To evaluate changes in utilization of nonsteroidal immunosuppressive treatments (NSISTs) before and after efgartigimod initiation in patients with myasthenia gravis (MG).

While reduction in usage of oral glucocorticoids after efgartigimod initiation has been previously observed in the United States (US), evidence is limited regarding the impact on NSIST utilization.

In this retrospective cohort study, patients with MG who initiated and continued efgartigimod treatment for at least 1-year were identified from a US medical and pharmacy claims database (based on information licensed from IQVIA: Longitudinal Access and Adjudication Data [LAAD] for the period April 2016−January 2024, reflecting estimates of real-world activity [all rights reserved]). Patients who had any usage of mycophenolate mofetil (MMF) or azathioprine (AZA) during the 90-day period immediately prior to efgartigimod initiation (index date) were selected. Mean (SD) average daily dose (ADD) of MMF and AZA was evaluated at baseline (during the 90 days immediately prior to index) and at 12-months after efgartigimod initiation (Days 330-360 after index).

103 patients with MMF usage and 60 patients with AZA usage before index were included. Mean (SD) age was 61.7 (12.9) years and 39% (n=40/103) were female in the MMF cohort. Mean (SD) age was 56.1 (15.4) years and 48% (n=29/60) were female in the AZA cohort. Among the MMF cohort, mean ADD (SD) of MMF significantly dropped from 1629.4 (862.7) mg/day at baseline to 1301.6 (1166.6) mg/day after efgartigimod initiation (P<0.05). Among the AZA cohort, mean ADD (SD) of AZA significantly dropped from 131.1 (80.4) mg/day to 92.4 (81.5) mg/day after efgartigimod initiation (P<0.05).

Based on US claims, overall ADD for both MMF and AZA were significantly reduced in patients who continued efgartigimod treatment for ≥1-year.