Early treatment of infants with spinal muscular atrophy (SMA) can drastically improve motor function for patients, explained Jill Jarecki, PhD, chief scientific officer at Cure SMA.
Early treatment of infants with spinal muscular atrophy (SMA) can drastically improve motor function for patients, said Jill Jarecki, PhD, chief scientific officer at Cure SMA.
What do we know about the importance of treating early in infants with SMA?
Jarecki: So, SMA is a motor neuron disease. Motor neurons are dysfunctional and eventually lost. Neurons are a cell type that cannot be regenerated once lost. So, we know that it is important to intervene prior to the loss of motor neurons. And for many years, we've known that mouse models of SMA require an early window of treatment for SMN- [survivor motor neuron] enhancing drugs to have full benefit. And in patients, we've known for many years that electrophysiological experiments in SMA Type 1 infants have denervation of muscle approaching 90% by 6 months of age.
So, we believe it's very important that infants are treated presymptomatically through newborn screening. And there's been further clinical trial data and there are clinical trials looking at presymptomatic infants with all of the FDA approved drugs, but the only one that's been peer reviewed and published so far was called the NURTURE trial from Biogen looking at Spinraza [nusinersen].
There, they've shown dramatic benefits over symptomatic treatment. With presymptomatic treatment of infants under 6 months of age, you now have a Type 1 infant who would not sit, typically not be able to eat on their own, and need extensive respiratory support. Now, 100% of those babies treated presymptomatically are sitting, 100% are crawling, 100% are standing, and 88% are walking independently.
So, there really are dramatic gains with presymptomatic treatment was Spinraza. And we expect to see the same with the other SMN upregulating drugs when those results are published.