Health-Related Quality of Life Improvements Seen in Myasthenia Gravis With Efgartigimod

Francesco Saccà

Recently reported ancillary data from the phase 3 ADAPT study (NCT03669588) showed that treatment with efgartigimod (Vyvgart; Argenx) had a significant impact on health-related quality of life (HRQoL) in patients with myasthenia gravis, with positive effects seen as early as the first week of treatment in both cycles.

Of the 167 patients enrolled, 129 (77.2%) were anti-acetylcholine receptor (AChR) antibody positive. Participants were randomly assigned 1:1 to either efgartigimod or placebo for a 28-week treatment period, consisting of up to 3, 8-week treatment cycles (TCs). Between TCs was an intertreatment cycle (ITC) of at least 5 weeks, the duration of which was based on each patient’s loss of treatment effect response, indicated by predefined change in Myasthenia Gravis Activities of Daily Living (MG-ADL).

Published in the Journal of Neurology, the analysis included data from the first 2 TCs. Lead investigator Francesco Sacca, assistant professor of neurology, University Federico II Naples, and colleagues included patients with an MG-ADL score of at least 5 points, and were on at least 1 stable dose of gMG treatment prior to screening and throughout the study. HRQoL measures used included the Myasthenia Gravis-Quality of Life 15-item revised (MG-QoL15r), an MG-specific measure, the EuroQoL 5-Dimensions 5-Levels (EQ-5D-5L), and visual analog scale (VAS), a more generic measure used across disease states.

Comparing the 2 arms, significantly greater improvements in HRQoL scores were seen in those on efgartigimod, even among patients who had poor HRQoL at baseline. Relative to placebo, there was a greater reduction in MG-QOL15r scores for AChR-Ab+ participants on efgartigimod (P <.0001), with statistically significant differences maintained for up to 8 weeks in TC1 and TC2. Throughout the study, there was an observed trend in mean change in MG-QOL15r that was similar to that in total IgG level, by week.

Least square mean changes from baseline indicated statistically significant differences in EQ-5D-5L utility and VAS scores between the 2 groups. For each dimension of the EQ-5D-5L, those treated with efgartigimod showed improvement, whereas those on placebo did not. Over TC1 and TC2, the percentage increase in patients reporting no issues with mobility was 38% in the efgartigimod group and 7% on placebo. For self-care, the average percentage increase was 36% for efgartigimod-treated patients vs 1.5% of those on placebo.

In comparison, 30% of patients on efgartigimod reported increase in no problems with usual activities vs rates of 9.5% for placebo. For pain/discomfort, increase for efgartigimod was 19% vs 11% for placebo; and for anxiety/depression, efgartigimod was an increase of 13% vs a decrease of 1.5% for those on placebo.

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Scores on MG-QOL15r and EQ-5D-5L VAS represented the strongest correlation with utility scores in the efgartigimod group. Other observations included a positive correlation between MG-QOL15r and MG-ADL total scores over the first TC (week 1: P = .0157; weeks 2-10: P <.0001); significant negative correlations were shown between MG-QOL15r and both the EQ-5D-5L VAS scores (week 1, P = 0.0024; week 2, P = 0.0003; weeks 3–10, P < 0.0001) and EQ-5D-5L UK utility scores (weeks 1–10, P < 0.0001).

Efgartigimod was originally approved in December 2021 based on findings from ADAPT. In the original analysis, the agent was shown to be well-tolerated and efficacious, meeting the primary end point of improvement in MG-ADL scores relative to placebo (67.7% vs 29.7%; P <.0001). Additionally, 40.0% of efgartigimod-treated AChR-Ab+ patients achieved minimal or no symptoms compared with 11.1% treated with placebo.

A list of secondary end points that demonstrated significant differences in the efgartigimod arm for AChR-Ab+ patients compared with placebo include MG-ADL responders in the overall population, as well as both AChR-Ab+ and AChR– patients (P <.0001), and time on trial in clinically meaningful improvement, defined as an MG-ADL improvement of 2 points or greater (P = .0001). Additional significant differences from efgartigimod group for AChR-Ab+ patients compared with placebo were fast onset of response on MG-ADL score, defined as onset observed in first 2 weeks (P = .0004).^2,3

A sustained response was observed in 88.6% AChR-Ab+ patients who met the primary end point for at least 6 weeks, 56.8% for at least 8 weeks, and 34.1% for at least 12 weeks. Furthermore, 70.6% of AChR-Ab+ patients received a second treatment cycle, compared to only 25.6% of placebo patients.

REFERENCES
1. Sacca F, Barnett C, Vu T, et al. Efgartigimod improved health-related quality of life in generalized myasthenia gravis: results from a randomized, double-blind, placebo-controlled, phase 3 study (ADAPT). Journal of Neurol. Published online January 4, 2023. doi:10.1007/s00415-022-11517.
2. Howard JF, Bril V, Vu T, et al. Safety, efficacy, and tolerability of efgartigimod in patients with generalised myasthenia gravis (ADAPT): a multicentre, randomised, placebo-controlled, phase 3 trial. Lancet Neurol. 2021;20(7):526-536. doi:10.1016/S1474-4422(21)00159-9
3. Argenx announces positive topline results from phase 3 ADAPT trial of efgartigimod in patients with generalized myasthenia gravis. News release. Argenx. Published May 26, 2020. Accessed December 17, 2021. globenewswire.com/news-release/2020/05/26/2038308/0/en/argenx-Announces-Positive-Topline-Results-from-Phase-3-ADAPT-Trial-of-Efgartigimod-in-Patients-with-Generalized-Myasthenia-Gravis.html