A boy participating in the phase II Daylight study of Duchenne muscular dystrophy (DMD) “has passed away suddenly,” according to Pfizer Inc. The participant had received fordadistrogene movaparvovec, a mini-dystrophin gene therapy, in early 2023. The fatal serious adverse event was reported May 3 as a cardiac arrest, Pfizer told BioWorld. Pfizer, together with the independent external data monitoring committee, is reviewing the data to understand the potential cause, the company added.