Study of AOC 1044 in Healthy Adult Volunteers and Participants with Duchenne Muscular Dystrophy (DMD) Mutations Amenable to Exon 44 Skipping

Part A:

Key Inclusion Criteria:

• Aged 18 to 55 years, inclusive, at the time of informed consent

• Body mass index (BMI) of 18.5 to 32.0 kg/m2

Key Exclusion Criteria:

• Clinically significant abnormalities in laboratory results, ECGs, or vitals

• Current or recent use of prescription or nonprescription drugs

• Positive drug/alcohol test at Screening or Day -1

• Elevated blood pressure (BP) >130/80 mmHg at Screening

• Participation in a clinical study in which an investigational product was receivedwithin 1 month of screening or 5 half-lives of the investigational product

• Blood or plasma donation within 16 weeks of planned AOC 1044 administration Note:Other protocol defined Inclusion/Exclusion criteria may apply

Part B:

Key Inclusion Criteria:

• Aged 7 to 27 years, inclusive, at the time of informed consent

• Clinical diagnosis of DMD or clear onset of DMD symptoms at or before the age of 6years

• Confirmation of DMD gene mutation amenable to exon 44 skipping

• Weight ≥ 23 kg

• Ambulatory or non-ambulatory

• Ambulatory participants: LVEF ≥50% and FVC≥50%

• Non-ambulatory participants: LVEF ≥45% and FVC≥40%

• PUL 2.0 entry item A ≥3

• If on corticosteroids, stable dose for 30 days before screening and throughout thestudy

Key Exclusion Criteria:

• Biceps brachii muscles unsuitable for biopsy

• Serum hemoglobin < lower limit of normal

• Uncontrolled hypertension or diabetes

• Prior treatment with any cell or gene therapy

• Prior treatment with another exon 44 skipping agent within 6 months prior toinformed consent

• Recently treated with an investigational drug

• History of multiple drug allergies