upon joining the study, baseline measurements are taken to record current health status. these include vital signs such as blood pressure and heart rate, basic laboratory tests, an electrocardiogram (ecg) to check heart rhythm, and a physical examination.

the purpose of these assessments is to provide reference points for later comparison during the study.

the participant receives a solution for infusion called entr-601-45. the dose is 20 mg/kg, meaning 20 milligrams of medication for each kilogram of body weight.

the medication is administered through an intravenous infusion, which involves delivering the drug directly into a vein over a short period of time.

the participant receives a second solution for infusion called entr-601-44. the dose is 18 mg/kg, meaning 18 milligrams of medication for each kilogram of body weight.

this medication is also given by intravenous infusion, using a vein as the route of delivery.

at each scheduled visit, the study team checks for any new or worsening health problems, known as treatment‑emergent adverse events (teaes).

measurements include vital signs, repeat laboratory tests, another ecg, and a physical examination to track safety over time.

the participant performs simple functional tests to evaluate muscle strength and mobility. these tests include a 10‑meter walk/run, timed rise from floor, timed 4‑stair climb, stride velocity at the 95th percentile, the north star ambulatory assessment, and the performance of the upper limb version 2.0.

each test is done in a standard way so that changes can be compared to the baseline measurements.

blood samples are taken to measure the concentration of the study drugs in the plasma and to detect any anti‑drug or anti‑dystrophin antibodies, which are proteins that the body might produce against the medication.

the participant continues to receive the specified doses of entr-601-45 and entr-601-44 by intravenous infusion according to the study schedule for the duration of the long‑term extension period.

ongoing safety checks and efficacy assessments are performed throughout this time to gather long‑term data.