Sangamo Therapeutics, Inc. (NASDAQ: SGMO) today presented interim data from the Phase 1/2 EMPOWERS Study evaluating the SB-318 zinc finger nuclease (ZFN) in vivo (inside the body) genome editing product candidate in patients with Mucopolysaccharidosis Type I (MPS I). These data, along with interim results of the CHAMPIONS Study evaluating SB-913 for MPS II, were presented today at the WORLDSymposium 2019 being held in Orlando, Florida. Sangamo believes data from these two studies provide complementary evidence supportive of a favorable safety profile and of the activity of the ZFN in vivo genome editing technology used in both SB-318 and SB-913. The two WORLDSymposium presentations have been made available on the Sangamo website.
“The results so far suggest a dose-dependent increase in leukocyte IDUA enzyme activity,” said Dr. Paul Harmatz, a professor at UCSF Benioff Children’s Hospital Oakland and a lead investigator on the study. “Leukocytes are an easily accessible target tissue for IDUA and therefore provide an estimate of tissue enzyme activity for patients with MPS I. Whether these observed increases will translate into clinical benefit from SB-318 is yet to be determined.”
MPS I, also known as Hurler syndrome, is a rare genetic disorder caused by a deficiency of alpha-L-iduronidase (IDUA), a lysosomal enzyme which is required to break down or recycle the toxic buildup of glycosaminoglycans (GAGs). Without IDUA enzyme activity, GAGs accumulate in cells throughout the body, leading to widespread tissue and organ damage. The current standard-of-care treatment for MPS I is enzyme replacement therapy (ERT), given as weekly intravenous infusions. For severe MPS I patients, bone marrow transplant is also a common treatment. SB-318 is an investigational product candidate being evaluated to treat MPS I using ZFNs, which are designed to insert a normal copy of the IDUA gene into a precise location in the DNA of liver cells. The goal of SB-318 treatment is to enable a patient’s liver to produce a continuous supply of functional IDUA enzyme.
“It is a tremendous responsibility to undertake the first in vivo genome editing clinical trials, and we are learning quickly about our technology and about these rare diseases,” said Dr. Edward Conner, Chief Medical Officer of Sangamo. “While additional data will be critical in assessing the safety profile and potential therapeutic benefit of SB-318, these early data provide evidence of the progress that we are making toward a potential new treatment for MPS I using in vivo genome editing with ZFNs.”