Sangamo Shares Sink After Data Release For Gene Editing Product Candidate

Sangamo Therapeutics Inc SGMO shares opened sharply lower Wednesday following the release of clinical trial data for its pipeline candidate SB-913.

SB-913 is a zinc finger nuclease in vivo genome editing product candidate being tested for mucopolysaccharidosis type II, or Hunter syndrome.

MPS II is caused by the deficiency of the iduronate-2-sulfatase — or IDS — enzyme, which is needed to break down or recycle glycosaminoglycans, or GAGs, dermatan sulfate and heparan sulfate.

The stock was down 16.54 percent to $15.90 after the open Wednesday. 

What Happened

Sangamo said the CHAMPIONS study, which evaluated three separate doses of SB-913 over a 36-month period, showed that it was generally well-tolerated, with no serious adverse events.

The data was from two cohorts with two subjects each, which were administered low- and mid-doses, respectively, while enrollment for cohort 3 was completed recently.

Total CAGs, dermatan sulfate and heparan sulfate were below baseline throughout 16 weeks for the cohort 2 subjects, with mean reductions of 51 percent, 32 percent and 61 percent, respectively. Plasma IDS activity at baseline and for the first 16 weeks was below the level of quantification of the current assay, the company said.

The company presented at the 2018 Annual Symposium of the Society for the Study of Inborn Errors of Metabolism in Athens, Greece.

Why It's Important

If Sangamo is able to deliver positive results for longer-term studies, genome editing has the potential to achieve a breakthrough in monogenic diseases such as MPS II.

What's Next

Sangamo said the safety monitoring committee of the study will review data from all the three cohorts later this year. The company said it would present the longer-term safety and efficacy data from the CHAMPIONS study at the 2019 WORLD Symposium meeting in Orlando, Florida, in February. 

It remains to be seen if the changes achieved are sustainable after the withdrawal of the enzyme replacement therapy.

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