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FDA Approves Rare Infant Disease Gene Therapy

Neurons
(commonfund.nih.gov)

24 May 2019. The Food and Drug Administration today approved a treatment for spinal muscular atrophy in young children that replaces a faulty gene in motor neurons with a healthy one. The approved therapy is sold under the name Zolgensma, made by AveXis in Basel, Switzerland, a company owned by drug maker Novartis.

Spinal muscular atrophy or SMA is an inherited condition in infants where specialized motor nerve cells in the spinal cord and brain stem are missing, leading to wasting away of muscles for crawling, walking, sitting up, and head movements. In severe cases, muscles for breathing and swallowing can also be affected. The disease is caused by a mutation in survival motor neuron 1 or SMN1 gene that encodes for a protein needed for healthy functioning of motor neurons or nerve cells.

“Most children with this disease do not survive past early childhood due to respiratory failure,” says Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, in an agency statement. “Patients with SMA now have another treatment option to minimize the progression of SMA and improve survival.”

Zolgensma uses a benign virus, called an adeno-associated virus, given as a single infusion to deliver a healthy SMN1 gene copy into targeted motor neurons that produces the functioning proteins needed by children with SMA. FDA approved Zolgensma in part on results from clinical trials in the U.S. and Europe showing children less than 2 years in age receiving the healthy gene showing more improvement in meeting motor function milestones than children with SMA typically demonstrate, such as controlling head movements or sitting up on their own. The U.S. trial is still underway.

FDA approved Zolgensma for children up to the age of 2 years. The most common adverse effects of the treatments, says the agency, are elevated enzymes and vomiting. FDA requested a boxed warning be included alerting of serious liver damage, particularly in patients with a compromised liver. The agency previously designated Zolgensma as an orphan drug, gave it a “breakthrough” tag, and assigned the biologic therapy priority and fast-track accelerated reviews.

The list price for a Zolgensma treatment is set by AveXis at $2,125,000. The proposed prices received push-back last month from Institute for Clinical and Economic Review, or ICER, an independent group that analyzes drug effectiveness and value, calling them “above commonly accepted cost-effectiveness thresholds.” A statement today from ICER says new clinical trial data show longer-lasting effects of Zolgensma treatments, and as a result, “the price announced today falls within the upper bound of ICER’s value-based price benchmark range.”

AveXis was acquired by Novartis in April 2018 for $8.7 billion, as reported by Science & Enterprise. The company says it is working with insurance companies to work out 5-year repayment and outcomes-based plans for Zolgensma.

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