Gene Therapy, Results

AveXis offers compelling reasons for a fast FDA OK for gene therapy to treat spinal muscular atrophy in infants

For most infants suffering from spinal muscular atrophy type 1, the chances are quite high that they could die or require constant respiratory assistance early on to allow them to keep breathing, with no motor function ability for simple things like sitting unassisted. Most die before the age of 4.

But in a small Phase I study of 15 patients treated with AveXis’ $AVXS gene therapy for SMA, all of the patients were able to reach 20 months without the need for constant respiratory support, or dying. And many achieved improvements in motor symptoms, speaking to the potential — though still unproven — of this as a once-and-done therapy for a rare but dire ailment.

The New England Journal of Medicine published those complete Phase I data points, out today, as the biotech pursues a pivotal study while exploring the possibility of an accelerated FDA approval that could — possibly — provide a shortcut to commercial work.

Sean Nolan

The news today is remarkable for several reasons. It puts AveXis in the front ranks of gene therapy companies as Spark appears poised to gain a pioneering US approval for its lead gene therapy for an eye disease. And it also poses a direct threat to Biogen’s new franchise for Spinraza, priced at $750,000 for the first year — one of the top 10 most expensive therapies in the world — and half that rate for each year after.

“We do have a meeting scheduled late in the fourth quarter to meet with the FDA,” says Chicago-based AveXis CEO Sean Nolan. “We’ve said we would do everything we could to move along the filing and hopefully the approval. We do see there are a couple of potential scenarios that could lead to a more accelerated approval.”

AveXis announced a month ago that it was launching its pivotal study of the therapy.

SMA is triggered by a genetic defect that derails a protein needed for motor neurons. AveXis’ therapy is designed to penetrate the blood brain barrier and introduce corrected copies of that gene to fix the problem in SMA1, an infantile form of the disease that becomes apparent in the first 6 months, making it a particularly good target for gene therapy work.

Brian Kaspar

“These kids always go down,” says AveXis CSO Brian Kaspar, who took a leave from his post at the gene therapy center at Nationwide Children’s Hospital in Columbus to spearhead the clinical work. “They never gain milestones, no motor function milestones. They won’t sit unassisted; they’ll never achieve the ability to roll over or stand and walk.”

Given its target, and the lesser effect that Spinraza has demonstrated in the clinic, regulators are likely to feel considerable pressure to open the door early on this therapy, particularly given the preferred treatment that Sarepta gained for Exondys51 without any actual data the it helped boys suffering from Duchenne MD.

New FDA commissioner Scott Gottlieb has vowed to do what’s necessary to make cutting edge therapies available as soon as they’ve cleared a bar on efficacy and safety. And he now has a test case for just where that line has been drawn.


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