Efgartigimod was well tolerated and effective in treating patients with generalized myasthenia gravis, according to the results of the study published in Lancet Neurology.
This was a phase 3, multicenter, randomized, placebo-controlled study (ClinicalTrials.gov Identifer: NCT03669588). From 2018 to 2019, the study researchers recruited patients (N = 167) with generalized myasthenia gravis at 56 centers in North America, Europe, and Japan for the ADAPT study.
They randomly assigned patients at a 1: 1 ratio to receive 10 mg / kg efgarigimod (n = 84) or placebo (n = 83) infusions for 26 weeks. The patients received 4 infusions for each cycle. Clinical response was defined by at least a 2-point improvement in Myasthenia Gravis Activities of Daily Living (MG-ADL) score, which was sustained for at least 4 weeks.
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The intervention and control cohort 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. 82% and 87% were white, 40% and 37% were Myasthenia Gravis Foundation of America (MGFA) Class II, 56% and 59% were MGFA Class III, and 70% and 43% had a prior thymectomy. Most patients were positive for acetylcholine receptor antibodies (77%) and were on immunosuppressive treatment at baseline (86%).
During the first cycle, more patients receiving efgartigimod responded to treatment (68% vs. 37%; odds ratio [OR], 3.70; 95% CI 1.85-7.58; P <0.0001). The response was more pronounced in patients with antibody-positive acetylcholine receptors (68% vs. 30%; OR 4.95; 95% CI 2.21-11.53; P <0.0001).
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 = 0.0001).
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 = 0.26).
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% and 8%) and infusion-related events (4% and 10%) but higher rates of infection (46% and 37%, respectively). The most common events were headache, nasopharyngitis, nausea, diarrhea, upper respiratory tract infections, and urinary tract infections.
This study was likely limited by the definition of response (32-point improvement in MG-ADL score) as it remains unclear whether this change is consistent with real clinical response.
These data showed that efgartigimod infusions were well tolerated and were effective in improving symptoms of generalized myasthenia gravis. The long-term response is currently being investigated in an open-label extension study.
Disclosure: Several authors stated links to the pharmaceutical industry. For a full list of the details, see the original article.
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Howard JF, Bril V, Vu T, et al. Safety, efficacy, and tolerability of efgartigimod in patients with generalized myasthenia gravis (ADAPT): a multicenter, randomized, placebo-controlled phase 3 study. Lancet Neurol. 2021; 20 (7): 526-536. doi: 10.1016 / S1474-4422 (21) 00159-9
