argenx to Present New Data from Generalized Myasthenia Gravis Program at 2022 American Academy of Neurology Annual Meeting

Presentations demonstrate leadership in FcRn, including an oral presentation of data from the ADAPT+ open label extension study evaluating long-term safety, tolerability and efficacy of VYVGART^® (efgartigimod alfa-fcab) in adult patients with generalized myasthenia gravis

Regulatory News:

argenx SE (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases, today announced that interim data will be presented from ADAPT+ at the American Academy of Neurology (AAN) Annual Meeting in Seattle, WA, April 2-7. ADAPT+ is the global Phase 3 open-label extension study evaluating long-term efficacy, safety and tolerability of VYVGART^® (efgartigimod alfa-fcab) in adult patients with generalized myasthenia gravis (gMG).

Additional presentations at AAN will include a review of baseline characteristics from the Company’s pre-approval access program for VYVGART, as well as data on the treatment burden of gMG from a cross-sectional study of 152 U.S. adults with a self-reported gMG diagnosis.

“We are thrilled that our ADAPT+ study has been selected for an oral presentation at this important neurology forum, and hope these exciting data will advance healthcare providers’ understanding of long-term therapeutic outcomes with VYVGART as they continue to manage their gMG patients,” said Tim Van Hauwermeiren, Chief Executive Officer of argenx. “We remain as committed as ever to the gMG community, and look toward to offering deeper insight into the patient experience so we may best address their unmet needs and seek to alleviate the burden of this complex, debilitating disease.”

AAN 2022 Presentations:

Long-term Safety, Tolerability, and Efficacy of Efgartigimod in Patients with Generalized Myasthenia Gravis: Interim Results of the ADAPT+ Study

Tuesday, April 5, 2022, at 4:06 PM PT

Session: S25: Autoimmune Neurology 2: Clinical Trials and Treatment; Presentation 004

Presenter: James F. Howard Jr., M.D., Professor of Neurology (Neuromuscular Disease), Medicine and Allied Health, Department of Neurology, The University of North Carolina at Chapel Hill School of Medicine

Baseline Characteristics and Demographics of Patients Enrolled in an Expanded Access Program for Efgartigimod in Adult Patients with Generalized Myasthenia Gravis

Saturday, April 2, 2022 from 5:30 PM – 6:30 PM PT

Session: P3: Autoimmune Neurology: Peripheral Nervous System and Muscle 1; Presentation 001, Neighborhood 1

Presenter: Deborah Gelinas, M.D., Executive Director, Neuromuscular Medical Affairs, argenx

Treatment Burden According to Patients with Generalized Myasthenia Gravis

Sunday, April 3, 2022 from 5:30 PM – 6:30 PM PT

Session: P6: Neuromuscular Disease: Myasthenia Gravis 1; Presentation 008, Neighborhood 13

Presenter: Tuan Vu, M.D., Professor of Neurology, University of South Florida

The meeting abstracts are available online and can be accessed through the AAN meeting website at AAN.com. To learn more about VYVGART, please visit AAN Booth #317 or VYVGART.com.

See the full Prescribing Information for VYVGART in the U.S., which includes the below Important Safety Information. For more information related to VYVGART in Japan, visit argenx.jp.

IMPORTANT SAFETY INFORMATION FOR VYVGART^® (efgartigimod alfa-fcab) intravenous (IV) formulation (U.S. PRESCRIBING INFORMATION)

What is VYVGART^® (efgartigimod alfa-fcab)?

VYVGART is a prescription medicine used to treat a condition called generalized myasthenia gravis, which causes muscles to tire and weaken easily throughout the body, in adults who are positive for antibodies directed toward a protein called acetylcholine receptor (anti-AChR antibody positive).

What is the most important information I should know about VYVGART?

VYVGART may cause serious side effects, including:

• Infection. VYVGART may increase the risk of infection. In a clinical study, the most common infections were urinary tract and respiratory tract infections. More patients on VYVGART vs placebo had below normal levels for white blood cell counts, lymphocyte counts, and neutrophil counts. The majority of infections and blood side effects were mild to moderate in severity. Your health care provider should check you for infections before starting treatment, during treatment, and after treatment with VYVGART. Tell your health care provider if you have any history of infections. Tell your health care provider right away if you have signs or symptoms of an infection during treatment with VYVGART such as fever, chills, frequent and/or painful urination, cough, pain and blockage of nasal passages/sinus, wheezing, shortness of breath, fatigue, sore throat, excess phlegm, nasal discharge, back pain, and/or chest pain.

• Undesirable immune reactions (hypersensitivity reactions). VYVGART can cause the immune system to have undesirable reactions such as rashes, swelling under the skin, and shortness of breath. In clinical studies, the reactions were mild or moderate and occurred within 1 hour to 3 weeks of administration, and the reactions did not lead to VYVGART discontinuation. Your health care provider should monitor you during and after treatment and discontinue VYVGART if needed. Tell your health care provider immediately about any undesirable reactions.

Before taking VYVGART, tell your health care provider about all of your medical conditions, including if you:

• Have a history of infection or you think you have an infection
• Have received or are scheduled to receive a vaccine (immunization). Discuss with your health care provider whether you need to receive age-appropriate immunizations before initiation of a new treatment cycle with VYVGART. The use of vaccines during VYVGART treatment has not been studied, and the safety with live or live-attenuated vaccines is unknown. Administration of live or live-attenuated vaccines is not recommended during treatment with VYVGART.
• Are pregnant or plan to become pregnant and are breastfeeding or plan to breastfeed.

Tell your health care provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

What are the common side effects of VYVGART?

The most common side effects of VYVGART are respiratory tract infection, headache, and urinary tract infection.

These are not all the possible side effects of VYVGART. Call your doctor for medical advice about side effects. You may report side effects to the US Food and Drug Administration at 1-800-FDA-1088.

Please see the full Prescribing Information for VYVGART and talk to your doctor.

About Efgartigimod

Efgartigimod is an antibody fragment designed to reduce pathogenic immunoglobulin G (IgG) antibodies by binding to the neonatal Fc receptor and blocking the IgG recycling process. Efgartigimod is being investigated in several autoimmune diseases known to be mediated by disease-causing IgG antibodies, including neuromuscular disorders, blood disorders, and skin blistering diseases. Efgartigimod is currently approved in the United States as VYVGART^® (efgartigimod alfa-fcab) for the treatment of adults with generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) antibody positive and in Japan for the treatment of adults with gMG who do not have sufficient response to steroids or non-steroidal immunosuppressive therapies (ISTs).

About Generalized Myasthenia Gravis

Generalized myasthenia gravis (gMG) is a rare and chronic autoimmune disease where immunoglobulin G (IgG) autoantibodies disrupt communication between nerves and muscles, causing debilitating and potentially life-threatening muscle weakness. Approximately 85% of people with MG progress to gMG within 24 months¹, where muscles throughout the body may be affected. Patients with confirmed AChR antibodies account for approximately 85% of the total gMG population¹.

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-and-only approved neonatal Fc receptor (FcRn) blocker in the U.S. and Japan. The Company is evaluating efgartigimod in multiple serious autoimmune diseases and advancing several earlier stage experimental medicines within its therapeutic franchises. For more information, visit www.argenx.com and follow us on LinkedIn, Twitter, and Instagram.

References

1. Behin et al. New Pathways and Therapeutics Targets in Autoimmune Myasthenia Gravis. J Neuromusc Dis 5. 2018. 265-277

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 can be identified by the use of forward-looking terminology, including the terms “believes,” “hope,” “estimates,” “anticipates,” “expects,” “intends,” “may,” “will,” or “should” and include statements argenx makes concerning the expected long-term safety, tolerability and efficacy of VYVGART® (efgartigimod alfa-fcab) in adult patients with generalized myasthenia gravis. 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. A further list and description of these risks, uncertainties and other risks 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 uncertainties, the reader is advised not to place any undue reliance on such forward-looking statements. These forward-looking statements speak only as of the date of publication of this document. 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.

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