Clinical Experience With Efgartigimod For Treatment Of Acetylcholine Receptor Antibody Positive Generalized Myasthenia Gravis
Nakul Katyal1, Karen Halldorsdottir2, Neelam Goyal3, Raghav Govindarajan4, Srikanth Muppidi3, Ali Habib2
1Stanford School of Medicine, 2University of California, Irvine, 3Stanford University, 4HSHS St. Elizabeth Medical Group
Objective:
Describe experience with use of efgartigimod in clinical practice in the first year after FDA approval.
Background:
Efgartigimod is a first-in-class neonatal Fc receptor (FcRn) antagonist approved for treatment of acetylcholine receptor antibody-positive generalized myasthenia gravis (AChR+ gMG). In the pivotal trial, patients received an initial 4-infusion treatment cycle with subsequent treatment cycles occurring based on loss of treatment response or a minimum of 5 weeks from last infusion.
Design/Methods:
Retrospective chart review. Patients with AchR+ gMG who were treated with efgartigimod and for whom myasthenia gravis activities of daily living (MG-ADL) scores were available prior to as well as after completion of treatment cycle were included in the cohort. Patients from three major academic neuromuscular centers were included. Information regarding MG history, MG treatment(s) immediately prior to efgartigimod start, MG-ADL and other MG-specific outcome measures, laboratory data and adverse events were recorded.
Results:
Of 20 patients who received the first cycle of efgartigimod, 11 were male and 9 were female with mean age of 61.35 (+18.03) year. 14 patients (70%) had clinically meaningful improvement (> 2 points) in MG-ADL scores, whereas 3 each had no change and worsening respectively. Total IGG levels decreased by mean of 61% (± 17%) in the 8 patients for whom data was available.
To date, over 20 patients have received at least 1 cycle of efgartigimod and of these patients, 11 have received 2 or more cycles.
Conclusions:
Our experience suggests that at least two third of the patients with AChR+ gMG have clinically meaningful improvement in MG-ADL scores after first treatment cycle of efgartigimod. Clinical response to subsequent treatment cycles and new initiations will be discussed.