A Phase 2 Study of AMO-02 (tideglusib) in Congenital and Childhood Onset Myotonic Dystrophy Type 1 (DM1)

Abstract Background GSK3β is an intracellular regulatory kinase that is dysregulated in multiple tissues in Type 1 myotonic dystrophy (DM1), a rare neuromuscular disorder that manifests at any age. AMO-02 (tideglusib) inhibits GSK3β activity in preclinical models of DM1 and promotes cellular maturation as well as normalizing aberrant molecular and behavioral phenotypes. This Phase 2 study assessed the pharmacokinetics, safety and tolerability, and preliminary efficacy, of AMO-02 in adolescents and adults with Congenital and Childhood-onset DM1. Methods Sixteen subjects (aged 13 to 34) with Congenital and Childhood-onset DM1 received 12 weeks of single-blind fixed-dose oral treatment with either 400 mg (n=8) or 1000 mg (n=8) of AMO-02 (NCT02858908). Blood samples were obtained for pharmacokinetic assessment. Safety assessments, such as laboratory tests and ECGs, as well as efficacy assessments of syndromal, cognitive and muscular functioning, were obtained. Results AMO-02 plasma concentrations conformed to a two-compartment model with first-order absorption and elimination, and dose-dependent increases in exposure (area-under-the-curve, or AUC) were observed. AMO-02 was generally safe and well-tolerated. No early discontinuations due to adverse events nor dose adjustments of AMO-02 occurred. The majority of subjects manifested clinical improvement in their CNS and neuromuscular symptoms after 12 weeks of treatment compared to the placebo baseline, with a larger response noted at the 1000 mg/day dose level. AMO-02 exposure (cumulative AUC) was significantly correlated (p Conclusion AMO-02 has favorable pharmacokinetic and clinical risk/benefit profiles meriting further study as a potential treatment for Congenital and Childhood-onset DM1.