Efgartigimod was well-tolerated and efficacious for the treatment of patients with generalized myasthenia gravis, according to study findings published in Lancet Neurology.
This was a multicenter, randomized, placebo-controlled phase 3 trial (ClinicalTrials.gov Identifer: NCT03669588). Study researchers recruited patients (N=167) with generalized myasthenia gravis for the ADAPT trial at 56 centers in North America, Europe, and Japan from 2018 to 2019.
They randomly assigned patients in a 1:1 ratio to receive 26 weeks of 10 mg/kg efgartigimod (n=84) or placebo (n=83) infusions. For each cycle, patients received 4 infusions. Clinical response was defined by at least a 2-point improvement in Myasthenia Gravis Activities of Daily Living (MG-ADL) score sustained for at least 4 weeks.
The intervention and control cohorts consisted of 75% and 66% women, and had a mean age of 45.9 (standard deviation [SD], ±14.4) and 48.2 (SD, ±15.0) years, respectively. 82% and 87% were White, 40% and 37% were Myasthenia Gravis Foundation of America (MGFA) class II, 56% and 59% MGFA class III, and 70% and 43% had a previous thymectomy, respectively. Most patients were positive for acetylcholine receptor antibody (77%) and were on immunosuppressive treatment at baseline (86%).
During cycle 1, more patients receiving efgartigimod responded to treatment (68% vs 37%; odds ratio [OR], 3.70; 95% CI, 1.85-7.58; P <.0001). Response was more pronounced among patients who were acetylcholine receptor antibody-positive (68% vs 30%; OR, 4.95; 95% CI, 2.21-11.53; P <.0001).
At day 126, 48.7% of the treatment and 26.6% of the control cohorts maintained at least a 2-point improvement in MG-ADL scores (P =.0001).
The median time from day 28 to no clinically meaningful improvement was 35 (interquartile range [IQR], 18-71) days for the efgartigimod recipients and 8 (IQR, 1-57) days for the placebo group (P =.26).
Adverse events were reported by 77% of the efgartigimod and 84% of the placebo cohorts. The intervention cohort was associated with lower rates of serious adverse events (5% vs 8%, respectively) and infusion-related events (4% vs 10%, respectively) but higher infections (46% vs 37%, respectively). Most common events included headache, nasopharyngitis, nausea, diarrhea, upper respiratory tract infection, and urinary tract infection.
This study was likely limited by the definition of response (³2-point improvement in MG-ADL scores), as it remains unclear whether this change corresponds with a real-world clinical response.
These data indicated efgartigimod infusions were well-tolerated and effectively improved symptoms of generalized myasthenia gravis. Long-term responses are currently being assessed in an open-label extension trial.
Disclosure: Multiple authors declared affiliations with the pharmaceutical industry. Please refer to the original article for a full list of disclosures.
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