Huntington’s Disease Drug Shows Promise in Phase II/III Trial
Treatment slows loss of muscle control (February 20)
Positive results have been reported from a planned 18-month analysis of an ongoing 3-year phase II/III clinical trial of RP103 (delayed-release cysteamine, Raptor Pharmaceutical Corp.) for the potential treatment of Huntington’s disease (HD).
A total of 96 patients with HD were randomly assigned to treatment with RP103 or placebo. Eighty-nine patients completed the initial 18-month phase.
Analysis of all 96 patients enrolled in the trial showed a positive trend towards slower progression of the Total Motor Score (TMS) in patients treated with RP103 compared with those given placebo (the study’s primary endpoint). TMS progression was 32% slower in the RP103 group versus the placebo group after 18 months of treatment (4.51 points vs. 6.68 points, respectively; P = 0.19).
Because of the 36-month duration of the study, the patients were allowed to continue their baseline medication regime, including antidepressants and tetrabenazine, the latter being an approved medication to treat chorea associated with HD.
To confirm that the TMS results were not influenced by a potential treatment effect of tetrabenazine on chorea (a subscore of TMS), the subset of patients not receiving tetrabenazine were analyzed for TMS. In these 66 patients (34 treated with RP103 and 32 given placebo), treatment with RP103 resulted in 58% slower progression in TMS of 2.84 points compared with 6.78 points for placebo at 18 months. This difference was statistically significant (P = 0.03).
Source: Raptor Pharmaceutical Corp.; February 20, 2014.