Genentech announces four-year follow-up data for Evrysdi in SMA

Genentech announced long-term data for Evrysdi from the open-label extension of the pivotal FIREFISH study, reinforcing its sustained efficacy and safety profile in children with Type 1 spinal muscular atrophy. FIREFISH is a two-part study in babies aged 1-7 months at the time of enrollment. After four years of treatment with Evrysdi, many of the babies, now young children, continued to improve their ability to sit, stand and walk without support. All the Evrysdi-treated children who were alive at the time of the primary analysis were still alive at month 48. Additionally, the majority of infants maintained their ability to feed by mouth and swallow up to month 48. Motor function was assessed by the Gross Motor Scale of the Bayley Scales of Infant and Toddler Development Third Edition and Hammersmith Infant Neurological Examination 2 and abilities were either maintained or improved over four years of Evrysdi treatment. Without treatment, children with Type 1 SMA are not expected to live past two years of age and are never able to sit without support. These data were presented at the Cure SMA Research & Clinical Care Meeting, June 28 – 30, 2023. Among the infants treated with Evrysdi, 37 were able to sit without support for at least 5 seconds at month 48, compared to 35 at month 24. In addition, 36 infants were able to sit without support for at least 30 seconds at month 48, up from 23 infants at month 24. Between month 24 and month 48, three infants gained the ability to stand alone and one infant gained the ability to walk alone. Evrysdi is the first and only small molecule pre-mRNA splicing modifier that targets survival motor neuron-2 for the treatment of SMA, and can be administered at home in liquid form by mouth or by feeding tube. No treatment-related adverse events led to treatment discontinuation or withdrawal from the study, and the rate of AEs decreased by 71% between the first and fourth 12 month periods. The most common AEs were pyrexia, upper respiratory tract infection and pneumonia. The rate of hospitalizations decreased over the study period. Genentech leads the clinical development of Evrysdi as part of a collaboration with the SMA Foundation and PTC Therapeutics.