Argenx to stop clinical development of efgartigimod for AAV

In decision, company cites results from trials in other autoimmune diseases

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Argenx has decided not to go ahead with its development plans for efgartigimod as a potential treatment for ANCA-associated vasculitis (AAV) after the therapy failed to show beneficial effects in late-stage clinical trials of two other autoimmune diseases.

Efgartigimod is approved in the U.S. in two formulations for treating adults with generalized myasthenia gravis, an autoimmune disease that causes muscle weakness. It’s marketed in an intravenous or into-the-vein formulation as Vyvgart, and as Vyvgart Hytrulo for its under-the-skin, or subcutaneous, formulation. The subcutaneous formulation also is approved for generalized myasthenia gravis in the European Union and Japan, but sold under different brand names. 

Argenx had planned the launch of a proof-of-concept clinical trial toward last year’s end to determine whether it was likely that efgartigimod would bring any clinical benefit for people with AAV. At that time, no further details were provided.

The decision to bring efgartigimod’s clinical program in AAV to an end was announced as part of an Argenx business update. According to the company, the decision was based on recent data coming out of Phase 3 trials testing the therapy’s subcutaneous formulation in people with other autoimmune diseases.

Specifically, Argenx stated that its “decision [was] made to discontinue planned development of efgartigimod in ANCA-associated vasculitis (AAV) following risk assessment of all ongoing studies based on learnings from [the] ADDRESS … and ADVANCE SC … studies.”

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In the Phase 3 ADVANCE-SC trial (NCT04687072), efgartigimod’s subcutaneous formulation failed to outperform a placebo at sustaining increased platelet counts in adults with primary immune thrombocytopenia. The autoimmune disease is marked by a deficiency in clot-forming platelets that leads to excessive bleeding.

That same formulation also was not superior to a placebo at eliminating symptoms of pemphigus, an autoimmune disease of the skin and mucous membranes, in adult patients taking part in the Phase 3 ADDRESS trial (NCT04598477).

Argenx had previously decided not to continue developing efgartigimod for pemphigus based on learnings from the ADDRESS clinical trial. As for the clinical program in primary immune thrombocytopenia — for which Vyvgart recently obtained approval in Japan — the company planned to further analyze the trial data of the subcutaneous formulation.

Like other autoimmune diseases, AAV occurs when the immune system produces self-reactive antibodies that mistakenly react to the body’s own cells. In AAV, these antibodies attack neutrophils, a type of immune cells, and prime them against small blood vessels, causing inflammation and damage.

Argenx’s efgartigimod works by blocking the action of the neonatal Fc receptor (FcRn), a protein that prevents certain antibodies from being destroyed, helping them stay longer in circulation. Blocking FcRn is expected to lower the number of self-reactive antibodies that cause autoimmune diseases such as AAV.

The company continues to test efgartigimod in clinical trials in a number of autoimmune diseases, such as primary Sjögren’s syndrome, and multifocal motor neuropathy and myositis.