Crystal Proud, MD: Nancy, the NURTURE clinical trial evaluated treatment of pre-symptomatic, genetically diagnosed infants. Can you review the implications of this study as we conceptualize the implementation of newborn screening for SMA [spinal muscular atrophy]?
Nancy L. Kuntz, MD: Absolutely. This was a very exciting study that was open-label and had 25 infants who had genetic confirmation in the newborn period of their SMA. Most of them had 2 copies of the SMN2 gene, but there was a subset that had 3 copies. All these infants were treated before 6 weeks of age with the beginning of their loading dose, and all of them had no detectable symptoms at that time. The response, clinically, was much more robust than even in the ENDEAR study that you heard described by John. It’s one of the things that made us all begin paying attention to the timing of treatment being important in terms of the benefit.
Of these children, all of them began sitting independently, and the majority of them walked independently. Again, there's still ongoing follow-up. What I'm reporting to you are data that had been presented at the end of 2019. What was even more impressive, rather than saying that they ever sat independently or walked independently, was looking at the age at which these things were accomplished.
In fact, of the whole group, all sat independently, but almost 90% of them sat by age-appropriate timing. Using the WHO [World Health Organization] percentiles for the time at which these milestones are achieved, 73% of them walked independently by age-appropriate milestones. This was, in addition to the fact that they had a very good safety profile, was a very positive benefit. This speaks to the potential outcomes for the children who might receive this therapy for a newborn screening, who all potentially would have the ability to receive treatment by 6 weeks of age.