Briefs · Frontier Science
For Decades, SMA Was Treated by Fixing the Gene. Now Medicine Has Started on the Muscle.
For decades, spinal muscular atrophy was treated by fixing the gene. Now medicine has started on the muscle.
The FDA approved Isembyld (apitegromab-mstn) on 11 September, the first therapy for SMA that directly targets muscle loss. It is a monoclonal antibody that blocks myostatin, the body’s own brake on muscle growth, and it is given alongside existing SMN2-targeted treatments — not instead of them — to adults and children aged two and over.
The evidence comes from the Phase 3 SAPPHIRE trial: 188 patients, 52 weeks, and a 2.2-point gain on the Hammersmith motor scale over placebo, with treated patients gaining function while those on SMN2 therapy alone declined. A third of treated patients improved by three points or more, against one in eight on placebo.
Conclusion: Isembyld is not a replacement for gene therapy, but rather its muscle — and for the first time, SMA treatment has both.
Read the original at U.S. Food and Drug Administration
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