Efgartigimod efficacy and safety in refractory myasthenia gravis: UK’s first real-world experience

Background We report our experience of patients with generalised myasthenia gravis (gMG) treated with efgartigimod, an neonatal Fc receptor antagonist, under the Early Access to Medicine Scheme (EAMS) in the UK. Methods Data from all UK patients treated with efgartigimod under the EAMS July 2022 to July 2023 were collected retrospectively. Efgartigimod was administered as per the ADAPT protocol (consisting of a treatment cycle of four infusions at weekly intervals with further cycles given according to clinical need). Results 48 patients with acetylcholine receptor antibody-positive gMG were treated in 12 centres. Most (75%) were female and most had a disease duration of over 10 years. The average MG-Activities of Daily Living (ADL) score at baseline was 11.2. Most (72.9%) patients had undergone thymectomy. 77.0% were taking prednisolone at baseline. All patients had used non-steroidal immunosuppressant treatments, the average number tried was 2.6 (range 1–6). 51% had received rituximab. 54.2% of patients required regular intravenous immunoglobulin/plasma exchange. 75% of patients had a mean reduction in the MG-ADL of≥2 points in the first cycle and this remained stable throughout the study. The mean intracycle reduction in the MG-ADL score in the first, second, third and fourth cycles were −4.6 to –3.9, −3.4 and −4.2, respectively. Side effects were generally mild. No rescue treatments were required. At the end of the study, 96% of patients remained on efgartigimod. Conclusion Efgartigimod is a safe and effective treatment for patients with refractory, treatment-resistant gMG.