Onasemnogene Abeparvovec-xioi: Gene Therapy for Spinal Muscular Atrophy

To review the efficacy and safety of onasemnogene abeparvovec-xioi (Zolgensma) in the treatment of spinal muscular atrophy (SMA).

An English-language literature search of PubMed, MEDLINE, and Ovid (1946 to December 2019) was completed using the terms onasemnogene, AVXS-101, and spinal muscular atrophy. Manufacturer prescribing information, article bibliographies, and data from ClinicalTrials.gov were incorporated in the reviewed data.

All studies registered on ClinicalTrials.gov were incorporated in the reviewed data.

Onasemnogene is the first agent for SMA utilizing gene therapy to directly provide survival motor neuron 1 (SMN1) gene to produce SMN protein. Four publications of 1 clinical trial, 1 comparison study of treatment effects, and 1 combination therapy case series have been published.

Onasemnogene is a one time dose approved by the Food and Drug Administration for SMA patients <2 years old who possess mutations in both copies of the SMN1 gene.

Onasemnogene appears to be an efficacious therapy for younger pediatric patients with SMA type 1. Concerns include drug cost and potential liver toxicity. Long-term benefits and risks have not been determined.