Sangamo Therapeutics announced that the FDA has granted Fast Track designation to SB-318 and SB-913, the company's clinical stage in vivo genome editing product candidates for the treatment of Mucopolysaccharidosis Type I (MPS I) and MPS II, respectively. The FDA's Fast Track designation is designed to facilitate the development and expedite the review of drugs and biologics to treat serious conditions and fill an unmet medical need. Once a drug receives Fast Track designation, early and frequent communication with the FDA is encouraged throughout the development and review process. The frequency of communication is designed to ensure that questions and issues are resolved quickly, potentially leading to earlier drug approval and access by patients.

MPS I and MPS II are caused by mutations in the genes encoding alpha-L-iduronidase (IDUA) and iduronate 2-sulfatase (IDS) enzymes, respectively. Using Sangamo's zinc finger nuclease (ZFN) genome editing technology, SB-318 (for MPS I) and SB-913 (for MPS II) are designed as a single treatment strategy intended to provide stable, continuous production of the IDUA or IDS enzyme for the lifetime of the patient.

SB-318 and SB-913 have already received Orphan Drug and Rare Pediatric Disease designations from the FDA. The FDA has cleared an Investigational New Drug application for these programs, and Phase 1/2 clinical trials evaluating SB-318 and SB-913 in adults with MPS I and MPS II, respectively, are open and screening subjects for enrollment.

Sangamo's ZFN-mediated in vivo genome editing approach makes use of the endogenous albumin gene locus, a highly expressing and liver-specific 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. The ability to permanently integrate the therapeutic gene in a highly specific, targeted fashion significantly differentiates Sangamo's in vivo genome editing approach from conventional AAV cDNA gene therapy. Ultimately, the target population for these programs will include pediatric patients, and it will be important in this population to be able to produce stable levels of therapeutic protein for the lifetime of the patient.