Efficacy and safety of anti-FcRN treatment in refractory MG-the UK experience of the Efgartigimod EAMS

<h3>Background</h3> 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. <h3>Methods</h3> Data from all UK patients treated with Efgartigmod under the EAMS (June 22-July 23) was collected retrospectively. Efgartigimod was administered as per the ADAPT protocol (4 infusions at weekly intervals with further cycles given according to clinical need). <h3>Results</h3> 49 patients with AchR antibody-positive gMG were treated in 12 centres. Most (76%) were female and most had a disease duration&gt;10 years. The average baseline MG-ADL score was 11.2 (SD 3.2). 73% had undergone thymectomy. 71.4% were taking prednisolone at baseline. All patients had utilized non-steroidal immunosuppressant treatments [4.3 treatments on average (range 1–7)] and 51% had received Rituximab. 57% required regular IVIg/PLEX and 38% had required rescue IVIg/PLEX in the year before starting Efgartigimod. 77% had a mean reduction in the MG-ADL of ≥2 points in the first cycle and this remained stable throughout the study. The mean reductions in the MG-ADL score in the 1st, 2nd, 3rd and 4th cycles were -4.5, -6.3, -6.9 and -7.8 respectively. Side effects were 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. <h3>Conclusion</h3> Efgartigimod is a safe and effective treatment for refractory, treatment resistant gMG.