Introduction: C5 inhibitors and FcRn inhibitors are newer treatments for generalized myasthenia gravis (gMG). There is no current guidance or reports of their use in combination. FcRn inhibitors have potential to decrease efficacy of monoclonal antibody treatments. We present a case when the two therapies are used in combination.

We present a 49-year-old woman with anti-acetylcholine receptor antibody positive gMG who had failed multiple steroid-sparing immunosuppressants and still with inadequate benefit on mycophenolate mofetil and intravenous immunoglobulin (IVIG). She began eculizumab in 2020 with added benefit, eventually switching to ravulizumab in May of 2022 due to wearing off effects. Efgartigimod was added to her regimen the next month as an alternative to IVIG. Prior to this switch, she consistently scored 1 or 2 on the myasthenia gravis – activities of daily living (MG-ADL) scale with chewing being the primary complaint and diplopia second, which continued through 2022. Since 2023 she has scored an MG-ADL of 0 and achieved minimal symptom expression (MSE). Between 2023 and 2024 she expressed a preference for subcutaneous modalities over infusion and began taking subcutaneous efgartigimod and switched to zilucoplan from ravulizumab. There was no significant change in her clinical outcomes with switch to a small cyclic peptide instead of a monoclonal antibody complement inhibitor and she has continued this regimen through 2025. 

Retrospective single center study. 

A drop in MG-ADL 2021 from 2 to 0 in 2025 after starting with only C5 inhibitor therapy and eventually transitioning to C5 inhibitor and FcRn combination therapy without signs of adverse effects.