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

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.