Image by Spencer Phillips
DNA helix
The US Food and Drug Administration (FDA) has granted fast track designation to SB-FIX for the treatment of hemophilia B.
SB-FIX is a zinc finger nuclease (ZFN)-mediated genome-editing product candidate.
It is designed to be used as a one-time treatment that will provide stable, continuous production of factor IX (FIX) for the lifetime of the patient.
The ZFN-mediated in vivo genome-editing approach makes use of the albumin gene locus, a highly expressing and liver-specific genomic “safe-harbor site,” that can be edited with ZFNs to accept and express therapeutic genes.
The approach is designed to enable the patient’s liver to permanently produce circulating therapeutic levels of a corrective protein product.
This differs from conventional adeno-associated virus complementary DNA gene therapy approaches, which are non-integrating and may “wash out” of the liver as cells divide and turn over.
Sangamo Therapeutics, Inc., the company developing SB-FIX, has initiated a phase 1/2 trial of SB-FIX in adults with hemophilia B. The trial is open, and subjects are being screened for enrollment.
In addition to fast track designation, SB-FIX has orphan designation from the FDA (granted in 2016).
About fast track designation
The FDA’s fast track program is designed to facilitate the development and expedite the review of products intended to treat or prevent serious or life-threatening conditions and address unmet medical need.
Through the fast track program, a product may be eligible for priority review. In addition, the company developing the product may be allowed to submit sections of the new drug application or biologic license application on a rolling basis as data become available.
Fast track designation also provides the company with opportunities for more frequent meetings and written communications with the FDA.
About orphan designation
The FDA grants orphan designation to products intended to treat, diagnose, or prevent diseases/disorders that affect fewer than 200,000 people in the US.
The designation provides incentives for sponsors to develop products for rare diseases. This may include tax credits toward the cost of clinical trials, prescription drug user fee waivers, and 7 years of market exclusivity if the product is approved.
