A Phase 3 Study to Evaluate the Safety and Efficacy of AOC 1044 (Also Referred to as Delpacibart Zotadirsen) in Participants With DMD With Gene Mutations Amenable to Exon 44 Skipping

This study is looking for boys with Duchenne Muscular Dystrophy (DMD) who meet certain requirements. They must be able to walk and have a clear diagnosis of DMD confirmed by genetic tests. Importantly, their genetic test results must show a specific type of mutation that the medicine is designed to target, known as 'exon 44 skipping'. Boys must be between 7 and 16 years old when they agree to take part, and they need to have been on a stable dose of steroid medication (including Vamorolone) for at least six months before starting the study.

There are also some reasons why someone might not be able to join. This includes boys who have previously had gene therapy or certain cell treatments. If they've had other similar types of medicine called 'oligonucleotides' in the last six months (not including COVID-19 vaccines), they also won't be able to join. Certain recent changes to other medications like growth hormone, testosterone, or givinostat might also prevent participation, as these need to be stable for a set period before the study starts. Regular blood tests and assessments will be done to ensure everyone is suitable and safe to participate.

If you decide to take part, you'll first have a 'screening period' of up to 44 days to check if you're suitable. After that, you'll be randomly assigned to one of two groups for about a year (54 weeks). One group will receive the new medicine, AOC 1044, and the other will receive a placebo (a dummy medicine that looks the same but contains no active drug). Neither you, your family, nor the study doctors will know which you are receiving during this time.

The medicine (or placebo) will be given through a drip into your arm at the study clinic once every six weeks, for a total of nine doses. Throughout this period, you'll have regular visits for check-ups, assessments of your muscle strength and movement, and safety tests like blood samples. After this first year, everyone who wants to can enter an 'open-label' period. This means everyone will then receive the actual AOC 1044 medicine for another year (54 weeks), again given every six weeks for nine more doses. The final dose will be at around week 102, followed by a final health check-up a few weeks later, and then a safety follow-up visit. The total study duration, including follow-up, will be around two years and two months.