Enzyme replacement therapy for mucopolysaccharidosis VI: a phase 3, randomized, double-blind, placebo-controlled, multinational study of recombinant human N-acetylgalactosamine 4-sulfatase (recombinant human arylsulfatase B or rhASB) and follow-on, open-label extension study.

Objective The objective of this Phase 3 study was to confirm the efficacy and safety of recombinant human arylsulfatase B (rhASB) treatment of mucopolysaccharidosis type VI (MPS VI; Maroteaux-Lamy syndrome), a rare, fatal lysosomal storage disease with no effective treatment. Study design Thirty-nine patients with MPS VI were evaluated in a randomized, double-blind, placebo-controlled, multicenter, multinational study for 24 weeks. The primary efficacy variable was the distance walked in a 12-minute walk test (12MWT), whereas the secondary efficacy variables were the number of stairs climbed in a 3-minute stair climb (3MSC) and the level of urinary glycosaminoglycan (GAG) excretion. All patients received drug in an open-label extension period for an additional 24 weeks. Results After 24 weeks, patients receiving rhASB walked on average 92 meters (m) more in the 12MWT ( p = .025) and 5.7 stairs per minute more 3MSC ( p = .053) than patients receiving placebo. Continued improvement was observed during the extension study. Urinary GAG declined by -227 ± 18 μg/mg more with rhASB than placebo ( p Conclusion rhASB significantly improves endurance, reduces GAG, and has an acceptable safety profile.