Post-hoc analyses from the ADAPT clinical study demonstrate aggregate sustained benefit of Efgartigimod in generalized myasthenia gravis.

OBJECTIVES

This post-hoc analysis evaluates the long-term efficacy of efgartigimod versus placebo in adult patients with generalized myasthenia gravis (gMG) with acetylcholine-receptor autoantibodies (AChR-Ab+), based on data from the ADAPT RCT and its open-label extension ADAPT+.

METHODS

Changes from baseline in Quantitative Myasthenia Gravis (QMG) and Myasthenia Gravis-Activities of Daily Living (MG-ADL) scores were assessed by treatment group over the ADAPT (up to 20 weeks) and ADAPT+ time horizon (extended to 64 weeks for efgartigimod group patients). Response to treatment was defined as 5-point reduction in QMG or 3-point reduction in MG-ADL vs. baseline values.

RESULTS

AChR-Ab+ patients treated with efgartigimod spent a substantially greater percentage of time in response in ADAPT based on at least a 5-point change in QMG compared to the placebo group (44 % versus 13 % respectively, p = 0.0034). Analyses based on a 3-point change in MG-ADL in ADAPT showed the percentage of time in response was nearly double for efgartigimod versus placebo (59 % versus 30 % respectively, p = 0.010). These trends were also maintained using different response definitions, as well as in patients with and without prior immune therapy exposure and by time from diagnosis (<7 years versus ≥7 years).

CONCLUSIONS

The clinical benefit of efgartigimod was sustained over repeat treatment cycles and maintained over the long term. Response to treatment was consistent regardless of response definition and was repeated in different patient subgroups. Overall, the results of this analysis indicate that efgartigimod is an effective therapeutic option, demonstrating a robust benefit among AChR-Ab+ patients with gMG.