Efficacy and safety of idursulfase beta in the treatment of mucopolysaccharidosis II: A phase-3, 2-part study compared with a historical placebo cohort.

PURPOSE: To investigate the efficacy and safety of idursulfase beta (0.5 mg/kg weekly) in the treatment of mucopolysaccharidosis II, compared with a historical placebo from a previous idursulfase trial (TKT024).

METHODS

The study comprised 2 sequential parts. In part 1, a randomized, double-blind study, idursulfase or idursulfase beta were given for 52 weeks. In the open, single-cohort part 2 study, additional participants received idursulfase beta for 52 weeks. Data from the idursulfase beta groups from parts 1 and 2 were pooled for comparisons with the historical placebo group (n = 32). The primary end point was a change in the 6-minute walk test at week 53.

RESULTS

Participants in the idursulfase beta groups (n = 24) were male Asians (mean age, 12.0 years). Idursulfase beta was superior to placebo in 6-minute walk test improvement (62.2 vs 7.3 m, P < .0001). Decrease in urine glycosaminoglycan excretion (-71.13% vs 21.39%, P < .0001) and reduction in the liver (-26.67% vs -0.80%, P < .0001) and spleen volumes (-26.46% vs 7.2%, P < .0001) were significant. The safety profile of idursulfase beta was satisfactory.

CONCLUSION

Idursulfase beta is a safe and effective treatment option in mucopolysaccharidosis II, addressing crucial somatic ailments presented by patients.