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Spinal Muscular Atrophy Drug Appears Effective for Older Babies

March 05, 2021

The gene therapy drug onasemnogene abeparvovec for spinal muscular atrophy appears efficacious and well tolerated in infants older than 7 months, according to a study published online ahead of print in Pediatric Neurology. 

“Onasemnogene abeparvovec was recently approved for the treatment of spinal muscular atrophy in children under 2 years; however, clinical trials were primarily completed in children less than 7 months,” wrote clinicians from Children’s Hospital of Philadelphia, “and so practical experience dosing older children began in summer 2019.”

The authors reported on safety and efficacy of onasemnogene in seven infants with spinal muscular atrophy treated at the children’s hospital.

All seven infants showed motor improvements within 3 months of onasemnogene infusion, according to the study. In patients followed longer, clinicians observed continued progress.

“Side effects were similar to those previously reported,” the authors wrote, “although more common and in some cases more severe and more prolonged than seen in the original trials.”

Two to 3 days after infusion, six of the seven infants demonstrated acute viral symptoms with emesis and/or fever, according to the paper. Thrombocytopenia occurred in four patients. Additionally, six patients needed prolonged steroid courses for persistently elevated liver enzymes, one of whom had to be escalated to intravenous steroids.

“The impact of age, weight, and other confounding factors on development of side effects,” the authors noted, “still needs to be elucidated.” 

Jolynn Tumolo


Matesanz SE, Battista V, Flickinger J, Jones JN, Kichula EA. Clinical experience with gene therapy in older spinal muscular atrophy patients [published online February 5, 2021]. Pediatr Neurol. doi:

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