EDG-5506 is an investigational product intended to protect and improve function of dystrophic muscle fibers. This Phase 1 study of EDG-5506 will assess the safety, tolerability, and pharmacokinetics (PK) and of EDG-5506 in adult healthy volunteers and in adults with Becker muscular dystrophy (BMD).

Enrolled participants in this study will receive a single oral dose or multiple oral doses of EDG-5506 or a placebo. Blood and urine samples will be collected to measure how EDG-5506 is processed by the body and how the body responds when exposed to EDG-5506. Participants in the single ascending dose part of the study will remain in the clinic for 7 days with a 42-day follow-up period. Participants in the multiple ascending dose part of the study will remain in the clinic for 16 days with a 13-day follow-up period. Safety, tolerability, and pharmacokinetics of EDG-5506 will be assessed in healthy volunteers prior to enrolling participants with Becker muscular dystrophy.

Inclusion Criteria:

• For all potential participants (Healthy volunteers and BMD): Male or for HV: female. For all: adults aged 18 to 55 years at time of consent.
• For HVs: Good general health, with no significant medical history, no clinically significant abnormalities on physical exam
• For BMD: Diagnosis of BMD based on documentation of mutation(s) in the dystrophin gene and BMD phenotype
• For BMD: Ability to ambulate
• For all: Weight greater than or equal to 50 kg and BMI less than 33 kg/m2
• For HV: Females must be of non-childbearing potential.
• For all: Males with female partners must use a medically accepted contraceptive regimen from first dose through 90 days after the last dose
• For all: Non-smoker and must not have used any tobacco products within 3 months prior to the Screening visit.
• For all: Able and willing to attend the necessary visits at the study center.

Exclusion Criteria:

• For all: History of, or physical exam findings indicating clinically significant endocrine, neurological, gastrointestinal, cardiovascular, hematological, hepatic, immunological, renal, respiratory, or genitourinary abnormalities or diseases that, in the opinion of the Investigator, would render the subject being unsuitable for the study.
• For all: Unable to refrain from strenuous exercise for 3 days prior to check-in and during study.
• For all: Participation in any other investigational drug study within 30 days or 5 half-lives (whichever is longer) of dosing in the present study.

Healthy volunteers: Male and non-childbearing potential females. Male Becker muscular dystrophy (BMD) participants