they can accept and express certain therapeutic genes.

“Our mission is to translate our ground-breaking science into genetic therapies that transform patients’ lives,” said Sandy Macrae, MB, ChB, PhD, president and chief executive officer of Sangamo. “This is another positive step forward for the first therapeutic in vivo genome editing application cleared for clinical evaluation in humans. I am pleased with the progress that we have made to advance this program and we look forward to initiating a Phase 1/2 clinical trial by the end of 2016.”

The study (NCT02695160), expected to be conducted at five sites in the U.S., is registered on the clinical trials.gov website, but is not yet recruiting patients.