Patients with spinal muscular atrophy (SMA) treated with a one-time infusion of onasemnogene abeparvovec-xioi (Zolgensma®; AveXis) continue to show clinically meaningful benefits even 5 years after dosing, according to new data from the STR1VE-US, SPR1NT, and START trials.

Results from the pivotal open-label, single-arm, phase 3 STR1VE-US study evaluating onasemnogene showed that patients aged <2 years with SMA Type 1 experienced rapid, sustained and clinically meaningful improvements in motor function. Findings from the study demonstrated that 91% of patients (n=20/22) achieved event-free survival (co-primary end point) at 14 months, and 59% (n=13/22) achieved independent sitting for ≥30 seconds (co-primary end point) at 18 months. Moreover, 40.9% of patients (n=9/22) showed the “ability to thrive” (secondary end point) at 18 months, defined as not receiving nutrition through mechanical support or other non-oral method, having the ability to tolerate thin liquids, and being able to maintain weight.

Interim data from the ongoing open-label, single-arm, phase 3 SPR1NT study, which evaluated the efficacy and safety of onasemnogene in 29 pre-symptomatic infants aged <6 weeks with SMA and 2 or 3 copies of survival motor neuron 2 gene (SMN2), showed that among patients with 2 copies of SMN2, 7 out of 8 patients achieved the ability to sit independently (primary end point) within the World Health Organization (WHO) window of normal development. The 6 remaining patients in this cohort of 14 who have not yet passed are still within the developmental window. Most patients were within age-appropriate weight range and were fed orally; none of the patients required ventilatory support.

Lastly, new data from the long-term START study, which evaluated the efficacy and safety of onasemnogene in 12 SMA Type 1 patients with onset of clinical symptoms before 6 months of age, showed that all of the study participants were alive 5 years post-dose, free of permanent ventilation, and continued to maintain developmental milestones (2 patients achieved the new milestone of standing with assistance). 


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“In complete contrast to the natural course of the disease, patients who received Zolgensma soon after birth before the onset of symptoms are achieving age-appropriate motor milestone development – an extraordinary outcome for SMA patients,” said Olga Santiago, MD, Chief Medical Officer, AveXis. “These SPR1NT data demonstrate the truly transformational impact a one-time dose of gene therapy can have, and further underscore the importance of newborn screening and early intervention to alter the course of the disease.”

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The STR1VE-US study findings were presented during a virtual Clinical Trial Session conducted by the Muscular Dystrophy Association (MDA) after the cancellation of the 2020 MDA Annual Conference due to COVID-19. Data from the SPR1NT and START studies will be published online by MDA in the coming weeks.

Zolgensma is currently approved for the treatment of pediatric patients <2yrs of age with SMA with bi-allelic mutations in the SMN1 gene.

For more information visit avexis.com.

This article originally appeared on MPR