First in Human SAD/MAD Safety and PK Study With Adult DMD Safety and PK Cohort

Parts A-C enroll healthy volunteers; only entry criteria for Part D are described below. Part D Inclusion Criteria: * Able and willing to provide written informed consent after the nature of the study has been explained and prior to the commencement of any study procedures. * Considered reliable and capable of adhering to the protocol and able and willing to attend the necessary visits to the study site according to the judgment of the PI or designee. * Male patients ≥18 to ≤ 40 years (inclusive at the time of informed consent), or considered an adult able to consent to participate in a clinical study in the jurisdiction in which the study is being conducted. * Non-smoker and must not have used any tobacco or cannabis products within 2 months prior to Screening. * Has a definitive diagnosis of DMD based on documented clinical findings and prior genetic testing with a confirmed mutation in the DMD gene. * BMI ≥ 18.0 kg/m2 and ≤ 32.0 kg/m2 and weight ≥ 50 kg at Screening. * Stable dose of systemic glucocorticosteroids, heart medications, and/or other supportive medications, vitamins and supplements according to the standard of care for DMD for 3 months prior to the Screening visit and for the duration of the study. Participants that are not receiving glucocorticosteroids are also eligible, but must refrain from initiating glucocorticosteroid treatment for the duration of the trial. * Agree to abstain from donating blood or blood products during the study and for up to 3 months after the administration of the IP. Part D Exclusion Criteria: * Underlying psychological condition or history of any mental illness that, in the opinion of the PI or designee, would make it unlikely for the participant to comply with the protocol or complete the study per protocol. * Presence of acute or chronic illness or history of chronic illness sufficient to invalidate the patient's participation in the study or make it unnecessarily hazardous in the judgment of the PI. * Any clinically significant medical, surgical, or psychiatric abnormality that, in the judgment of the Investigator, is likely to interfere with study compliance, the safe participation of the subject or the assessment of safety or efficacy. * Any surgical procedures (eg, stomach bypass) or medical condition that might affect absorption of medicines. * Has donated blood within 60 days of IP administration or donated plasma within 7 days of IP administration or experienced loss of blood ≥500 mL within 2 months of IP administration. * Fever (body temperature \>38°C) or symptomatic viral or bacterial infection within 2 weeks prior to Screening. * Poor pill swallowing ability as determined by PI. * Presence or history of severe allergic or anaphylactic reactions, or sensitivity to the IP or its constituents. * History of relevant atopy including any confirmed significant allergic reactions against any drug, or multiple drug allergies (non-active hay fever is acceptable). * History of malignancy, except for non-melanoma skin cancer excised more than 2 years prior to Screening and cervical intraepithelial neoplasia that has been successfully cured more than 5 years prior to Screening. * Abnormal ECG findings at Screening and or Day -1 that are considered by the PI or designee to be clinically significant. * QT value, measured at Screening visit, greater than 450 msecs (male) on 12-lead ECG, using Fridericia's formula (QTcF) for correction. * Pulse ≤ 45 or ≥ 100 beats per minute (bpm); systolic blood pressure ≤ 90 mmHg or ≥ 160 mmHg, or diastolic blood pressure ≤ 50 mmHg or \> 95 mmHg at Screening. * History or presence of a condition associated with significant immunosuppression. * History of life-threatening infection (eg, meningitis). * Infections requiring parenteral antibiotics within 6 months prior to Screening. * Positive test for hepatitis C antibody (HCV), hepatitis B surface antigen (HBsAg), human immunodeficiency virus (HIV) antibody. * Vaccination with a vaccine within 28 days prior to the first administration of IP. * Creatine kinase \> ULN or ALP, AST, bilirubin, and/or ALT \>1.5 × ULN at Screening. * Anticipated change to prescription medication, over the counter medications, vitamins, supplements, and/or herbal remedies during the course of the trial. * Anything that the PI or designee considers would jeopardize the safety of the participant, prevent complete participation in the study (including the possibility that the participant will not cooperate with the requirements of the protocol) or compromise interpretation of the study data. * An employee, consultant, and/or immediate family member (ie, first degree relative, spouse, adoptees, or legal dependents) of the site, Sponsor, or the CRO.