Liquid Therapy RG7916 Improves Protein Levels for Infants with SMA

Giovanni Baranello, MD, PhD

An investigational once-daily liquid drug may be able to improve protein levels in infants with spinal muscular atrophy (SMA).

An open-label study of RG7916, a solution designed to modulate the survival motor neuron 2 (SMN2) gene splicing in order to increase SMN protein, has reported that infant levels of SMN protein increased up to 6.5 times after 4 weeks of treatment compared to baseline levels. The data will be presented at the 70^th annual meeting of the American Academy of Neurology (AAN) in Los Angeles, CA, next week.

SMA is an inherited condition that results in the loss of motor function and potential mortality in infants and toddlers. It is currently the leading genetic cause of death in both age groups, and is caused by reduced levels in the SMN protein. Because the SMN1 gene in patients with SMA is either mutated or missing, the backup SMN2 gene is resolved to produce some of the necessary protein.

RG7916’s aid in increasing the protein has shown early promise in pediatric patients. The study from researchers at the Carlo Besta Neurological Institute in Milan, Italy involved 21 babies, aged 3-7 months old, with type 1 SMA who have 2 copies of the SMN2 gene.

Patients were administered the therapy daily for 4 weeks, at different dose levels. Over time, patient SMN protein levels in their blood increased, with an association found between greater dosage and greater protein rates. Nineteen of the infants were still alive at the time of analysis, with 2 deaths reported as disease-related, but not linked to the effects of the drug. Study duration averaged 4 months in the 19 infants, with a range from 1-13.5 months.

Adverse events generally reported in liquid therapy — such as losing the ability to swallow, or requiring a tracheostomy or breathing support — were not reported in this initial study, and there were no reported safety problems that required infant participants to be removed from therapy.

Study author Giovanni Baranello, MD, PhD, at the Carlo Besta Neurogical Institute, said in a statement that this was the first such study designed to assess RG7916’s safety and dosage rates — not its efficacy. That said, its effect has generated hope in the team.

“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,” Baranello said. “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.”

The second phase of the study, which has already begun, is currently recruiting participants and will focus on RG7916’s efficacy.

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