P.134 Real-world outcomes of exon skipping therapy use in patients with Duchenne muscular dystrophy: Experience at a single, large tertiary care center

To assess outcomes among patients with Duchenne muscular dystrophy (DMD) receiving exon skipping therapy in real-world practice. This is a retrospective analysis of clinical data for patients with DMD who were amenable for exon 45, 51 and 53 skipping from Stanford Children's Hospital Medical Center. Among 109 DMD patients aged 2-21 years, 8% were amenable to exon 51 skipping, 5% to exon 53 skipping and 2% to exon 45 skipping. We had a total of 15 patients treated: Eight patients were on eteplirsen therapy (exon 51 skipping) for an average of 4 years with age at onset ranging from 4 to 17 years (mean 9.8 years). Six patients on golodirsen therapy (exon 53 skipping) for an average of 1.5 years with age of onset from 5 to 16 years (mean 11.5 years). One patient was on casimersen (exon 45 skipping) for 1 year started at age 10 years. Most patients were followed on every 6 months, with some cases ranging from 3-24 months. Most patients continued usual steroid regimen (14/15) with 10/14 on daily dose, 4/14 on weekend dose. All ambulatory patients (5/8 on exon 51 skipping, 2/6 on exon 53 skipping) showed progression in both floor to stand and 10m walk, except for 1 patient on golodirsen who remained stable over 1 year. Most patients advanced on the Brooke scale by 1 score over a 3-4-year time point (5/10), however some patients remained unchanged (4/10) while others advanced 2 points (1/10). Similarly with respiratory function, most patients remained stable (6/13) or even improved (4/13), however some continued to show decline (3/13). Exon skipping is hypothesized not to impact cardiac function, and therefore expected cardiac progression in line with the current natural history was seen in our patients. All patients continued treatment with no evidence of side effects associated with exon skipping therapy. This single center study adds to the real-world evidence of the use of exon skipping therapy. There are limitations to retrospective study review. Motor progression is still seen with some promising change in respiratory function. Medication was well tolerated and safe.