Real-world phosphorodiamidate morpholino oligomer treatment patterns in Duchenne muscular dystrophy: a claims-based analysis

Aim: Phosphorodiamidate morpholino oligomers (PMOs) are exon-skipping therapies administered through once-weekly intravenous infusions used to treat Duchenne muscular dystrophy (DMD). This study assessed treatment patterns among patients with DMD receiving PMOs using administrative claims data while accounting for limitations in claims data for these therapies. Materials & methods: This study used Inovalon ® public and private closed claims data (1 June 2016–31 March 2024). Male patients with ≥1 claim for a PMO approved for DMD in the US (eteplirsen, casimersen, golodirsen and viltolarsen) were included. Index date was the first PMO claim. All available follow-up data were used to assess continuous PMO claims coverage, ≥60-day and ≥30-day gaps in PMO claims and PMO re-initiation after a gap. Adherence during 1 year after index was measured using proportion of days covered (PDC). Treatment patterns were also assessed in patients stratified by baseline algorithm-defined nonambulatory status (inferred from claims). Results: Among 397 patients included, median (IQR) follow-up time was 788 (484, 1109) days. Gaps in PMO claims coverage occurred in 190 (47.9%) and 254 (64.0%) patients using ≥60-day and ≥30-day gaps, respectively, among whom 110 (57.9%) and 176 (69.3%) had PMO re-initiation. Using ≥60-day and ≥30-day gap lengths, median (IQR) time to first gap in PMO claims was 25.5 (22.3, 32.9) months and 13.5 (10.2, 17.7) months, respectively and median (IQR) time to PMO re-initiation (not including gap time) was 4.4 (2.8, 8.7) months and 2.5 (1.7, 3.2) months. Median (IQR) PDC was 78.8% (38.8, 94.0) during 1 year after index. PMO treatment patterns were generally similar in patients stratified by algorithm-defined nonambulatory status. Conclusion: In an analysis of administrative claims data, adherence to PMO treatment for DMD was high. For patients with a gap in PMO claims, most subsequently re-initiated treatment, indicating lower discontinuation rates than previously reported.