Determine the Safety and Dose of EN001 in Patients With Duchenne Muscular Dystrophy(DMD)

Inclusion Criteria: 1. Those aged 2 to 18 years old 2. Male 3. Those who are diagnosed with DMD due to a mutation in the dystrophin gene identified by a genetic test 4. Phenotypic evidence of DMD * Clinical signs or symptoms (proximal weakness, waddling gait, Gowers maneuver) * Elevated serum creatine kinase level 5. Those who have been using systemic corticosteroids at a stable dose for 24 weeks prior to screening and are expected to maintain the constant dose throughout the study period 6. Those who agree to use effective contraceptive measures until the short-term follow-up period of the clinical trial. In addition, their partner must also use a medically acceptable method of contraception (ie, oral contraceptives for women) for the same period. 7. Those who are willing to agree with the ICF and whose parent or representative is willing to provide written consent for the subject's participation in the clinical trial Exclusion Criteria: 1. Those who have clinical signs or symptoms of cardiomyopathy, defined as LVEF \<50% on echocardiography at screening 2. If ventilatory support is required during the day or if invasive mechanical ventilation via tracheostomy is used (Non-invasive ventilation such as positive pressure ventilation is allowed at night) 3. If hepatitis B core antibody and hepatitis C antibody are positive 4. If there is a history of major surgery within 12 weeks or it is expected during the study period 5. Those who have been exposed to gene therapy or genome editing within 24 weeks from the screening 6. Those who have experience with stem cell therapy 7. Those who have been administered Translarna granules (Ataluren) within 24 weeks from the screening 8. Those who are receiving treatment (other than corticosteroids) that may affect muscle strength or function within 12 weeks prior to screening 9. If laboratory test values are abnormal at the time of screening * Hemoglobin \<10 g/dL * Serum albumin \<2.5 g/dL * Platelet count \<50,000/ml * Abnormal GGT or total bilirubin (\>laboratory's upper limit of normal) * Abnormal renal function (Serum creatinine \>1.5 Times laboratory's upper limit of normal)" 10. Those with significant neuromuscular or genetic diseases other than DMD 11. Those with significant heart, lung, liver, kidney, hematological, immunological, behavioral disease, or other clinically significant diseases including malignant tumors 12. Those who have a previous or current medical condition that may adversely affect the safety of the subject, make it difficult to complete treatment, or affect the evaluation of clinical trial results at the discretion of the investigator 13. Those who do not have the will or ability to comply with clinical trial procedures at the discretion of the investigator