• A new clinical trial will study whether a higher dose of nusinersen will help people with spinal muscular atrophy (SMA).
• The trial will begin enrolling participants this year.
• Trial participants must be between the ages of 5 and 39, have later-onset SMA, and have already been treated with risdiplam.

A new worldwide clinical trial will test the safety and efficacy of higher doses of nusinersen, sold under the brand name Spinraza, for people with spinal muscular atrophy. The ASCEND study will include children, teens, and adults with SMA.

ASCEND will study the effects of higher doses of nusinersen in people who have previously been treated with risdiplam, which is sold under the brand name Evrysdi. Researchers are hoping to enroll participants in 2021. The study is planned to last 2.5 years.

The goal is to include as many as 135 participants between the ages of 5 and 39 years who have later-onset nonambulatory SMA. Each must have taken risdiplam before. During the study, the participants will be given two initial 50-milligram doses of nusinersen two weeks apart, and then they will take 28-milligram doses every four months for the rest of the study.

Nusinersen was approved in 2016 by the U.S. Food and Drug Administration (FDA) to treat SMA types 1, 2, and 3. Currently, the FDA-approved dose of nusinersen is 12 milligrams, which is injected into the fluid surrounding the spinal cord (known as an intrathecal injection).

Doctors and researchers hope that increasing the dose of nusinersen can help fill the gaps in treatment in people treated with risdiplam. Current research suggests the concentration of risdiplam in the body decreases as people grow and age, making the medication less effective over time. A risdiplam dose is capped at 5 milligrams once a child weighs around 44 pounds.

Dr. Maha Radhakrishnan, chief medical officer at Biogen, said in a press release, “We believe that lower drug exposure may be contributing to less-than-optimal treatment outcomes for some patients treated with Evrysdi. The ASCEND study seeks to understand if nusinersen may address that unmet medical need and will help inform the future of SMA treatment, with the hope of improving patients’ outcomes for the long term.”

Due to nusinersen’s relatively recent FDA approval, researchers are continuing to examine the long-term effects of the medication. One study of 20 infants with SMA has measured the effects of nusinersen treatment over three years. Researchers found that nusinersen improved survival and helped the infants reach developmental milestones over the duration of the study.