What this study looked at
Alpha-mannosidosis (AM) is a rare inherited lysosomal storage disorder caused by a deficiency of the enzyme alpha-mannosidase. This was a phase III trial, with a follow-on extension, designed to test the efficacy and safety of velmanase alfa: 25 patients were randomly assigned to weekly infusions of the enzyme or placebo for a year, after which the placebo group also switched to active treatment.
Key takeaways
- Patients treated with velmanase alfa had a marked fall in serum oligosaccharides — a measure of the stored material — of around 78% at one year, a benefit that was maintained over longer follow-up.
- Movement, assessed by a three-minute stair-climb test, showed clearer improvement over time and once placebo patients had switched to active treatment.
- Analysis of baseline factors found that, apart from age, none predicted how well a patient would respond to treatment.
Why it matters
The trial supports velmanase alfa as a treatment for alpha-mannosidosis, with benefit becoming more evident over time and when therapy is started in childhood.
