(P-154) Real-world Adherence of Nusinersen for the Treatment of Spinal Muscular Atrophy (SMA) Using US Electronic Health Records

Background: Nusinersen, an antisense oligonucleotide approved for the treatment of spinal muscular atrophy (SMA) across all ages, is administered intrathecally at a dose of 12 mg. In the US label, the approved administration starts with 3 loading doses at 14-day intervals, and a 4th loading dose 30 days thereafter. A maintenance dose is then administered every 4 months. Limited evidence exists on real-world adherence to nusinersen.

Objectives: To study real-world adherence and treatment patterns of nusinersen using a large US electronic health records (EHRs) database.

Methods: Patients with SMA treated with nusinersen from December 23, 2016 to September 30, 2019 were identified via medication and diagnosis codes in the Optum® de-identified Electronic Health Record dataset of over 100 million patients. Identified patients had 6 months or more of continuous enrollment before first date of nusinersen. Number (mean, median) of administrations and distribution of inter-dose intervals were calculated. The percentage of doses on time was determined using grace periods of 7 days for loading doses and 30 days for maintenance doses.

Results: During the study period, 67 newly treated patients receiving nusinersen were identified with a mean age (range) of 22.1 years (1-57) and with a mean (standard deviation [SD]) follow-up time of 15.7 (8.4) months. The mean (SD) and median number of administrations among those with 13 months of follow-up (n=43) was 5.1 (1.4) and 6.0, respectively within the same follow-up period. The mean (SD) and median number of administrations at 23 months of follow-up (n=21) was 8.0 (1.2) and 8.0, respectively, within the same follow-up period. These results align with the expected number of doses based on the US label. The inter-dose intervals also aligned with the expected dosing schedule: median (Q1-Q3) days from the previous dose were 14 (14-15) for the second and third doses, 35 (35-38) for the fourth dose, and 126 (122-129) for the maintenance doses. Of the total doses administered during the study period, 91.2% were administered on time.

Conclusions: This study demonstrated that, in a real-world sample from a large US data source, the vast majority of patients received nusinersen according to the dosing schedule.

Study sponsored by Biogen