Sangamo Sinks Most in a Decade as Gene-Editing Study Fizzles

(Bloomberg) -- Sangamo Therapeutics Inc. tumbled 48 percent, the most in a decade, after a pair of early-stage studies failed to demonstrate the benefit of two gene-editing medicines. Peers that employ CRISPR gene-editing technology also sank to session lows.

Interim results from Sangamo’s “Champions” study suggest that gene-edited liver cells can generate a missing enzyme in patients with the disease known as MPS II, but they don’t appear to be producing enough to be beneficial. Analysts had said the drugmaker needed to show production of the so-called IDS enzyme to regain investor confidence after delays for other medicines in its portfolio. The stock had already fallen 39 percent in the prior year.

Sangamo Sinks Most in a Decade as Gene-Editing Study Fizzles
  • Other gene-editing stocks sank on the news -- Editas sank as much as 10 percent, Crispr Therapeutics fell as much as 9.9 percent, and Intellia dropped as much as 8.4 percent
  • “You can see a small increase in the enzyme but we don’t think that would be enough to make a difference,” Chief Executive Officer Sandy Macrae said by phone; the company is “very encouraged” by the large effects seen in one of the patients
  • Liver tissue analysis found successful genome editing using a test developed by Sangamo, although a less sensitive test did not detect editing in low- and mid-dose patients
  • Glycosaminoglycan (GAG) measurements for patients at 24 weeks did not show a substantial increase or decrease in relation to the dose
    • Analysts were looking for a sustained reduction in GAGs, as they can lead to tissue and organ damage
    • Some patients have started withdrawal from enzyme replacement therapy, but one patient was recommended to resume ERT due to fatigue and increasing GAGs
  • There were 3 serious adverse events, although none were deemed related to the drug
  • A separate study of SB-318 in MPS I showed a dose-dependent increase in leukocyte IDUA enzyme activity in patients who received a higher dose of the drug, although the potential benefit is “yet to be determined”
    • GAG measurements for the three patients were at or slightly above normal
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