Real-World Outcomes of Efgartigimod in Adult Myasthenia Gravis

Efgartigimod (Vyvgart) is used in the management of myasthenia gravis (MG), but real-world data outside controlled trials, particularly regarding flexible dosing intervals and concomitant medication use, remain limited. The objective of this preliminary, single-center, hypothesis-generating case series was to evaluate the clinical effectiveness of efgartigimod, characterize variability in treatment-free dosing intervals, and explore associations between dosing intervals and concomitant immunosuppressive medication use among adult patients with MG in routine clinical practice. This was a retrospective chart review of MG patients at a single academic neuromuscular center who were directly evaluated by the principal investigator. Demographics, treatment dates, dosing intervals, concomitant medications, and myasthenia gravis activities of daily living (MG-ADL) scores were collected. Fixed- and mixed-effects models were used to examine associations between efgartigimod use and changes in prednisone or other immunosuppressant dosing. Nine patients were included (mean age 64 ± 18.1 years, 55.6% male). The average time between cycles was 47 days (SD = 46.5, CI = 34.98-59.01), with wide variability across patients. The average baseline MG-ADL was 8.56 and decreased by 4.44 at 60 days (SD = 3.43), 4.71 at six months (SD = 3.64), and 5.29 at 12 months (SD = 5.06). Reductions were statistically significant at all time points (p = 0.008, 0.016, and 0.031, respectively). Baseline dosing of prednisone, pyridostigmine, and mycophenolate mofetil did not systematically affect cycle length, but higher azathioprine doses were consistently associated with longer subsequent infusion intervals. Given the small sample size and single-center design, these findings should be interpreted as preliminary observations and hypothesis-generating rather than definitive conclusions. Efgartigimod was associated with significant improvements in MG-ADLs in this cohort, supporting its effectiveness under flexible, patient-centered dosing schedules. Findings suggest that concomitant azathioprine dosing may be linked to longer infusion intervals, potentially reflecting more stable disease or clinician comfort with extended cycles, although this requires further investigation. Larger, prospective studies are needed to define optimal scheduling strategies, long-term durability, and the potential for reducing polypharmacy.