New Drug Under Review by the FDA to Treat the Most Lethal Form of Spinal Muscular Atrophy


According to an article in Biospace, the FDA is currently reviewing data from the Phase III STRIVE clinical trial for possible approval of Zolgensma as gene therapy for spinal muscular atrophy (SMA) type 1. The drug is being developed as a one-time infusion.

Two Infant Deaths

The first of two recent infant deaths occurred during the STRIVE study six months after infusion of Zolgensma. An independent safety board determined that this first death was unrelated to the drug.

A second infant death occurred recently during a European study of Zolgensma. The company responsible for the drug, AveXis, had just released its third term interim data to facilitate FDA approval of Zolgensma.

The six-month-old infant had been diagnosed with type 1 spinal muscular atrophy which is characterized among other symptoms by difficulty swallowing and breathing. An investigation is being conducted to determine whether this second Zolgensma-related death is in any way associated with the drug.

About Spinal Muscular Atrophy (SMA)

Spinal muscular atrophy (SMA) is a rare disease that affects about one in ten thousand babies. It is characterized by loss of motor neurons that cause muscle weakness, atrophy (loss of movement) and possible paralysis.

SMA consists of a group of genetic neuromuscular disorders affecting the nerve cells that control muscles. Breathing and swallowing may be affected as the disease progresses.

There are four types of SMA. Type 1 is the most lethal. Each type of SMA differs in that the disease may begin at various stages such as before birth, childhood or young adulthood.

According to Novartis’ estimate, without proper treatment, fifty percent of babies with type 1 SMA will either need permanent breathing support or may not live longer than ten months.

The disease is inherited through one gene from each parent (autosomal recessive). Diagnosis of SMA is confirmed through genetic testing. Physical therapy and physiotherapy of the chest are standard treatments but ventilators (machines to aid breathing) may be required in some cases.

Zolgensma Clinical Trials

The first clinical trial and submission to the FDA consisted of fifteen infants who received Zolgensma gene therapy. This trial was expanded so that the interim data now includes twenty-two infants who had been diagnosed with type 1 SMA.

The results of the trial were positive with an improvement in movement and also the ability to sit up.

The Cost

Zolgensma’s price per therapy is dependent upon approval by insurers.  A rough estimate by the parent company, Novartis, is that it would be cost effective at about $4 or $5 million for each therapy.

The only drug currently on the market that is approved to treat all types of SMA is Biogen’s Spinraza, at a cost of $750,000 in the first year of treatment and then at $375,000 for subsequent years.

Recently an organization that reviews drug pricing deemed Spinraza as too highly priced compared to its value.  The agency believed that if approved, Zolgensma would also be priced well above its value.

It is not surprising that the companies disagree with these findings. A spokesman for Novartis said that they are looking at options such as “pay-over-time”.

As for Spinraza, Biogen stressed the importance of its having a longer period of data with a significant number of patients throughout the world.


Rose Duesterwald

Rose Duesterwald

Rose became acquainted with Patient Worthy after her husband was diagnosed with Acute Myeloid Leukemia (AML) six years ago. During this period of partial remission, Rose researched investigational drugs to be prepared in the event of a relapse. Her husband died February 12, 2021 with a rare and unexplained occurrence of liver cancer possibly unrelated to AML.

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