• Nusinersen, sold as Spinraza, has been shown to prevent decline in breathing abilities in some infants with spinal muscular atrophy (SMA) type 1.
• In a recent study, none of the infants receiving the treatment showed signs of improvement in their breathing after two years of treatment.
• Researchers concluded that further real-world study is necessary to determine if starting treatment earlier will have better outcomes.

Infants with SMA type 1 treated with nusinersen can maintain the same level of breathing or respiration over two years, according to a new study. Typically, infants with SMA type 1 — the most severe form of the condition — experience a rapid decline in their breathing abilities as the condition progresses. The median survival for infants with SMA type 1 is 8 to 13.5 months. Respiratory failure is the most common cause of death.

Sold as Spinraza, nusinersen is the first disease-modifying therapy for SMA. It was approved by the U.S. Food and Drug Administration (FDA) in 2016.

For the study — conducted by Dr. Moran Lavie and their colleagues at Tel Aviv University in Israel — 20 infants with SMA type 1 were assessed both before and after two years of nusinersen treatment. Among the participants, 16 infants were already on assisted ventilation at the start of the study; the other four were not.

During the two years, the researchers observed several outcomes. These included:

• All of the participants who were on ventilation when they started treatment remained clinically stable, maintaining a similar level and type of ventilatory support.
• The four infants who were not on ventilation needed to start ventilation.
• Two infants died from acute respiratory failure.
• One infant sustained a severe brain injury.
• Four of the infants had recurrent or chronic collapse of the lung.

“Our experience was that most patients were stable in their need for assisted ventilation and did not worsen as expected given the natural history of the disease, nor did they improve as one would hope,” the authors of the study wrote.

They noted that further studies are necessary to see whether starting treatment with nusinersen earlier might lead to better respiratory outcomes.