A preliminary, open-label study presented at the American Academy of Neurology’s 70th Annual Meeting (April 21–27, CA, USA) has revealed that an investigational drug may help increase protein levels in babies with spinal muscular atrophy (SMA).
SMA is the leading genetic cause of death in infants and toddlers and is caused by a reduction in SMN protein levels. In SMA, the SMN1 gene is either mutated or missing. To override this, the SMN2 gene can act as a backup to allow production of some of the necessary protein.
The novel drug – termed RG7916 – is a liquid solution given orally once a day and is designed to modulate SMN2 splicing to increase SMN protein levels.
Babies with type 1 spinal muscular atrophy were included in the study, all of whom contained two copies of the SMN2 gene. On average, these babies were understood to survive for 10.5 months before death or the need for permanent breathing support.
In the first phase of the study, 21 babies aged 3–7 months old were included at the start. They received a daily dose of the drug for 4 weeks at varying dose levels.
Results from the study demonstrated an increase of the SMN protein in blood, with greater increases for higher doses of the drug. Protein levels were up to 6.5-times higher after 4 weeks of treatment for the highest dose group compared with levels at the beginning of the study.
At the time of analysis, 19 babies were alive – two fatal events were reported but were considered disease-related and not related to the investigational drug.
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“These results are exciting, as children with SMA type 2, which is less severe than type 1, have approximately twice as much SMN protein as those with type 1 so to see an increase of up to 6.5-times the amount of protein is very encouraging and supports the possibility to see improved function in these babies,” commented Giovanni Baranello (Carlo Besta Neurological Institute, Milan, Italy), one of the authors of the study. “This research is continuing and much more needs to be done to determine whether this treatment will provide meaningful benefits for children with spinal muscular atrophy.”
To conclude, Baranello noted that the first phase of the study was designed to assess the safety of the treatment and to find the right dose for the babies – cautioning that it was not designed to determine how effective the treatment was. This will be assessed in the second phase of the study, which has started and is currently recruiting study participants.