Overview
Principal investigator
Eligibility criteria
Inclusion Criteria:
* Diagnosis of DM1 with trinucleotide repeat size \>100.
* Age of onset of DM1 muscle symptoms ≥12 years.
* Clinically apparent myotonia equivalent to hand opening time of at least 2 seconds in the opinion of the Investigator.
* Hand grip strength and ankle dorsiflexion strength.
* Able to complete 10-MWRT, stair ascend/descend (MAD cohorts only), and 5×STS at screening without the use of assistive devices such as canes, walkers, or orthoses.
Exclusion Criteria:
* History of major surgical procedure within 12 weeks prior to the start of investigative product administration or an expectation of a major surgical procedure (eg, implantation of cardiac defibrillator) during the study.
* History of anaphylaxis.
* Medical condition other than DM1 that would significantly impact ambulation or participation in functional assessments.
* Treatment with medications that can improve myotonia within a period of 5 half-lives of the medication prior to performing screening assessments.
* Electrocardiogram (ECG) with the corrected QT interval by Fridericia's Formula (QTcF) ≥450 milliseconds (ms) in men and QTcF ≥460 ms in women, PR ≥240 ms, left bundle-branch block, or a conduction defect, which is clinically significant in the opinion of the Investigator.
* Percent predicted forced vital capacity (FVC) \<50%.
* History of tibialis anterior biopsy within 3 months of Day 1 or planning to undergo tibialis anterior biopsies during study period for reasons unrelated to the study.
* Participant has a history of suicide attempt, suicidal behavior, or has any suicidal ideation within 6 months prior to Screening that meets criteria at a level of 4 or 5 of the Columbia Suicide Severity Rating Scale (C-SSRS) or who, in the opinion of the Investigator, is at significant risk to commit suicide.
* Use of glucagon-like peptide 1 (GLP-1) agonist medications including semaglutide, dulaglutide, liraglutide, exenatide, or tirzepatide within a period of 5 half-lives of the medication prior to performing screening assessments.
* Significant weight loss during study participation may impact weight-based dosing, performance on muscle function assessments, and pharmacodynamic (PD) biomarkers. Note: Other inclusion and exclusion criteria may apply.
* Diagnosis of DM1 with trinucleotide repeat size \>100.
* Age of onset of DM1 muscle symptoms ≥12 years.
* Clinically apparent myotonia equivalent to hand opening time of at least 2 seconds in the opinion of the Investigator.
* Hand grip strength and ankle dorsiflexion strength.
* Able to complete 10-MWRT, stair ascend/descend (MAD cohorts only), and 5×STS at screening without the use of assistive devices such as canes, walkers, or orthoses.
Exclusion Criteria:
* History of major surgical procedure within 12 weeks prior to the start of investigative product administration or an expectation of a major surgical procedure (eg, implantation of cardiac defibrillator) during the study.
* History of anaphylaxis.
* Medical condition other than DM1 that would significantly impact ambulation or participation in functional assessments.
* Treatment with medications that can improve myotonia within a period of 5 half-lives of the medication prior to performing screening assessments.
* Electrocardiogram (ECG) with the corrected QT interval by Fridericia's Formula (QTcF) ≥450 milliseconds (ms) in men and QTcF ≥460 ms in women, PR ≥240 ms, left bundle-branch block, or a conduction defect, which is clinically significant in the opinion of the Investigator.
* Percent predicted forced vital capacity (FVC) \<50%.
* History of tibialis anterior biopsy within 3 months of Day 1 or planning to undergo tibialis anterior biopsies during study period for reasons unrelated to the study.
* Participant has a history of suicide attempt, suicidal behavior, or has any suicidal ideation within 6 months prior to Screening that meets criteria at a level of 4 or 5 of the Columbia Suicide Severity Rating Scale (C-SSRS) or who, in the opinion of the Investigator, is at significant risk to commit suicide.
* Use of glucagon-like peptide 1 (GLP-1) agonist medications including semaglutide, dulaglutide, liraglutide, exenatide, or tirzepatide within a period of 5 half-lives of the medication prior to performing screening assessments.
* Significant weight loss during study participation may impact weight-based dosing, performance on muscle function assessments, and pharmacodynamic (PD) biomarkers. Note: Other inclusion and exclusion criteria may apply.
For Referring Providers
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