Indicate by check mark whether the registrant files or will file annual
reports under cover of Form 20-F or Form 40-F.
Indicate by check mark if the registrant is submitting the Form 6-K
in paper as permitted by Regulation S-T Rule 101(b)(1): ¨
Indicate by check mark if the registrant is submitting the Form 6-K
in paper as permitted by Regulation S-T Rule 101(b)(7): ¨
Pursuant to the requirements of the Securities
Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.
Exhibit 99.1
argenx Presents New Efgartigimod Data Showing
Long-Term Sustained Patient Benefit in Myositis and Sjogren’s Disease at EULAR 2026
| · | ALKIVIA+ data in myositis indicate efgartigimod provides sustained, clinically meaningful improvements and consistent safety |
| · | RHO+ data in Sjogren’s disease indicate maintenance of response following switch to biweekly dosing |
| · | Cross-indication analysis of efgartigimod data across rheumatology studies underscores consistent safety profile in large patient
population |
June 3, 2026, 7:00 AM CEST
Amsterdam,
the Netherlands – argenx SE (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives
of people suffering from severe autoimmune diseases, today announced the presentation of new data evaluating VYVGART® (IV: efgartigimod
alfa-fcab and SC or Hytrulo: efgartigimod alfa and hyaluronidase-qvfc) across autoimmune rheumatic diseases, including myositis and Sjogren’s
disease, to be presented at the European Alliance of Associations for Rheumatology (EULAR) 2026 Congress from June 3-6, 2026, in London,
UK.
“Our presentations at EULAR
further support the rationale for targeting FcRn in autoimmune rheumatic diseases and underscore its potential to address significant
unmet patient need,” said Luc Truyen, M.D., Ph.D., Chief Medical Officer at argenx. “We are encouraged by the consistency
of the long-term data as well as data underscoring efgartigimod's favorable safety profile across multiple autoimmune rheumatic diseases.
We are looking forward to additional results evaluating efgartigimod in myositis later this year as well as in Sjogren’s disease
next year.”
Myositis and Sjogren’s disease are both
chronic, progressive autoimmune diseases that are generally more common in women than men. Myositis can cause serious and irreversible
damage to muscles and organs, leading to a loss of independence and a significant burden for patients. Sjogren’s disease can cause
dry eyes and mouth, chronic fatigue, and joint pain. It can also affect multiple organ systems and lead to nervous system complications.
Efgartigimod provides sustained functional improvement in patients
with myositis
ALKIVIA+ is an ongoing open-label extension study
that enrolled patients who completed the 24-week, double-blind, placebo-controlled Phase 2 ALKIVIA trial, including those who continued
efgartigimod treatment and those who transitioned from placebo to efgartigimod. Results presented at EULAR are an interim analysis through
Week 52.
A key metric in ALKIVIA+ is Total Improvement
Score (TIS). TIS is a composite index based on six core set measures, including muscle strength, physician and patient global assessments
of disease activity, physical function, enzyme levels, and extramuscular activity. Higher TIS values reflect greater overall clinical
improvement. Moderate and major improvement are defined as TIS ≥40 and ≥60, respectively.
Results showed:
| · | At 52 weeks, 37.5% of patients who had continuously received efgartigimod maintained their major TIS improvement
from week 24. 33.3% of patients switching from placebo to efgartigimod achieved a similar major TIS improvement. Rates of moderate TIS
improvement were also similar between the groups, at 75.0% and 66.7%, respectively. |
| · | Sustained mean TIS benefit: Patients receiving continuous efgartigimod maintained clinically meaningful
improvement through 52 weeks, with a mean TIS of 52.19. Patients who switched from placebo to efgartigimod achieved comparable improvement,
with a mean TIS of 49.62 at week 52. |
| · | The
safety profile was consistent over the course of the study, with no increase in adverse events with longer exposure. |
| | | |
| · | These
results further support the mechanistic relevance of FcRn blockade in myositis, providing further evidence that pathogenic autoantibodies
are the underlying driver of disease. |
“Patients with autoimmune
myositis face the serious challenge that their immune system attacks their own body, causing irreversible muscle loss, weakness, pain
and reduced quality of life, while the limited available treatments can carry significant side effects and be difficult to tolerate long
term,” said Hector Chinoy, M.D., Ph.D., presenting study author and Professor of Rheumatology and Neuromuscular Disease at The University
of Manchester. “Emerging results from the ALKIVIA+ study suggest that efgartigimod has the potential to deliver meaningful and sustained
clinical benefit for patients with myositis, with a favorable tolerability profile.”
Topline results from the Phase 3 ALKIVIA study
are expected in the third quarter of 2026.
Efgartigimod achieved maintenance of response in Sjogren’s
disease
RHO+, a 48-week open-label extension study, evaluated
patients with Sjogren's disease who continued to receive efgartigimod, and those who transitioned from placebo to efgartigimod after completing
the 24-week double-blind treatment period of the Phase 2 RHO study.
Response
to efgartigimod was assessed using the Composite of Relevant Endpoints for Sjogren’s Syndrome (CRESS), a composite endpoint designed
to capture overall treatment benefit across multiple clinical domains, including disease activity as measured by ClinESSDAI. Patients
in the efgartigimod arm were switched to biweekly dosing based on ClinESSDAI response.
Results showed:
| · | Patients in the efgartigimod arm switching to biweekly dosing experienced maintenance of response on clinical
measures. |
| · | Patients in the placebo arm switching to efgartigimod experienced improvements in ClinESSDAI and increased
CRESS response. |
| · | At week 72, median ClinESSDAI scores were low in both groups: 2.5 in the efgartigimod arm and 2.0 in patients
who transitioned from placebo to efgartigimod. Low disease activity is indicated by a ClinESSDAI score of <5. |
| · | Efgartigimod was well tolerated, with no new safety signals identified following long-term use in participants
with Sjogren’s disease. |
The Phase 3 UNITY trial is currently ongoing to
assess efficacy and safety of efgartigimod in patients with moderate to severe Sjogren’s disease. Topline results are expected in
the second half of 2027.
Efgartigimod safety profile reinforced across autoantibody-driven
autoimmune diseases
A cross-indication safety analysis of efgartigimod
spanning multiple global clinical studies, including autoimmune rheumatic diseases, indicated that efgartigimod is consistently well-tolerated
across diseases and administration methods.
| · | Data showed a consistent safety profile across 834 treated patients and more than 1,300 patient-years
of follow-up. Efgartigimod was well tolerated in participants with autoimmune rheumatic diseases (myositis, Sjogren's disease, and lupus
nephritis), consistent with findings from prior studies in other IgG-mediated autoimmune diseases and also consistent with what
has been observed in approved indications globally. |
| · | Adverse
events were predominantly mild-to-moderate, and no increased event rates were seen in studies with a longer treatment duration. |
Deepening understanding of the underlying biology
Additional argenx activities include: the presentation
of the Phase 2 eSScape study design, evaluating the potential of efgartigimod in Systemic Sclerosis (SSc); an FcRn symposium exploring
the role of autoantibodies in autoimmune rheumatic diseases and highlighting the potential of targeting FcRn; and the launch of a new
myositis disease education campaign.
argenx additional information on the data at
EULAR 2026 can be found here. Details for argenx presentations are as follows:
| Title |
Lead Author |
Presentation |
| Myositis |
| The Long-Term Safety and Efficacy of Efgartigimod PH20 SC in Adult Participants With Active Idiopathic Inflammatory Myopathy: Results From the Phase 2 Randomized ALKIVIA and Open-Label Extension ALKIVIA+ Trials |
Rohit Aggarwal |
Poster #POS0261
Friday, June 5
13:36 BST
|
| Sjogren’s Disease |
| Long-Term Efficacy and Safety of Efgartigimod in Sjogren’s Disease: Findings from the RHO+ Open-Label Extension Study |
Isabelle Peene |
Oral Presentation #130
Wednesday, June 3
17:30-17:40 BST |
| Systemic Sclerosis |
| Efgartigimod PH20 Subcutaneous in Adults With Systemic Sclerosis: Design of a Phase 2, Randomized, Double-Blinded, Placebo-Controlled, Parallel-Group Study (eSScape) |
Dinesh Khanna |
Poster #POS0326
Friday, June 5
16:30 BST
|
| Multiple Disease Areas |
| Safety Profile of Efgartigimod Across Multiple Global Clinical Trials in Immunoglobulin G-Mediated Autoimmune Diseases With Emerging Data in Idiopathic Inflammatory Myopathy, Sjogren’s Disease, and Lupus Nephritis |
Hector Chinoy |
Poster #POS1200
Saturday, June 6
10:15 BST |
About Efgartigimod and Efgartigimod SC
Efgartigimod (efgartigimod alfa fcab) is a human
IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), resulting in the reduction of circulating IgG autoantibodies. It
is the first approved FcRn blocker for the treatment of generalized myasthenia gravis (gMG) and chronic inflammatory demyelinating polyneuropathy
(CIDP) globally, and for primary immune thrombocytopenia (ITP) in Japan. Efgartigimod SC is a subcutaneous combination of efgartigimod
alfa and recombinant human hyaluronidase PH20 (rHuPH20), Halozyme’s ENHANZE® drug delivery technology to facilitate subcutaneous
injection delivery of biologics.
About Myositis
Myositis is an autoimmune rheumatic disease that
can be progressive and may lead to significant muscle and organ involvement, resulting in functional impairment and substantial burden
for patients. It is characterized by skeletal muscle weakness with possible extramuscular manifestations involving the skin, joints, lungs,
gastrointestinal tract, and heart. Major subtypes include immune-mediated necrotizing myopathy (IMNM), dermatomyositis (DM), polymyositis
(PM), antisynthetase (ASyS), and inclusion body myositis, with muscle involvement being a common manifestation across most subtypes.
About ALKIVIA and ALKIVIA+ Study Design
The ALKIVIA study is a randomized, double-blind,
placebo-controlled, multicenter, operationally seamless Phase 2/3 study of efgartigimod SC for the treatment of autoimmune myositis across
IMNM, DM and PM. The ALKIVIA study enrolled 240 patients in total and is being conducted in two phases, with an analysis of the Phase
2 portion of the clinical trial after the first 90 patients completed the study, followed by a Phase 3 portion if a signal is observed
in the Phase 2 portion. The primary endpoint is the mean total improvement score (TIS) at the end of the treatment period (24 weeks in
Phase 2 and 52 weeks in Phase 3) of all treated patients (IMNM, DM and PM) compared to placebo. Key secondary endpoints include response
rates at the end of treatment, time to response, and duration of response in TIS, as well as change from baseline in individual TIS
components. Other secondary endpoints include quality of life and other functional scores. ALKIVIA+ is a 28-week open-label extension
study that evaluated myositis patients who received continuous efgartigimod treatment and those who transitioned from placebo to efgartigimod
after completing the 24-week double-blind, placebo-controlled Phase 2 ALKIVIA study. The primary endpoint of ALKIVIA+ is long-term safety
and tolerability.
About Sjogren’s Disease
Sjogren’s disease is a chronic and progressive,
systemic, autoimmune rheumatic disease associated with elevated autoantibodies and characterized by immune-mediated dysfunction of exocrine
glands and extraglandular organ manifestations. Sjogren's disease can be severely debilitating and have a negative impact on patient quality
of life, with common symptoms reported as dry eyes and mouth, fatigue, and joint pain. Sjogren's disease predominantly impacts women with
a 9:1 female:male incidence ratio. Given the heterogeneous nature of the disease, the treatment journey can be challenging with long delays
and high rates of misdiagnosis. There are no FDA-approved treatments targeting the disease itself, leaving current treatments to focus
primarily on individual symptom management.
About RHO and RHO+ Study Design
The Phase 2 RHO study was a randomized, double-blinded,
placebo-controlled multicenter proof-of-concept study to evaluate the safety and efficacy of efgartigimod in adults with Sjogren’s
disease. In order to enter the study, patients needed to test positive for anti-Ro autoantibodies and maintain residual salivary flow.
Thirty-four patients were randomized 2:1 to receive either efgartigimod or placebo for up to 24 weeks. Multiple endpoints and biomarkers
were evaluated in the signal-finding study, including the primary endpoint of CRESS (Composite of Relevant Endpoints for Sjogren’s
Syndrome). Within CRESS there are five components, spanning: systemic disease activity as measured by the ESSDAI (EULAR Sjogren’s
Syndrome Activity Index), patient reported outcomes as measured by the ESSPRI (EULAR Sjogren’s Syndrome Patient Reported Index),
tear and salivary gland function, and serology. To be a CRESS responder, patients needed to demonstrate a clinically meaningful benefit
in at least 3 of the 5 composite items. Additional datapoints were gathered including the ClinESSDAI, STAR (Sjogren’s Tool for Assessing
Response), biomarker data, and the change in lymphocytic infiltrate levels through parotid biopsies.
RHO+
was a 48-week open-label extension study that evaluated the safety of efgartigimod in adult patients with Sjogren's disease who continued
to receive efgartigimod IV, and those who transitioned from placebo to efgartigimod IV after completing the 24-week double-blind treatment
period of the Phase 2 RHO study. The primary endpoint of RHO+ was incidence and severity of AEs and AESIs, incidence of SAEs, changes
in laboratory test results, vital signs, and ECG results.
About UNITY Study Design
UNITY is an ongoing Phase 3 randomized, double-blinded,
placebo-controlled multicenter study with open-label extension to evaluate the efficacy, safety, and tolerability of subcutaneously administered
efgartigimod PH20, in adult participants with moderate-to-severe primary Sjogren’s disease.
About argenx
argenx is a global immunology company committed
to improving the lives of people suffering from severe autoimmune diseases. Partnering with leading academic researchers through its
Immunology Innovation Program (IIP), argenx aims to translate immunology breakthroughs into a world-class portfolio of novel antibody-based
medicines. argenx developed and is commercializing the first approved neonatal Fc receptor (FcRn) blocker and is evaluating its broad
potential in multiple serious autoimmune diseases while advancing several earlier stage experimental medicines within its therapeutic
franchises. For more information, visit www.argenx.com and follow us on LinkedIn, Instagram, Facebook,
and YouTube.
For further information, please contact:
Media:
Kate Dion
kdion@argenx.com
Colin McBean
cmcbean@argenx.com
Investors:
Alexandra Roy
aroy@argenx.com
Forward-looking Statements
The contents of this announcement include statements
that are, or may be deemed to be, “forward-looking statements.” These forward-looking statements generally can be identified
by the use of forward-looking words, such as “aim”, “anticipate”, “aspire”, “believe”,
“can”, “continue”, “could”, “estimate”, “expect”, “entail”, “forecast”,
“future”, “goals”, “hope”, “intend”, “is designed to”, “likely”,
“may”, “might”, “objective”, “plan”, “possible”, “potential”,
“pursue”, “project”, “predict”, “seek”, “should”, “strategy”,
“target”, “will” and other words and terms of similar meaning and expression, including in connection with any
discussion of future operating or financial performance. By their nature, forward-looking statements involve risks and uncertainties and
readers are cautioned that any such forward-looking statements are not guarantees of future performance. argenx’s actual results
may differ materially from those predicted by the forward-looking statements as a result of various important factors, including but not
limited to, the results of argenx’s clinical trials; uncertainties associated with the development of novel drug therapies; preclinical
and clinical trial and product development risks and setbacks; interpretation of argenx’s clinical trial data by regulatory authorities
and argenx’s ability to obtain regulatory approval; the risk that early stage clinical trials may not be predictive of results in
later stage or large scale clinical trials; the occurrence of adverse safety events or participant dropouts; the acceptance of its products
and product candidates by its patients as safe, effective, and cost-effective; the impact of governmental laws and regulations, including
tariffs, export controls, sanctions and other regulations on its business; the impact of healthcare regulations, including rules on reimbursement
for argenx’s products; competition in drug discovery, development and commercialization efforts; its reliance on third-party suppliers,
service providers and manufacturers; and instability and conflicts in the regions in which the company has suppliers or markets for its
products. A further list and description of these and other risks, uncertainties, and factors that could cause actual results to differ
materially from those referred to in the forward-looking statements can be found in argenx’s U.S. Securities and Exchange Commission
(SEC) filings and reports, including in argenx’s most recent annual report on Form 20-F filed with the SEC as well as subsequent
filings and reports filed by argenx with the SEC. Given these risks and uncertainties, the reader is advised not to place undue reliance
on such forward-looking statements. These forward-looking statements speak only as of the date of publication of this press release. argenx
undertakes no obligation to publicly update or revise the information in this press release, including any forward-looking statements,
except as may be required by law.
