Gene therapy extending lives of sick babies

Study shows promise in treating muscle disease

WASHINGTON — A first attempt at gene therapy for a disease that leaves babies unable to move, swallow and, eventually, breathe has extended the tots’ lives, and some began to roll over, sit and stand on their own, researchers reported Wednesday.

Only 15 babies with spinal muscular atrophy received the experimental gene therapy, but researchers in Ohio credited the preliminary and promising results to replacing the infants’ defective gene in the first few months of life, before the neuromuscular disease destroyed too many key nerve cells.

“They all should have died by now,” said Dr. Jerry Mendell of Nationwide Children’s Hospital, who led the work published by The New England Journal of Medicine.

Mendell cautioned that much more study is needed to prove the gene therapy works and is safe.

Scientists loaded a healthy version of the gene into a virus modified so it couldn’t cause illness. Then 15 babies got a one-time intravenous injection. The virus carried the healthy gene into motor neurons, where it got to work producing the protein those nerve cells require to live.

Three babies received a low dose of the gene therapy, as a first-step safety precaution. The remaining 12 got a high dose.

All of the children are alive, Mendell said, about two years and counting after treatment. All beat the odds of needing permanent machine help to breathe by 20 months.

But only the high-dose recipients saw better motor control. Eleven could sit unassisted at least briefly; nine could roll over. Eleven are speaking and able to swallow. Two were able to crawl, stand and then walk, Mendell’s team reported.

The only serious side effect attributed to the gene therapy so far involved possible signs of a liver problem that eased with treatment.