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Patients Receiving Efgartigimod Respond to COVID-19 Vaccination With IgG Antibodies

In an investigation on the effect of treatment with efgartigimod on humoral immune responses to COVID-19 vaccination, the immunization resulted in antigen-specific IgG responses in most patients.

Data from the ongoing ADAPT+ study (NCT03669588) of efgartigimod (Vyvgart; Argenx) in patients with generalized myasthenia gravis (gMG) who had also received a COVID-19 vaccination suggest that the vaccination resulted in humoral immune responses, specifically antigen-specific IgG.1 Preliminary data suggest that the efgartigimod treatment did not preclude effective humoral immune response with the COVID-19 vaccination, though the authors noted that the impact of concomitant immunosuppression requires additional study.

Fifteen patients received mRNA vaccines (2 doses), 2 received adenoviral vector vaccines (1 dose), and 1 patient received an unspecified vaccine. One patient did not receive concomitant efgartigimod and exhibited a 20-fold increase in spike protein receptor-binding domain (S-RBD) IgG titers (301.78 AU/mL). In the 17 patients vaccinated while receiving efgartigimod, mean S-RBD IgG levels increased from 72.29 AU/mL (range, <23.6 [lower limit of quantitation] to 331.08 AU/mL) to 756.09 AU/mL (range <23.6 to 3347 AU/mL).

Notably, 4 patients who also received concomitant immunosuppressive therapy did not demonstrate appreciable increases in S-RBD titers. One COVID-19 case occurred months post-vaccination in a patient not treated with efgartigimod.

James F. Howard, MD, Distinguished Professor of Neuromuscular Disease, and chief, Neuromuscular Disorders Section, University of North Carolina School of Medicine, and colleagues presented the data at the 2022 American Association of Neuromuscular & Electrodiagnostic Medicine Annual Meeting (AANEM), held September 21-24, in Nashville, Tennessee. Patients with gMG have increased adverse outcome risk from respiratory infections, including COVID-19. Howard et al noted that as such, some gMG therapies that increase the risk of infection may then attenuate immune responses to vaccines.

The ADAPT+ study in patients with gMG, efgartigimod (10 mg/kg IV) was administered in cycles of 4 weekly infusions, with subsequent cycles initiated based on clinical evaluation. S-RBD specific IgG responses were measured from available samples in 18 patients with gMG who received COVID-19 vaccination before October 2021.

Previous NeurologyLive® coverage on the ADAPT+ study with Howard and colleagues, reported that efgartigimod in patients with gMG suggest that the treatment is similarly effective for patients who have antiacetylcholine receptor antibody-seronegative (AChR-Ab–) generalized myasthenia gravis.2 Those data were also presented at the 2022 AANEM Annual Meeting as an abstract where the participants in the trial were those with AChR-Ab– gMG, who have limited treatment options, showing that efgartigimod, a human IgG1 antibody Fc fragment, has the potential to be a beneficial approach to the condition.

All told, those data showed that in one cycle of the ADAPT trial, 68.9% patients were treated with efgartigimod were deemed responders on the MG Activities of Daily Living (MG-ADL) scale, defined as a 2-or-more point improvement, compared with 63.2% of those on placebo, and 52.6% were responders on the Quantitative Myasthenia Gravis (QMG) scale, reporting 3-or-more point improvements, compared with 36.8% of those on placebo.2

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REFERENCES
1. Howard J, Sleasman J, Steeland S, et al. Response to Coronavirus 2019 Vaccination in Patients Receiving Efgartigimod. Presented at: AANEM 2022; September 21-24; Nashville, TN. Abstract 131.
2. Vu T, BrilV, Karam C, et al. Efficacy, Safety, and Tolerability of Efgartigimod in Anti-Acetylcholine Receptor Autoantibody Seronegative Patients with Generalized Myasthenia Gravtis: Integrated Interim Analysis of ADAPT/ADAPT+.Presented at: AANEM 2022; September 21-24; Nashville, TN. Abstract 105.