An immunomodulatory biotherapy, efgartigimod is a fragment of antibodies directed against the neonatal Fc or FcRn receptors. These receptors prevent the breakdown of immunoglobulins G (IgG), which include the autoantibodies produced in myasthenia gravis. By binding to FcRn, efgartigimod (or ARGX-113) reduces the recycling of IgG and therefore their circulating rate. Administered as an infusion on a weekly basis, efgartigimod is being investigated in a multicentre placebo-controlled phase III trial called ADAPT in 16 countries including France. This trial brings together 167 adult participants with myasthenia gravis with or without anti-acetylcholine receptor autoantibodies (anti-RACh).
Performances to be confirmed and detailed
The Dutch company argenx, which develops efgartigimod, announced in a press release on May 26, 2020 the results of the ADAPT test. According to this document:
- the drug candidate would have been well tolerated, with a safety profile comparable to that of placebo;
- the rate of participants with anti-RACh responders to treatment would have been significantly higher, compared to the score of activities of daily living (MG-ADL), in the group treated with efgartigimod (67.7%) compared to the placebo group (29 , 7%); that was the primary efficacy endpoint;
- 63.1% of anti-RACh + participants responded to efgartigimod with regard to the quantitative QMG score versus 14.1% in the placebo group;
- 0% of RACh + participants treated with efgartigimod achieved minimum symptom expression (MSE) versus 11.1% in the placebo group.
While the ADAPT trial is extended by an open-label extension (ADAPT +), argenx plans to file a marketing authorization application by the end of 2020. Ȧ note that four other anti-FcRn agents are in the pipeline myasthenia gravis trial: rozanolixizumab, nipocalimab, RVT-1401 and batoclimab. In addition, clinical trials in progress or in preparation are evaluating efgartigimod in other autoimmune diseases (primary immune thrombocytopenia, chronic demyelinating inflammatory polyneuropathy), intravenously or subcutaneously.
Access argenx press release 26/05/2020 « argenx announces positive topline phase 3 ADAPT trial results »
