AveXis’s gene therapy is meant to be a one-time treatment, infused into a vein during a 60-minute procedure. It uses an engineered virus to deliver healthy copies of the SMN1 gene to cells throughout the body. Once there, the new gene starts making a protein that’s essential for the survival of motor neurons.
If you wait, however, “the children have limited motor neurons for the gene therapy to get into and work effectively,” says Sukumar Nagendran, AveXis’s chief medical officer.
On average, the 15 children in the AveXis trial received the gene therapy four months after birth. They all responded, but Nagendran says two children who got it within the first two months of life had the most dramatic improvement; they’re now able to walk independently.
In April, AveXis began a new study, this time treating babies immediately after birth. The results will be able to tell researchers just how much better patients fare when they get the drug as newborns.
Other gene therapies may also work better in children before a genetic defect has time to irreparably damage the body. For example, Bluebird Bio is developing one that halted a deadly brain disorder called cerebral adrenoleukodystrophy (ALD), also known as Lorenzo’s Oil disease, in 15 out of 17 children. In a statement provided to MIT Technology Review, the company said outcomes are better when patients are treated before symptoms appear.
On February 8, a national committee that oversees newborn testing voted to recommend that SMA be added to the recommended universal screening panel. The next step is for the secretary of the US Department of Health and Human Services, Alex Azar, to sign off.
Even then, rolling out SMA screening for every newborn isn’t a done deal. A recommendation put forth by the committee is just that—a recommendation. It’s only binding in two states, California and Florida. Other states may choose to adopt the proposal or not.