Long-term clinical effects of enzyme replacement therapy in MPS II

Background
We report clinical results of long-term enzyme replacement therapy in Polish population of patients with mucopolysaccharidosis type II (MPS II). The therapy was deemed ineffective and was discontinued in the majority of them but reaching the consensus on ineffectiveness of enzyme replacement required often several years.

Methods
The standard clinical monitoring parameters such as: six-minute walking test, pulmonary function tests, severity of organomegaly and of heart dysfunction, proved to be hardly helpful in many cases. This was caused by young age of patients, their physical and intellectual disabilities as well as by various disease courses.

Results
On contrary, linear growth and body weight dynamics proved to be useful indicators of the presence or absence of an overall anabolic effect of enzymatic therapy. However, proper growth pattern in affected children or significant body weight increase in already adult patients were rare and could be detected in less than 50% of milder cases only. No such effects were observed in patients with more severe disease form.

Conclusion
In our opinion, body weight dynamics is a useful clinical indicator of treatment responsiveness in patients with MPS II.