argenx Reports Positive Phase 3 Data for VYVGART in Ocular Myasthenia Gravis

Netherlands-based argenx SE announced positive topline results from the Phase 3 ADAPT OCULUS trial evaluating VYVGART (efgartigimod alfa and hyaluronidase-qvfc), a neonatal Fc receptor (FcRn) blocker, in adults with ocular myasthenia gravis (oMG). The study met its primary endpoint (p=0.012), demonstrating a statistically significant improvement in patient-reported ocular symptoms compared to placebo. The readout is notable because no targeted therapy is currently approved anywhere in the world for oMG, and ADAPT OCULUS is the first registrational trial designed to address this population specifically — a fact that, if the data hold up under peer review, could redefine how the condition is managed.

Trial specifics

ADAPT OCULUS is a Phase 3, randomized, double-blind, placebo-controlled, parallel-group study that enrolled 141 adult patients classified as MGFA Class I — meaning their muscle weakness was confined to the ocular muscles — across sites in North America, Europe, and Asia-Pacific. Patients were eligible regardless of acetylcholine receptor antibody (AChR-Ab) serostatus, provided they had a baseline Myasthenia Gravis Impairment Index (MGII) patient-reported outcome (PRO) ocular score of at least 6, with at least two ocular items scoring 2 or higher. All participants were maintained on stable background therapy, which could include acetylcholinesterase inhibitors, corticosteroids, or nonsteroidal immunosuppressants.

In Part A of the trial, participants were randomized 1:1 to receive four once-weekly subcutaneous injections of efgartigimod PH20 SC or matching placebo, delivered via prefilled syringe, followed by a four-week observation period. The primary endpoint was the change from baseline in the MGII PRO ocular score at Week 4 (Day 29). MGII is a validated instrument for measuring MG disease severity, and its ocular subdomain specifically captures the two hallmark symptoms of oMG: diplopia (double vision) and ptosis (drooping eyelids). In the overall population, patients receiving VYVGART showed a mean improvement of 4.04 points on the MGII PRO ocular score, compared with 1.99 points for placebo — a treatment difference of approximately 2 points that reached statistical significance. The company stated that patients treated with VYVGART experienced a marked reduction in both diplopia and ptosis. No new safety signals emerged; the tolerability profile was consistent with prior VYVGART studies across generalized MG and chronic inflammatory demyelinating polyneuropathy (CIDP).

Part B of the trial is an open-label extension in which all participants receive two cycles of four once-weekly efgartigimod injections separated by a four-week interval, with additional cycles from Cycle 3 onward permitted at clinically determined intervals of at least one week after the prior cycle's last dose. The company did not disclose whether Part B has concluded.

argenx said the positive results support a planned Supplemental Biologics License Application (sBLA) submission to the US FDA to expand the VYVGART label into oMG, targeted by the end of Q3 2026. Full data are expected at an upcoming medical meeting, though the specific venue has not been disclosed. Luc Truyen, argenx's chief medical officer, said in a statement that "ocular MG has been historically under-studied and represents a significant unmet need in the MG community," adding that the results "bring us one step closer to our vision of delivering a targeted, transformative treatment option to as many MG patients as possible."

Research context

Efgartigimod alfa is a first-in-class human IgG1 antibody fragment engineered to bind FcRn with enhanced affinity. FcRn functions as a recycling receptor that rescues IgG from lysosomal degradation, thereby extending the half-life of circulating immunoglobulins. By blocking this interaction, efgartigimod accelerates the catabolism of endogenous IgG, including the pathogenic autoantibodies that drive neuromuscular junction dysfunction in MG. The molecule originated from academic research at the Vrije Universiteit Brussel and was developed by argenx, which was founded in 2008 as a spinout from that institution. The subcutaneous formulation used in ADAPT OCULUS incorporates Halozyme's ENHANZE recombinant hyaluronidase technology to facilitate subcutaneous delivery.

The rationale for FcRn blockade in MG rests on the disease's well-characterized humoral pathophysiology. In most patients, autoantibodies — predominantly directed against the AChR — impair signal transmission at the neuromuscular junction. While oMG is anatomically restricted to the extraocular muscles, it is generally considered part of the same antibody-mediated spectrum as generalized MG, making systemic IgG reduction a mechanistically coherent strategy. Approximately 80% of MG patients initially present with ocular symptoms, and up to 92% experience ocular involvement at some point during their disease course. In 15–25% of patients, weakness remains confined to the ocular muscles. Despite this prevalence, current management of oMG relies on symptomatic therapies such as pyridostigmine and broad immunosuppression with corticosteroids or steroid-sparing agents — none of which are specifically approved for the ocular form of the disease.

VYVGART is already approved for generalized MG in AChR-Ab-positive adults, having received US FDA approval for the intravenous formulation in December 2021 and for the subcutaneous formulation (VYVGART Hytrulo) in June 2023. The subcutaneous product subsequently gained approval for CIDP. VYVGART also holds approval for gMG in the EU and Japan. Efgartigimod has received Orphan Drug Designation and Fast Track Designation from the US FDA for MG, though it is unclear whether any specific designations have been granted for the oMG indication. The molecule remains unapproved globally for oMG.

The competitive landscape for FcRn inhibitors in MG is active, though no other program has disclosed a dedicated oMG registrational trial. Key competing assets include:

• UCB's rozanolixizumab, an anti-FcRn monoclonal antibody that has generated Phase 3 data in generalized MG through the MycarinG study. Rozanolixizumab received US FDA approval for gMG in 2023 under the brand name RYSTIGGO, making it the second FcRn inhibitor approved in this space. UCB has not publicly disclosed a dedicated oMG development program.
• Johnson & Johnson's nipocalimab, another anti-FcRn antibody, which is in Phase 3 development for generalized MG. Nipocalimab is also being studied in maternal-fetal indications where transplacental IgG transfer is pathogenic. No oMG-specific trial has been announced.

Beyond the FcRn class, the broader MG treatment landscape has expanded in recent years with the approval of complement inhibitors — including Alexion's ravulizumab (ULTOMIRIS) and UCB's zilucoplan (ZILBRYSQ) — for generalized MG. However, these agents are likewise approved only for generalized disease and have not been tested in dedicated oMG trials.

The absence of any approved targeted therapy for oMG, combined with the lack of competing registrational programs in this specific population, means argenx currently faces no direct competitor for the indication. If the ADAPT OCULUS data withstand scrutiny at a medical congress and during regulatory review, VYVGART could become the first targeted treatment available to oMG patients — a population that has historically been managed with therapies developed and approved for other forms of MG or for general immunosuppression. The planned sBLA submission by end of Q3 2026 will test whether the US FDA considers the observed 2-point treatment difference on the MGII PRO ocular score sufficient for a label expansion, a question that will likely hinge on the clinical meaningfulness of that margin and the totality of secondary endpoint and Part B data yet to be disclosed.

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