September 2026 Research Update

This month brought real-world evidence that velmanase alfa (an enzyme replacement therapy) was linked with broad stability or improvement in alpha-mannosidosis symptoms over follow-up, rather than gradual worsening. In a French registry group, doctors reported better motor function and day-to-day wellbeing, and many different symptom areas were described as either improved or unchanged after starting therapy. The overall picture was improvement in several domains with no reported overall deterioration in the listed manifestations, alongside expected practical issues like side effects in some people. [1]

The registry report described large average improvements in physician-rated motor, quality-of-life, and psychological domains from before treatment to the last follow-up. Across the different clinical manifestations tracked in the charts, about half were described as improved and the rest as stable, and none were described as worse at last follow-up. The study also noted that earlier start age and longer time on treatment were linked with better reported outcomes, which fits the idea that timing and continuity may matter, though this kind of data cannot prove cause and effect. [1]

Alongside clinical observations, the report described laboratory changes consistent with the treatment doing what it is designed to do, including lower oligosaccharides (storage products) and higher IgG levels. Safety reporting showed that treatment-related side effects occurred in 3 of the 16 patients; one patient had two severe infusion reactions (swelling of the eyelids and tongue, and a rash) that led to stopping velmanase alfa, and the treatment-related events were reported as resolved. Because this was a small retrospective chart review, the amount and type of follow-up information varied between patients, and some assessments were not standardized. [1]

For patients and caregivers, this adds a clearer picture of what velmanase alfa can look like outside of a controlled trial: many people were described as improving or staying stable in movement, daily wellbeing, and psychological health over time. It also highlights that side effects, including infusion reactions, can happen and led one person in this series to stop treatment, even though treatment-related events were reported as resolved. This evidence may matter now mainly as reassurance about real-world patterns, but it is still early and limited because it comes from only 16 people and relies on what was recorded in routine care rather than uniform testing. [1]

What remains uncertain is how closely these results apply to all people with alpha-mannosidosis, especially those with different ages, symptom severity, or access to long follow-up, since some data were missing and the study did not compare against an untreated group. Even with those gaps, the report helps clarify which areas may be tracked over time in everyday life (movement, breathing tests, and day-to-day functioning), and it supports the idea that many manifestations may be at least stabilizable during treatment in routine care observations. [1]