FDA Granted Orphan Drug Status to Stiff Person Syndrome Drug
The FDA designated Qivigy for treatment of this rare neurological disorder, allowing for a new phase 3 study.
Updated on Sept. 25, 2026 in Autism
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The Food and Drug Administration has granted Orphan Drug designation to Qivigy for the treatment of stiff person syndrome. This status supports the development of the immune globulin intravenous solution for patients affected by the autoimmune disorder.
Why it matters
Stiff person syndrome is an autoimmune neurological condition characterized by muscle rigidity and spasms that significantly impact mobility. This designation may accelerate the evaluation of an intravenous therapy designed to improve movement and reduce stiffness in those living with the disorder.
A phase 3 clinical trial is currently evaluating the safety and efficacy of Qivigy in 38 adult participants over a 24-week study duration. Researchers are using the Timed 25-Foot Walk test as a primary endpoint to measure changes in mobility among those with the rare condition.
The players
Food and Drug Administration
The federal agency responsible for regulating pharmaceuticals and ensuring the safety and efficacy of new medical treatments.
The details
Qivigy is an immune globulin intravenous 10% solution that acts by providing donor-derived antibodies to modulate the immune system. Administered via infusion over 2 to 5 days at 4-week intervals, the therapy aims to mitigate the immune-driven neurological damage causing muscle spasms. By receiving Orphan Drug designation, the clinical investigation into its impact on patient mobility and stiffness is now a formal regulatory priority.
Timeline
September 22, 2026: FDA granted Orphan Drug designation.
Health Landscape
The development of this immune-modulating therapy reflects a shift in the standard of care for autoimmune neurological disorders toward targeted antibody-based interventions. The study marks an expansion in the clinical pipeline for stiff person syndrome, moving beyond existing protocols studied at the Stiff Person Syndrome Center.
Individuals managing stiff person syndrome should consult their neurologist about how ongoing clinical trials may fit into their current treatment plan. Discuss with your physician whether this or other immune-modulating therapies are appropriate for addressing your specific symptoms.
The takeaway
Orphan Drug designation serves as a key milestone in bringing new, specialized treatments for rare autoimmune neurological conditions to the market. Patients and caregivers should continue to monitor updates on clinical trial progress to understand new options for managing muscle rigidity.
Further reading
Learn more about the latest research and support resources in our Autism section.
More information
Read the full details regarding this regulatory development in the Kedrion news release.
Source note: This article includes information reported by MPR.
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