Argenx Plans FDA Submission of Efgartigimod by Year’s End

Argenx is planning to submit an application to the U.S. Food and Drug Administration (FDA) by the end of this year for its lead candidate, efgartigimod (ARGX-113), for the treatment of generalized myasthenia gravis (gMG), the company announced.

Assuming the biologics license application (BLA) is approved, Argenx expects to launch the medication — which works by decreasing the number of circulating autoimmune antibodies in the body — in the U.S. next year.

“We are focused on our planned 2021 U.S. commercial launch of efgartigimod to bring this therapy to patients as quickly as possible,” Tim Van Hauwermeiren, CEO of Argenx, said in a press release.

The Dutch pharmaceutical also is planning to submit a similar application next year to Japan’s Pharmaceuticals and Medical Devices Agency, requesting regulatory approval for efgartigimod in that country.

Myasthenia gravis is caused by the immune system erroneously attacking proteins essential for nerve-muscle cell communication. This process is driven by immunological proteins called antibodies – specifically, a type of antibody called immunoglobulin G (IgG).

Efgartigimod was designed to prevent the recycling of IgG antibodies, thereby promoting their destruction and lowering levels of these antibodies in the body. The therapy has been given orphan drug status in both the U.S. and Europe. That designation, given to medicines for rare disease, qualifies the drug’s sponsor for various development incentives.

Topline results were recently announced from the Phase 3 ADAPT clinical trial (NCT03669588), which evaluated the safety and effectiveness of efgartigimod in 167 adults with gMG. The trial enrolled participants both with and without antibodies against acetylcholine receptor (AChR), the most common type of antibody that drives MG.

The participants were given either intravenous (into-the-vein) efgartigimod or a placebo, in addition to their current standard treatments, for 26 weeks (about six months).

ADAPT’s main goal was to assess the percentage of AChR-positive patients responding to treatment. That was defined as participants showing at least a two-point improvement on their Myasthenia Gravis Activities of Daily Living (MG-ADL) score — which assesses MG symptom severity — for at least four consecutive weeks.

Argenx reported that this goal was met, with significantly more AChR-positive patients on efgartigimod experiencing such clinically meaningful improvement on their symptom severity scores (67.7%) compared with those on the placebo (29.7%).

Efgartigimod also helped more of these patients achieve minimal to no symptoms (40% vs. 11.1%). In addition, those given Efgartigimod spent significantly more time showing clinically meaningful MG-ADL improvements than participants given the placebo.

In the overall population, Efgartigimod also was superior to the placebo, regardless of the presence of anti-AChR antibodies. Among participants who were not positive for these antibodies, the response rates were consistent with those seen in anti-AChR-positive individuals; however, the responses to the placebo were greater.

The therapy was well tolerated, with the safety profiles of efgartigimod comparable to those of the placebo.

After completing ADAPT, most participants (90%) entered an open-label extension study called ADAPT-Plus (NCT03770403). All those enrolled will receive the active treatment for up to three years.

“We are proud of the progress we have made during the first half of 2020 to advance our immunology pipeline and validate our first-in-class FcRn antagonist, efgartigimod,” Van Hauwermeiren said.

“We announced positive topline results from the Phase 3 ADAPT trial, furthering our conviction that efgartigimod has the potential to significantly improve the standard of care for people with gMG as well as several other autoantibody-driven diseases,” Van Hauwermeiren added.

The data also supports ongoing programs of efgartigimod across several other autoimmune conditions, including immune thrombocytopenia, inflammatory demyelinating polyneuropathy, and pemphigus vulgaris. The company plans to announce a fifth clinical program of efgartigimod by year’s end.