The majority of babies with spinal muscular atrophy (SMA) treated with onasemnogene abeparvovec (Zolgensma®) gained at least 1 World Health Organization (WHO) motor milestone, according to a prospective cohort study conducted in Australia. Moreover, the bulbar or respiratory function of almost all treated babies stabilized or improved.

However, transient treatment-related side effects occurred in all of the children. The incidence of moderate to severe transaminitis was significantly greater in babies weighing 8 kg or more than in those weighing less than 8 kg. 

“This study provides real-world evidence to inform treatment decisions and guide therapeutic expectations for onasemnogene abeparvovec and combination therapy for SMA in health practice, especially for children weighing ≥8 kg receiving higher vector loads,” the authors of the study wrote. “Proactive clinical and laboratory surveillance is essential to facilitate individualized management of risks.”

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Onasemnogene abeparvovec is the first approved gene therapy for SMA and the second disease-modifying treatment, after nusinersen (Spinraza®).

Read more about onasemnogene abeparvovec (Zolgensma®)

To gain a better understanding of the safety, tolerability, and clinical outcomes of the treatment in real-world practice, a team of researchers led by Michelle A. Farrar, PhD, of the Department of Neurology, Sydney Children’s Hospital Network in Australia conducted a prospective cohort study of children with SMA between August 2019 and November 2021. 

During this time period, 21 children with SMA who were aged 0 to 2 years and weighed between 2.5 and 12.5 kg were treated with onasemnogene abeparvovec at the Sydney Children’s Hospital Network. Of these, 19 had been treated with nusinersen previously.

Vomiting occurred in all babies treated with onasemnogene abeparvovec. Transaminitis occurred in 57% of them and thrombocytopenia occurred in 33%.

The mean duration of prednisolone treatment following onasemnogene abeparvovec treatment was 87.5 days.

The challenges of implementation were reduced through the development of standard operating procedures and by facilitating the exchange of knowledge.

“Importantly, this study also describes the clinical translation of a model of care for SMA patients, including challenges associated with establishing appropriate infrastructure, delivery and medical management during the COVID-19 pandemic, across multiple jurisdictions,“


D’Silva AM, Holland S, Kariyawasam D, et al. Onasemnogene abeparvovec in spinal muscular atrophy: an Australian experience of safety and efficacy. Ann Clin Transl Neurol. Published online February 16, 2022. doi:10.1002/acn3.51519