The revision accounts for data from the NURTURE trial showing that patients with 3 copies of SMN2 greatly benefit from early treatment.
Cure SMA has announced that it has revised its recommendations for treating newborns with spinal muscular atrophy (SMA) to include immediate treatment for those who have 4 copies of the SMN2 gene.1 The revised recommendations were published in the Journal of Neuromuscular Diseases.2
Originally published in May 2018, the recommendations, titled “Treatment Algorithm for Infants Diagnosed with Spinal Muscular Atrophy through Newborn Screening,” had previously recommended immediate treatment for individuals with 2 or 3 copies of SMN2, typically corresponding to the SMA type 1 and 2 clinical phenotypes. At the time, the multidisciplinary working group was unable to reach a consensus on immediate treatment in patients with 4 copies of SMN2, ultimately recommending that the decision to treat be made on a case by case basis with input from health care providers and parents.
The group reconvened in September 2019 after additional data from Biogen’s phase 2 NURTURE trial became available, demonstrating a significantly greater improvement in patients with 2 or 3 copies of SMN2 who were treated at age 6 weeks or younger with nusinersen (Spinraza) compared with treatment after 6 weeks of age.3
Data from the ongoing study, which includes 25 patients who were presymptomatic and likely to develop SMA types 1 or 2, showed that 100% of the infants treated with nusinersen were able to sit without support, 88% were able to walk with assistance, 77% were able to walk independently, and no patients required permanent ventilation assistance — milestones that are not typically documented in the natural history of the disease.3
Notably, multiple subgroups approached the maximum score of 64 on the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND), with those with 3 SMN2 copies (n = 10) scoring a mean 63.4 compared to a mean score of 62.1 for those with 2 SMN2 copies (n = 15).3
“The working group argues the same predicted outcomes would apply for patients with 4 copies of SMN2 as to those with 3 copies,” they wrote in the updated recommendations.2 “With early treatment, disease would be mostly eradicated in presymptomatic patients with 4 copies of SMN2.”
Notably, the working group also revisited their recommendation for watchful waiting for patients with 5 copies of SMN2; however, the group voted to uphold that recommendation at this time.
“Decisions about initiation of treatment, when not done immediately, are still dependent on the presence of any clinical or subclinical signs of SMA, such as weakness or decrease in amplitude of the compound muscle action potential. These symptoms are reflective of already occurring motor neuron dysfunction or loss,” Cure SMA said. “Critically, the Working Group notes that the loss of even a small number of motor neurons is unacceptable when effective treatment is available, as this loss cannot be reversed after onset but can be prevented with earlier treatment.”
The working group did acknowledge that current laboratory assays struggle to distinguish the exact amount of copies of SMN2 when several copies are present. The group recommends that patients follow-up with a laboratory that is able to distinguish the exact number of copies
1. Cure SMA working group revises recommendations for the treatment of infants diagnosed with SMA via newborn screening who have 4 copies of SMN2. Cure SMA. February 15, 2020. curesma.org/cure-sma-recommendations-on-4-smn2-copies/. Accessed February 17, 2020.
2. Glascock J, Sampson J, Connolly AM, et al. Revised recommendations for the treatment of infants diagnosed with spinal muscular atrophy via newborn screening who have 4 copies of SMN2. J Neuromuscul Dis. Published online January 28. 2020. doi: 10.3233/JND-190468.
3. Biogen Announces New Data Further Establishing SPINRAZA® (nusinersen) as a Foundation of Care in Spinal Muscular Atrophy for a Broad Range of Patients [press release]. Cambridge, MA: Biogen. Published July 1, 2019. multivu.com/players/English/8560251-biogen-nurture-study-spinraza-spinal-muscular-atrophy-treatment-data. Accessed February 17, 2020