Efgartigimod efficacy and safety in refractory Myasthenia Gravis - UK’s first real-world experience

Abstract

Background: We report our experience of patients with generalised MG (gMG) treated with Efgartigimod, an FcRN antagonist, under the Early Access to Medicine Scheme (EAMS) in the UK. Methods: Data from all UK patients treated with Efgartigimod under the EAMS June 22-July 23 were collected retrospectively. Efgartigimod was administered as per the ADAPT protocol (consisting of a treatment cycle of 4 infusions at weekly intervals with further cycles given according to clinical need). Results: 48 patients with AChR 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-ADL score at baseline was 11.2. Most (72.9%) patients had undergone thymectomy. 77.0% were taking prednisolone at baseline. All patients had utilized non-steroidal immunosuppressant treatments, the average number tried was 2.6 (range 1-6). 51% had received Rituximab. 54.2% of patients required regular IVIg/PLEX. 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 1st, 2nd, 3rd and 4th cycles were -4.6, -3.9, -3.4 and -4.2 respectively. Side effects were generally mild though one patient stopped treatment due to severe hypokalemia. 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.