Novartis AG's AveXis Inc. unit secured the U.S. Food and Drug Administration's approval for its gene therapy to treat a rare genetic disease that leads to progressive muscle weakness and paralysis in children aged less than 2 years.
The company's Zolgensma is the first and only gene therapy approved by the FDA for the treatment of spinal muscular atrophy, or SMA, a genetic neuromuscular disorder caused by a defective or missing survival motor neuron, or SMN1, gene that affects voluntary muscle movement and leads to difficulty in breathing, swallowing, speaking and walking. In its most severe form, or when left untreated, the disease could lead to permanent ventilation or death for most patients by age 2.
The Zolgensma therapy was designed as a one-time treatment to address the root cause of SMA by employing a modified virus to deliver a copy of the survival motor neuron gene to replace the defective one.
"It's a historic advance for the treatment of SMA," Novartis CEO Vas Narasimhan told journalists on a May 24 conference call. "It adds truly transformative impact."
The approval was based on data from an ongoing phase 3 study, named Str1ve, and the completed phase 1 study, dubbed START, which evaluated efficacy and safety of a one-time infusion of Zolgensma in patients with SMA Type 1, that showed symptoms at less than 6 months of age.
Patients treated with Zolgensma showed improved survival rate and rapid motor function, including the ability to sit without support mostly within a month of dosing. Follow-up data from the early-stage study showed that patients who received Zolgensma continued to show improvements nearly four years after receiving the treatment.
The FDA gave Zolgensma priority review designation in December 2018. Zolgensma holds the priority medicines designation in Europe and is being reviewed under accelerated assessment procedure and also has accelerated designation in Japan.
The current 10-year cost of chronic therapy, which is given over the patient's lifetime, can exceed $4 million in just the first 10 years of the patient's life, while the wholesale cost of Zolgensma is about $2.1 million. Novartis offers the ability to pay for the drug in installments over five years, and will also offer rebates if the therapy does not perform as well as expected, Dave Lennon, president of AveXis, said on the conference call.
"Zolgensma sets the new standard of care for the first and only one-time gene therapy for SMA," Lennon said. "We've priced the product at a significant discount versus chronic therapy costs, and introduced flexible options that place a priority on supporting patient access. We're ready to launch with adequate supply."