Effect of nusinersen after 3 years of treatment in 57 young children with SMA in terms of SMN2 copy number or type.

Background: Spinal muscular atrophy (SMA) is a rare genetic neuromuscular disorder due to an autosomal recessive mutation in the survival motor neuron 1 gene (SMN1), causing degeneration of the anterior horn cells of the spinal cord and resulting in muscle atrophy. This study aimed to report on the 36-month follow-up of children with SMA treated with nusinersen before the age of 3 years. Changes in motor function, nutritional and ventilatory support, and orthopedic outcomes were evaluated at baseline and 36 months after intrathecal administration of nusinersen and correlated with SMA type and SMN2 copy number.
Results: We found that 93% of the patients gained new motor skills during the 3 years-standing without help for 12 of 37 and walking with help for 11 of 37 patients harboring three SMN2 copies. No patients with two copies of SMN2 can stand alone or walk. Patients bearing three copies of SMN2 are more likely to be spared from respiratory, nutritional, and orthopedic complications than patients with two SMN2 copies.
Conclusion: Children with SMA treated with nusinersen continue to make motor acquisitions at 3 years after initiation of treatment. Children with two SMN2 copies had worse motor, respiratory, and orthopedic outcomes after 3 years of treatment than children with three copies.
Competing Interests: Declaration of Competing Interest JD, CV, MGGB, and UWL received funding as scientific advisory boards member from Biogen. VL, FA, JD, AI, MCN, JBD, CET, MGGB, and UWL received funding as scientific advisory boards member from Novartis. JD, CC, MGGB, and ID received funding as scientific advisory boards member from Roche. ID received funding as scientific advisory boards member from PTC therapeutics. CC, CET, and UWL received funding as scientific advisory boards member from Pfizer. VL, FA, CB, AI, JBD, CS, and ID received compensations for presentation from Novartis. FA, CB, JBD, CV, and CET received compensations for presentation from Biogen. CC received compensations for presentation from Roche. CS received compensations for presentation from PTC therapeutics and Sanofi Adventis. CC and ID received compensations for presentation from Pfizer. JBD is investigator for ongoing Roche clinical trials. MGGB is sub-investigator in SMA studies for Biogen, Novartis, and Roche. SMD, MC, and MB, declare that they have no competing interests.
(Copyright © 2023. Published by Elsevier Masson SAS.)