argenx Announces Positive Topline Phase 3 Data from ADAPT-SC Study Evaluating Subcutaneous Efgartigimod for Generalized Myasthenia Gravis - Study met primary endpoint, demonstrating noninferior total IgG reduction at day

argenx Announces Positive Topline Phase 3 Data

from ADAPT-SC Study Evaluating Subcutaneous Efgartigimod for Generalized Myasthenia Gravis

Regulated Information/Inside Information

Breda, the Netherlands - March 22, 2022

- argenx SE (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives of people suffering

from severe autoimmune diseases, today announced positive topline data from the Phase 3 ADAPT-SC study evaluating subcutaneous (SC) efgartigimod

(1000mg efgartigimod-PH20) for the treatment of generalized myasthenia gravis (gMG). SC efgartigimod achieved the primary endpoint of

total IgG reduction from baseline at day 29, demonstrating statistical non-inferiority to VYVGART (efgartigimod alfa-fcab)

intravenous (IV) formulation in gMG patients. Based on these results, argenx plans to submit a Biologics License Application (BLA) to

the U.S. Food and Drug Administration (FDA) by the end of 2022.

SC efgartigimod is co-formulated with recombinant

human hyaluronidase PH20 (rHuPH20), Halozyme's ENHANZE drug delivery technology. ENHANZE facilitates subcutaneous injection

delivery of biologics that are typically administered via infusion, providing additional treatment options to patients based on individual

"Every person living with gMG experiences

the disease in their own way, including how they manage symptoms," said 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 and

Principal Investigator for the ADAPT-SC trial. "For many years, patients lacked sufficient treatment options, let alone those that

were tailored to their unique needs. These data, along with the recent approval of the intravenous formulation, VYVGART, represent exciting

advancements in the management of this debilitating, unpredictable disease by offering patients and physicians the option to select treatment

based on individual needs and preferences."

"Our goal is to redefine and deliver targeted

treatment options for people living with gMG globally. By listening to the gMG community, we heard the importance of creating optionality

and flexibility for patients. The ADAPT-SC results mark another important step toward achieving this, and further support our vision of

delivering a broad array of treatment options for gMG," said Tim Van Hauwermeiren, Chief Executive Officer of argenx. "We're

excited about the potential to deliver two best-in-class options that provide flexibility around route of administration and dosing schedule,

and look forward to collaborating with the FDA to bring another innovative treatment option to people living with gMG."

Highlights of Topline ADAPT-SC Data

Detailed data from the ADAPT-SC trial will be

submitted for presentation at a future medical meeting.

Phase 3 ADAPT-SC Trial Design

The Phase 3 ADAPT-SC trial was a randomized, open-label,

parallel-group, multicenter trial evaluating the non-inferiority of the pharmacodynamic (PD) effect of SC efgartigimod (1000mg efgartigimod-PH20)

as compared with IV efgartigimod (10mg/kg) in patients with gMG. The pharmacodynamic effect as measured by percent change from baseline

in total IgG levels at day 29, one week after the last dose of IV or SC efgartigimod, served as the primary endpoint in the ADAPT-SC trial.

The correlation between total IgG reduction and clinical benefit in gMG was demonstrated in a Phase 2 and the Phase 3 ADAPT trial, which

served as the basis for approval of VYVGART in the U.S. and Japan. Safety, clinical efficacy, immunogenicity and pharmacokinetics (PK)

A total of 110 adult patients with gMG in North

America, Europe and Japan enrolled in the ADAPT-SC trial and were treated. Inclusion criteria of the trial were the same as the Phase

3 ADAPT trial of VYVGART; enrolled patients had a confirmed gMG diagnosis and an MG-ADL total score of at least 5 with greater than 50%

of the total score attributed to non-ocular symptoms, at screening and baseline. Patients were on a stable dose of at least one gMG treatment

prior to randomization, including acetylcholinesterase inhibitors, corticosteroids or nonsteroidal immunosuppressive drugs, and were required

to remain on that stable dose throughout the primary trial.

Patients were randomized in a 1:1 ratio to receive

SC efgartigimod or IV efgartigimod for one treatment cycle consisting of four doses at weekly intervals. The total study duration was

approximately 12 weeks, including seven weeks of follow-up after the treatment cycle.

Conference Call and Webcast

A webcast of the live call may be accessed on

the Investors section of the argenx website at argenx.com/investors. A replay of the webcast will be available on the argenx website for

approximately one year following the call.

Please dial in 15 minutes prior to the live

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.

Safety Information for VYVGART (efgartigimod alfa-fcab) intravenous (IV) formulation (U.S.

prescribing information)

What is VYVGART (efgartigimod

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

VYVGART may cause serious side effects, including:

Before taking VYVGART, tell your health care provider

about all of your medical conditions, including if you:

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

Please see the full Prescribing Information for

VYVGART and talk to your doctor.

MG is a rare and chronic autoimmune disease where

IgG antibodies disrupt communication between nerves and muscles, causing debilitating and potentially life-threatening muscle weakness.

More than 85% of people with MG progress to generalized MG (gMG) within 18 months, where muscles throughout the body may be affected,

resulting in extreme fatigue and difficulties with facial expression, speech, swallowing and mobility. In more life-threatening cases,

MG can affect the muscles responsible for breathing. Patients with confirmed AChR antibodies account for 80-90% of the total gMG population.

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, in both an intravenous and subcutaneous (SC) formulation. SC efgartigimod

is co-formulated with recombinant human hyaluronidase PH20 (rHuPH20), Halozyme's ENHANZE drug delivery technology.

(efgartigimod alfa-fcab) is a human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), resulting in the reduction of

circulating immunoglobulin G (IgG) autoantibodies. It is the first and only approved FcRn blocker. VYVGART is approved in the United States

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

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

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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," "estimates," "anticipates,"

"expects," "intends," "may," "will" or "should" and include statements argenx

makes concerning the expected benefits of subcutaneous (SC) efgartigimod (1000mg efgartigimod-PH20) for the treatment of generalized

myasthenia gravis (gMG) and the market acceptance thereof. By their nature, forward-looking statements involve risks and uncertainties