Novartis-bound AveXis posts early look at data from pivotal SMA gene therapy trial

Illustration of three DNA helices
The early data from AveXis pivotal trial map onto results from a prior, successful study. (Darwin Laganzon)

AveXis has posted an early look at data from a pivotal trial of its spinal muscular atrophy (SMA) gene therapy. The neuromuscular scores of the first group of patients improved as expected over the early months of the study, raising hopes the Novartis-bound gene therapy will deliver positive data.

Bannockburn, Illinois-based AveXis is still a long way from turning those hopes into solid evidence, but the trial is on track. The neuromuscular scores of the first six patients enrolled in the study increased by 7.8 on average after one month, as compared to a rise of 9.8 in the successful phase 1. The numbers after three months were 17.3 and 15.4, respectively. AveXis has three-month data on three patients in the phase 3.

Given the phase 3 patient population and early data map onto those of the prior study, there are reasons to think some of the participants will be sitting independently and living without intense, prolonged ventilator use by the end of the trial. If enough participants are in that state, the trial will hit its co-primary efficacy endpoints.

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Enrollment in the trial is ongoing. AveXis will enroll 15 symptomatic SMA patients aged six months or younger and follow them for 18 months after they receive a single intravenous infusion of its gene therapy AVXS-101. The therapy is designed to fix the root cause of SMA by giving recipients a fully-functional human SMN gene. The presence of such a gene should increase production of the SMN protein, thereby improving motor neuron function.

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While working to validate that idea in a pivotal trial, AveXis is also gathering long-term data on the participants in its phase 1 trial. All 15 patients are living without permanent ventilation two years after treatment. These children are now around 30 months old, an age many people with untreated SMA Type 1 never reach.

AveXis reported continued improvement in the 12 patients who received the high dose in the earlier study. All but one of the kids can now sit unassisted for 30 seconds or more. One-third can stand with assistance. 

These long-term outcomes will come into play when Novartis, which is set to gain control of the gene therapy through an $8.7 billion deal, needs to persuade people to pay for the treatment.