Onasemnogene Abeparvovec: First Global Approval

Onasemnogene abeparvovec (onasemnogene abeparvovec-xioi; formerly AVXS-101; ZOLGENSMA^®) is an adeno-associated viral vector-based gene therapy designed to deliver a functional copy of the human survival motor neuron (SMN) gene to the motor neuron cells of patients with spinal muscular atrophy (SMA). It has been developed by AveXis, a Novartis company, and was approved in May 2019 in the USA for the treatment of paediatric patients aged < 2 years with SMA and bi-allelic mutations in the SMN1 gene (the primary gene encoding survival motor neuron protein). Onasemnogene abeparvovec is the first gene therapy to be approved for SMA in the USA. The recommended dose is 1.1 × 10¹⁴ vector genomes per kg of bodyweight, administered as a single intravenous infusion over 60 min. Regulatory assessments for this formulation of onasemnogene abeparvovec are underway in the EU and Japan; an intrathecal formulation is currently undergoing clinical development in the USA. This article summarizes the milestones in the development of onasemnogene abeparvovec leading to this first approval for the treatment of paediatric patients aged < 2 years with SMA and bi-allelic mutations in SMN1.