Death in CRISPR gene therapy study sparks search for answers

The lone volunteer in a unique study involving a gene-editing technique has died, and those behind the trial are now trying to figure out what killed him.

Terry Horgan, a 27-year-old who had Duchenne muscular dystrophy, died last month, according to Cure Rare Disease, a Connecticut-based nonprofit founded by his brother, Rich, to try and save him from the fatal condition.

Although little is known about how he died, his death occurred during one of the first studies to test a gene editing treatment built for one person. It's raising questions about the overall prospect of such therapies, which have buoyed hopes among many families facing rare and devastating diseases.

“This whole notion that we can do designer genetic therapies is, I would say, uncertain,” said Arthur Caplan, a medical ethicist at New York University who is not involved in the study. “We are out on the far edge of experimentation."

The early-stage safety study was sponsored by the nonprofit, led by Dr. Brenda Wong at the University of Massachusetts Chan Medical School and approved by the Food and Drug Administration. The hope was to use a gene-editing tool called CRISPR to treat Horgan's particular form of Duchenne muscular dystrophy. The rare, genetic muscle-wasting disease is caused by a mutation in the gene needed to produce a protein called dystrophin. Most people with Duchenne die from lung or heart issues caused by it.

At this point, it's unclear whether Horgan received the treatment and whether CRISPR, other aspects of the study or the disease itself contributed to his death. Deaths are not unheard of in clinical trials, which test experimental treatments and sometimes involve very sick people.

But trials involving CRISPR are relatively new. And Fyodor Urnov, a CRISPR expert at the Innovative...