Argenx Files for FDA Approval of Efgartigimod for Generalized MG

Argenx has filed an application to the U.S. Food and Drug Administration (FDA) requesting the approval of efgartigimod (ARGX-113) to treat generalized myasthenia gravis (gMG).

Similar approval requests are on track to be filed in Europe and Japan this year, Argenx stated in a recently released corporate update. A filing with Chinese regulatory authorities is also planned, likely come soon after the FDA’s decision is announced.

In preparation for efgartigimod’s possible approval and commercialization in the U.S., Argenx is engaging with key stakeholders, building a commercial inventory, and developing a patient services program, the update noted.

The company also announced the launch of a registrational bridging study, comparing the pharmacological properties of a new under-the-skin (subcutaneous) injection formulation of efgartigimod to its original intravenous (into the vein) formulation in 50 gMG patients. This study’s launch was based on feedback from the FDA, as well as on data from previous studies.

“We are excited to enter a new chapter for argenx as we look toward commercialization and achieving our mission of reaching patients with debilitating rare diseases. We’ve submitted a BLA [application] to the FDA for efgartigimod in gMG and expect to have global efgartigimod trials ongoing this year in six indications and two formulations,” Tim Van Hauwermeiren, CEO of Argenx, said in a press release.

“We hope to continue to demonstrate the broad opportunity of [efgartigimod] within autoimmune diseases in 2021 and beyond,” he added.

Argenx also announced it has reached an exclusive license agreement with Zai Lab for the development and future commercialization of efgartigimod in Greater China, covering the mainland, Hong Kong, Taiwan and Macau.

Under its term, Zai Lab will retain the therapy’s exclusive development and commercial rights in that country, while Argenx will be eligible for an upfront equity payment of $75 million and an additional $100 million in milestone and royalty payments.

“We believe that Zai Lab is the ideal partner for us ahead of our first potential approval of efgartigimod in generalized myasthenia gravis (gMG) in the U.S., and we are aligned in our mutual passion to bring potential innovative immunology therapies to patients in need,” Van Hauwermeiren said in a separate press release.

“Efgartigimod is being evaluated in a broad range of autoimmune diseases and we look forward to bringing this potentially first-in-class product to patients in Greater China,” added Samantha Du, founder, chairperson and CEO of Zai Lab.

Efgartigimod is an investigational antibody fragment that is designed to block the activity of the neonatal Fc receptor, a protein that normally prevents IgG antibodies — including the harmful self-reactive antibodies found in MG patients — from being destroyed.

By blocking this protein receptor, efgartigimod is expected to lower the levels of harmful autoantibodies in the bloodstream of MG patients and alleviate their symptoms.

Data from a Phase 1 trial (NCT03457649) in healthy volunteers showed the therapy had the potential to lower the levels of MG autoantibodies. Results of a Phase 2 trial (NCT02965573) in gMG patients demonstrated that efgartigimod worked to safely ease symptoms.

More recently, a Phase 3 trial called ADAPT (NCT03669588) showed that the therapy was able to rapidly lower disease severity in gMG patients, regardless of whether they had antibodies targeting the acetylcholine receptor (AChR) — the most common type of MG autoantibodies.

Findings from ADAPT also showed that, over the course of four weeks, treatment lowered total IgG and anti-AChR levels by more than 50% in different patient subgroups.

In addition to MG, efgartigimod is being tested to possibly treat autoimmune conditions that include pemphigus vulgaris, immune thrombocytopenia, and chronic inflammatory demyelinating polyneuropathy.