Safety and Efficacy of Tideglusib in Congenital or Childhood Onset Myotonic Dystrophy

Inclusion Criteria

Subjects who do not enter this study directly from completing the AMO-02-MD-2-003 study (i.e. subjects who did not complete AMO-02-MD-2-003, subjects who completed AMO-02-MD-2-003 but did not directly rollover or subjects who are re-entering AMO-02-MD-2-004), will not be considered eligible for the study without meeting all of the criteria below:

• Subjects under study must be individuals with a diagnosis of Congenital or Childhood Onset DM1.
• Diagnosis must be genetically confirmed
• Subjects must be male or female aged ≥6 years to ≤45 years at Screening
• Subjects must have a Clinical Global Impression - Severity (CGI-S) score of 3 or greater at Screening (V-1)
• Written, voluntary informed consent must be obtained before any study related procedures are conducted. Where a parent or legally authorized representative (LAR) provides consent, there must also be assent from the subject (as required by local regulations)
• Subject's caregiver must be willing and able to support participation for duration of study
• Subject must be willing and able to comply with the required food intake restrictions as outlined per protocol

Subjects entering directly from completing the antecedent AMO-02-MD-2-003 study will not be considered eligible for the study without meeting all of the criteria below:

• Subjects who have completed the antecedent AMO-02-MD-2-003 study through V11
• Written, voluntary informed consent must be obtained before any study related procedures are conducted. Where a parent or LAR provides consent, there must also be assent from the subject (as required by local regulations)
• Subject's caregiver must be willing and able to support participation for duration of study
• Subject must be willing and able to comply with the required food intake restrictions as outlined per protocol

Key Exclusion Criteria

• Body mass index (BMI) less than 13.5 kg/m² or greater than 40 kg/m²
• New or change in medications/therapies within 4 weeks prior to Eligibility/Baseline Visit
• Use within 4 weeks prior to Eligibility/Baseline Visit of strong CYP3A4 inhibitors (eg.clarithromycin, telithromycin, ketoconazole, itraconazole, posaconazole, nefazodone, idinavir and ritonavir)
• Concurrent use of drugs metabolized by CYP3A4 with a narrow therapeutic window (e.g. warfarin and digitoxin)
• Current enrollment in a clinical trial of an investigational drug or enrollment in a clinical trial of an investigational drug in the last 6 months other than the AMO-02- MD-2-003 study
• Existing or historical medical conditions or complications (eg. neurological, cardiovascular, renal, hepatic, gastrointestinal, endocrine or respiratory disease) that may impact the interpretability of the study results
• Hypersensitivity to tideglusib or any components of its formulation including allergy to strawberry