Sangamo BioSciences has received orphan drug designation from the US Food and Drug Administration (FDA) for SB-FIX, the company’s investigational “genome editing” therapy to treat hemophilia B. The designation allows for accelerated approval, so that much-needed drugs or biologics become available to patients with rare, life-threatening diseases who need effective treatments.
Sangamo is currently employing its proprietary genome editing to create therapies for both hemophilia A and B. The new treatments are developed using adeno-associated viruses (AAVs) as delivery vehicles, or vectors, to carry the genetic codes that initiate the production of the deficient factor protein—in this case factor IX (FIX) in those with hemophilia B. The AAVs deliver this genetic material into liver cells, without causing disease or triggering significant immune responses.
The AAVs are further customized to include zinc finger nuclease (ZFN)-mediated genome editing. ZFNs are a class of engineered DNA-binding proteins that act as scissors to “cut” a functional FIX gene and insert it into a specific location in liver cells, where a steady production of therapeutic levels of FIX occurs. According to a Sangamo press release, the capacity to permanently integrate the therapeutic gene in a highly specific and targeted fashion is what distinguishes Sangamo’s in vivo genome editing approach from conventional AAV gene therapy techniques, which are nonintegrating and may “wash out” of the liver as cells divide and turn over.
“By enabling targeted integration of a therapeutic factor IX gene, our ZFN-mediated genome editing approach may offer hemophilia B patients a therapeutic option that has potential advantages over conventional gene therapy approaches,” said Geoff Nichol, MB, ChB, Sangamo’s executive vice president of research and development. “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.”
The company expects to initiate a Phase 1/2 clinical study of the therapy in adult hemophilia B patients in the latter part of 2016.
Source: Sangamo press release dated September 6, 2016
