Efgartigimod alfa, an FcRn (neonatal fragment crystallisable receptor) inhibitor that reduces IgG (immunoglobulin G) levels, was recently introduced as a first-in-class alternative to immunoglobulins for treatment of myasthenia gravis. After approval of a new therapy, it is crucial that safety continues to be monitored via pharmacovigilance databases.

To describe the real-world safety profile of efgartigimod alfa and immunoglobulins focusing on infections.

FDA Adverse Event Reporting System (FAERS) data up to 31 December 2023 were accessed using DiAna R package including algorithmic removal of duplicates. Reports of infections involving efgartigimod alfa or immunoglobulins as suspects were identified within the myasthenic population. Descriptive and disproportionality analyses were performed for each infection-related reaction term.

For the overall myasthenia gravis population, 5643 reports were identified in the period 2022-2023. Among these, the total number of reports with efgartigimod alfa and immunoglobulins as suspected drugs were 1499 and 443, respectively. Infections accounted for 37% (n=557) of the reports for efgartigimod and 24% (n=107) for immunoglobulins. Events reported for efgartigimod alfa were more likely to be serious (92% vs. 70.65%) and to result in hospitalisation (52% vs. 23.72%) than for immunoglobulins. In the disproportionality analysis for the period 2022-23 only one signal emerged for immunoglobulins, while 12 signals were identified for efgartigimod alfa related to various types of infections including respiratory and viral infections.

This analysis identified a potential risk of infections in myasthenia gravis patients treated with efgartigimod alfa or immunoglobulins in clinical practice potentially based on different mechanism of actions. Real-world databases such as FAERS are key sources for safety monitoring, although findings may be influenced by factors such as the patient population, immunosuppressant comedications and time of reporting. Additional data sources must be combined with FAERS to provide a complete overview of the safety profile of efgartigimod alfa and immunoglobulins.