efgartigimod Indications

Clinical trial overview

gMG

Overview

gMG is a rare, chronic autoimmune disease in which pathogenic IgG autoantibodies disrupt neuromuscular signaling, leading to fluctuating and sometimes life‑threatening muscle weakness. Autoantibodies block or remove acetylcholine receptors and activate complement, damaging the neuromuscular junction. MG often begins with ocular symptoms such as ptosis and diplopia, and approximately 85% of patients progress to generalized MG (gMG), which can impair bulbar, limb, and respiratory function. Respiratory crises occur in 15–20% of patients. MG prevalence in the U.S. is estimated at approximately 20 per 100,000, and roughly 85% of gMG patients have detectable AChR antibodies.

efgartigimod has demonstrated consistent and robust clinical benefit across MG populations. Pivotal ADAPT data formed the basis for global approvals of VYVGART IV, and positive ADAPT‑SC results supported approval of the subcutaneous formulation. In 2025, we reported positive topline results from ADAPT‑SERON, our Phase 3 clinical trial in anti‑AChR antibody‑negative gMG, demonstrating a clear treatment effect and reinforcing the broad applicability of FcRn across MG subtypes. These data support our supplemental regulatory submission to expand VYVGART into the seronegative population, which was accepted for priority review with an expected PDUFA target action date of May 10, 2026. We also reported positive data from our ADAPT OCULUS clinical trial, which met its primary endpoint, showing that patients living with oMG and treated with VYVGART demonstrated statistically significant improvement from baseline in Myasthenia Impairment Index (MGII) Patient Reported Outcome (PRO) ocular scores at Week 4 compared to placebo. The results support our supplemental regulatory submissions to expand VYVGART into the ocular MG population. We also have ongoing clinical trials in pediatric gMG patients (ADAPT-JUNIOR) with efgartigimod IV and efgartigimod SC.

CIDP

Overview

CIDP is a chronic autoimmune disorder of peripheral nerves and nerve roots caused by an autoimmune-mediated destruction of the myelin sheath, or myelin producing cells, insulating the axon of the nerves and enabling speed of signal transduction. The cause of CIDP is unknown, but abnormalities in both cellular and humoral immunity have been shown. CIDP is a chronic and progressive disease: onset and progression occur over at least eight weeks in contrast with the more acute Guillain-Barré-syndrome. Demyelination and axonal damage in CIDP lead to loss of sensory and/or motor neuron function, which can lead to weakness, sensory loss, imbalance and/or pain. The U.S. prevalence is estimated at approximately 42,000 patients, of whom roughly 24,000 receive treatment. Most patients rely on IVIg as first‑line therapy, while glucocorticoids, plasma exchange, and other immunosuppressants are used less frequently given safety, tolerability, and access limitations.

In July 2023, the pivotal ADHERE clinical trial demonstrated that VYVGART SC significantly reduced the risk of relapse compared to placebo and provided evidence that pathogenic IgG autoantibodies play an important role in CIDP biology. Sixty‑seven percent of patients entering the open‑label Stage A improved clinically, and efgartigimod SC was well tolerated with a safety profile consistent with prior clinical trials. Nearly all eligible patients (99%) continued into the ADHERE‑Plus OLE. Based on these data, VYVGART SC received regulatory approvals in the U.S. in June 2024, in China in November 2024, and in Japan in December 2024, with regulatory review ongoing in additional jurisdictions, including the EU.

Primary ITP

Overview

Primary ITP is an acquired autoimmune bleeding disorder, characterized by a low platelet count (<100×109/L) in the absence of other causes associated with thrombocytopenia. In most patients, IgG autoantibodies directed against platelet receptors can be detected. They accelerate platelet clearance and destruction, inhibit platelet production, and impair platelet function, resulting in increased risk of bleeding and impaired quality of life. Primary ITP is differentiated from secondary ITP, which is associated with other illnesses, such as infections or autoimmune diseases, or which occurs after transfusion or taking other drugs, such as cancer drugs. Platelet deficiency, or thrombocytopenia, can cause bleeding in tissues, bruising and slow blood clotting after injury. Patients may suffer from depression and fatigue as well as side effects of existing therapies, impairing their quality of life. Current therapeutic approaches include non-specific immunosuppression (e.g., steroids and rituximab), inhibition of platelet clearance (e.g., splenectomy, IVIg, anti-D globulin, and spleen tyrosine kinase inhibitor fostamatinib13) or stimulation of platelet production (e.g., thrombopoietin receptor agonist TPO-RA). Splenectomy remains the only treatment that provides sustained remission off therapy for one year or longer for a high proportion of patients. ITP affects approximately 72,000 patients in the U.S.

In 2022, the Phase 3 ADVANCE (IV) clinical trial met its primary endpoint, demonstrating that a higher proportion of chronic ITP patients receiving efgartigimod achieved a sustained platelet count response compared to placebo. These results supported approval of efgartigimod for ITP in Japan. In 2023, the accompanying subcutaneous clinical trial, ADVANCE‑SC, did not meet its primary endpoint. To fulfill the requirement for two well-controlled trials needed for global registration, argenx is now conducting ADVANCE‑NEXT, a Phase 3, randomized, double‑blinded, placebo‑controlled trial evaluating efgartigimod IV in adults with primary ITP. ADVANCE-NEXT remains ongoing, with topline Phase 3 results expected in the fourth quarter of 2026.

AIM

Overview

AIM are a rare and heterogeneous group of autoimmune diseases that can affect muscle alone or multiple organ systems, including the skin, joints, lungs, gastrointestinal tract, and heart. These conditions are severe, disabling, and materially impact quality of life. Advances in understanding disease biology and the discovery of characteristic autoantibodies have led to clearer differentiation of AIM into clinically meaningful subtypes, including immune‑mediated necrotizing myopathy (IMNM), antisynthetase syndrome (ASyS), and dermatomyositis (DM). Each subtype presents with distinct autoantibody profiles and manifestations, though proximal muscle weakness remains a defining feature across AIM. Today, there are no FDA‑approved therapies for IMNM or ASyS, and treatment is largely dependent on steroids or broad immunosuppressants; IVIg was approved for DM in 2021.

argenx is advancing the registrational ALKIVIA clinical trial of efgartigimod SC for the treatment of AIM. ALKIVIA is a seamless Phase 2/3 clinical trial enrolling approximately 240 patients across IMNM, ASyS, and DM, with Total Improvement Score (TIS) as the primary endpoint and a broad set of functional and quality‑of‑life secondary measures. In November 2024, following achievement of statistical significance on the primary endpoint in the Phase 2 portion and consistent improvement across all six core components of the TIS, argenx announced a ‘GO’ decision to proceed with the Phase 3 portion in all three AIM subtypes. Safety and tolerability were consistent with the known profile of efgartigimod. ALKIVIA remains ongoing, with topline Phase 3 results expected in the third quarter of 2026.

SjD

Overview

SjD is a chronic, progressive autoimmune disease, characterized by lymphocytic infiltration and progressive destruction of exocrine glands. B-cells play a pivotal role in the development of the disease and this results amongst others in production of IgG autoantibodies, especially those which target SSA/Ro, SSB/La ribonuclear complexes. In addition to symptoms of dry eyes, dry mouth, chronic pain and fatigue, a substantial subset of patients suffer from extraglandular systemic disease. There are no FDA-approved treatments currently registered for the treatment of SjD.

argenx is advancing the registrational UNITY clinical trial of efgartigimod SC for the treatment of SjD. UNITY is a Phase 3, randomized, placebo‑controlled, double‑blind clinical trial assessing the safety and efficacy of efgartigimod SC in 480 patients with at least moderate systemic disease (ClinESSDAI ≥6) who are on stable background therapy and positive for anti‑SSA/Ro. After the 48‑week treatment period, eligible participants may roll over into an OLE. The primary endpoint is change from baseline in clinESSDAI, with key secondary endpoints focused on patient‑reported outcomes, ESSDAI, and STAR. UNITY remains ongoing, with topline Phase 3 results expected in the second half of 2027.