Gene Therapy for Spinal Muscular Atrophy: Safety and Early Outcomes

Megan A. Waldrop, MD,a,b Cassandra Karingada, MSN,c Mike A. Storey, PharmD, PharmD,d Brenna Powers, DPT,b Megan A. Iammarino, DPT,b Natalie F. Miller, DPT,b Lindsay N. Alfano, DPT,b Garey Noritz, MD et al

PEDIATRICS Volume 146, number 3, September 2020:e20200729

BACKGROUND AND OBJECTIVES:

Historically, autosomal recessive 5q-linked spinal muscular atrophy (SMA) has been the leading inherited cause of infant death. SMA is caused by the absence of the SMN1 gene, and SMN1 gene replacement therapy, onasemnogene abeparvovec-xioi, was Food and Drug Administration approved in May 2019. Approval included all children with SMA age ,2 years without end-stage weakness. However, gene transfer with onasemnogene abeparvovec-xioi has been only studied in children age <8 months.

METHODS:

In this article, we report key safety and early outcome data from the first 21 children (age 1–23 months) treated in the state of Ohio.

WHAT’S KNOWN ON THIS SUBJECT:

Spinal muscular atrophy is an inherited neurodegenerative neuromuscular disease. There are now two safe and highly effective Food and Drug Administration–approved genetic therapies. However, the Food and Drug Administration indications were much broader than those assessed in clinical trials.

WHAT THIS STUDY ADDS:

In this retrospective review, we report the safety and early efficacy of onasemnogene abeparvovec-xioi in all spinal muscular atrophy patients aged ,2 years within Ohio regardless of phenotype.

CONCLUSIONS

Onasemnogene abeparvovec-xioi was well tolerated in all children treated in the state of Ohio. Our experience suggests that when a thorough screening process is completed, social isolation is implemented to minimize the risk of illness after gene transfer, and patients are monitored closely in the weeks to months after gene transfer, adverse events are few. We do recommend delaying gene transfer until complete resolution of preexisting viral illnesses.