Companies that develop medications using the revolutionary gene-editing technology CRISPR took a hit on Monday after a study found some concerns about an immune response to the technology.

CRISPR Therapeutics dropped sharply on Monday before rebounding, ending the day down 2.8%. Intellia Therapeutics and Editas Medicine both fell by about 11%.

Executives at CRISPR Therapeutics told Business Insider that the concern of an immune response wasn't a surprise, and they don't see it being a big problem.



A revolutionary gene-editing technology is making its way into humans for the first time in 2018.

CRISPR-Cas9 is a gene-editing tool that allows researchers to go into a cell, find a particular gene, and make a change to it. Cas9, the protein that does the cutting, is found in Streptoccus and Staphylococcus bacteria, both of which humans are exposed to throughout their life.

That has people worried about what that will mean for how well CRISPR-Cas9 works in humans. A paper published Friday detailed concerns about a potential immune response, in the way that the body might respond to a bacterial infection. That could render the therapy ineffective if the body went after the protein before it was able to make its edit.

Publicly traded CRISPR-based companies dropped sharply on the study. CRISPR Therapeutics fell more than 10% before rebounding on Monday, ending the day down almost 3% Intellia Therapeutics and Editas Medicine both fell by about 11%.

But the immune response possibility wasn't news to CRISPR Therapeutics, which plans to launch human trials for its therapy to treat the blood disorder beta-thalassemia in Europe in 2018.

CRISPR Therapeutics chief scientific officer Dr. Bill Lundberg told Business Insider that the hope is that the Cas9 protein that does the editing and is associated with immune responses isn't around for very long. For example, if the treatment is applied to cells outside the body, with the edited cells getting put back into the body to treat a particular patient, by that point, most of the Cas9 protein would be gone.

"The scissors need to be there long enough to make a snip, but then they can go away," Lundberg said.

What will remain is a change to the genes that ideally persists even after the scissors make an exit that continues to treat the disease by correcting what was faulty.

"The genetic change you make is going to be in your body forever and ever, but the CRISPR will go away," CRISPR Therapeutics CEO Samarth Kulkarni told Business Insider. "You don't want to have molecular scissors hanging out in your body."