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$374 million in fourth quarter and $1.2 billion in full year global net product sales sBLA for VYVGART® Hytrulo for CIDP accepted for priority review by FDA with PDUFA target action date of June 21, 2024 On track to report data from six Phase 2 proof-of-concept trials by end of 2024 Management to host conference call today at 2:30 pm CET (8:30 am ET) February 29, 2024, 7:00 am CET 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 reported financial results for the full year 2023 and provided a fourth quarter business update. “argenx reached thousands of new patients and their families in 2023 by delivering on our commitment to make VYVGART available to the global MG community,” said Tim Van Hauwermeiren, Chief Executive Officer of argenx. “This expansion demonstrates that VYVGART has the potential to address the high unmet need for innovation in patients suffering from MG, and moves us closer to sustainability as we build an integrated immunology company. Clinically, we generated significant data through multiple study readouts, achieving key milestones for both the CIDP and MMN patient communities and importantly advancing our second molecule, empasiprubart. Looking forward to 2024, we will act with a continued sense of purpose to expand our patient reach. We will use the learnings and momentum from our gMG launch to strategically lay the groundwork for a potential CIDP approval, leveraging our current infrastructure and deep relationships in the neurology community to position VYVGART SC for success. CIDP patients have been waiting for innovation, and we are eager to translate the transformative ADHERE data into potential benefit for patients as quickly as possible.” FOURTH QUARTER 2023 AND RECENT BUSINESS UPDATE Reaching More Patients with VYVGART VYVGART® (efgartigimod alfa-fcab) is a first-in-class antibody fragment targeting the neonatal Fc receptor (FcRn), and is now approved in more than 30 countries globally for the treatment of generalized myasthenia gravis (gMG). VYVGART subcutaneous (SC) (efgartigimod alfa and hyaluronidase-qvfc) is approved in the U.S. (as VYVGART Hytrulo), Japan (as VYVDURA®) and Europe, making VYVGART the only gMG treatment available as both an IV and simple SC injection. argenx is planning to reach more patients commercially through its multi-dimensional expansion efforts, including patients earlier in the MG treatment paradigm and new patient populations through global regulatory approvals for MG and the expansion of use to treat additional autoimmune indications. Generated global net product revenues (inclusive of both VYVGART and VYVGART SC) of $374 million in the fourth quarter and $1.2 billion in the full year of 2023Medicines and Healthcare products Regulatory Agency (MHRA) approved VYVGART SC in the United Kingdom for the treatment of adult patients with gMG on February 6, 2024, with self-administrationMinistry of Health, Labour and Welfare (MHLW) approved VYVDURA in Japan for the treatment of adult patients with gMG, inclusive of seronegative patients, on January 18, 2024, with self-administrationDecisions on regulatory approvals of VYVGART for gMG expected in Switzerland, Australia, Saudi Arabia and South Korea by end of 2024Decision on approval of VYVGART SC for gMG in China through Zai Lab expected by end of 2024Decision on approval of VYVGART for primary immune thrombocytopenia (ITP) in Japan expected in first quarter of 2024Supplemental Biologics License Application (sBLA) for VYVGART Hytrulo accepted for priority review by FDA for chronic inflammatory demyelinating polyneuropathy (CIDP); Prescription Drug User Fee Act (PDUFA) target action date of June 21, 2024Regulatory submissions of VYVGART SC for CIDP in Japan, Europe, China and Canada expected in 2024Registrational studies to expand VYVGART label into broader MG populations, including in seronegative patients, expected to start in 2024Update on pre-filled syringe development expected in first half of 2024; ongoing clinical studies expected to support potential approval in gMG and CIDP in 2024 Advancing Current Pipeline argenx continues to demonstrate breadth and depth within its immunology pipeline and is advancing multiple pipeline-in-a-product candidates. With efgartigimod, argenx is solidifying its leadership in FcRn and is on track to be approved or in development in 15 autoimmune indications by 2025. Beyond efgartigimod, argenx is advancing its earlier stage pipeline programs, including empasiprubart (C2 inhibitor) with Phase 2 studies ongoing in multifocal motor neuropathy (MMN), delayed graft function (DGF) and dermatomyositis (DM). In addition, argenx is evaluating ARGX-119, a muscle-specific kinase (MuSK) agonist in both congenital myasthenic syndrome (CMS) and amyotrophic lateral sclerosis (ALS). Evaluation ongoing to determine path forward in BALLAD study evaluating efgartigimod in bullous pemphigoid (BP), with an update expected in 2024Topline data from Phase 2 RHO study evaluating efgartigimod in primary Sjogren’s syndrome expected in first half of 2024Topline data from Phase 2 ALPHA study evaluating efgartigimod in post-COVID-19 postural orthostatic tachycardia syndrome (PC-POTS) expected in first half of 2024Topline data from seamless Phase 2/3 ALKIVIA study evaluating efgartigimod across three myositis subsets (immune-mediated necrotizing myopathy (IMNM), anti-synthetase syndrome (ASyS), and DM) expected in second half of 2024Full Phase 2 topline data from ARDA study evaluating empasiprubart in MMN expected to be shared in 2024; cohort 2 is ongoing to determine dose response ahead of Phase 3 study startPhase 1 study of ARGX-119 ongoing in healthy volunteers; subsequent Phase 1b/2a trials planned to assess early signal detection in patients with CMS and ALS in 2024 Leveraging Repeatable Innovation Playbook to Drive Long-Term Pipeline Growth argenx continues to invest in its discovery engine, the Immunology Innovation Program (IIP), to drive long-term sustainable pipeline growth. Through the IIP, four new pipeline candidates have been nominated, including: ARGX-213 targeting FcRn and further solidifying argenx’s leadership in this new class of medicine; ARGX-121 and ARGX-220, which are first-in-class targets broadening argenx’s focus across the immune system; and ARGX-109, targeting IL-6, which plays an important role in inflammation. On track to file four investigational new drug (IND) applications by end of 2025Received $30M milestone from AbbVie for advancement of ABBV-151 (ARGX-115) to Phase 2 FOURTH QUARTER AND FULL YEAR 2023 FINANCIAL RESULTS argenx SE UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF PROFIT OR LOSS Three Months Ended December 31, Twelve Months Ended December 31, (in thousands of $ except for shares and EPS) 2023 2022 2023 2022Product net sales $374,351 $173,396 $1,190,783 $400,720Collaboration revenue 32,486 764 35,533 10,026Other operating income 11,003 7,956 42,278 34,520Total operating income $417,840 $182,116 $1,268,594 $445,267 Cost of sales $(39,477) $(12,786) $(117,835) $(29,431)Research and development expenses (306,373) (147,798) (859,492) (663,366)Selling, general and administrative expenses (208,826) (135,287) (711,905) (472,132)Loss from investment in joint venture (1,788) (677) (4,411) (677)Total operating expenses (556,464) (296,548) (1,693,643) (1,165,607) Operating loss $(138,624) $(114,432) $(425,049) $(720,341) Financial income $40,308 $13,925 $107,386 $27,665Financial expense (280) (990) (906) (3,906)Exchange gains/(losses) 37,418 60,259 14,073 (32,732) Loss for the period before taxes $(61,178) $(41,238) $(304,496) $(729,314)Income tax benefit / (expense) $(37,994) $2,625 $9,443 $19,720Loss for the period $(99,172) $(38,613) $(295,053) $(709,594)Loss for the year attributable to: Owners of the parent $(99,172) $(38,613) $(295,053) $(709,594)Weighted average number of shares outstanding 59,118,827 55,364,124 57,169,253 54,381,371Basis and diluted (loss) per share (in $) (1.68) (0.70) (5.16) (13.05)Net increase/(decrease) in cash, cash equivalents and current financial assets compared to year-end 2022 and 2021 $987,296 $(144,180)Cash and cash equivalents and current financial assets at the end of the period $3,179,844 $2,192,548 DETAILS OF THE FINANCIAL RESULTS Total operating income for the fourth quarter and full year in 2023 was $418 million and $1,269 million, respectively, compared to $182 million and $445 million for the same periods in 2022, and mainly consists of: Product net sales of VYVGART and VYVGART SC for the fourth quarter and full year in 2023, were $374 million and $1,191 million, respectively, compared to $173 million and $401 million for the same periods in 2022.Collaboration revenue for the fourth quarter and full year in 2023 was $32 million and $36 million, respectively, compared to $1 million and $10 million for the same periods in 2022. The increase is mainly related to the clinical development milestone argenx achieved with AbbVie following the dosing of the first patient in the Phase 2 trial for ABBV-151. Collaboration revenue for full year in 2023 also includes $1 million in royalty revenue from VYVGART sales in China.Other operating income for the fourth quarter and full year in 2023 was $11 million and $42 million, respectively, compared to $8 million and $35 million for the same periods in 2022. The other operating income for the fourth quarter and full year in 2023, primarily relates to research and development tax incentives and payroll tax rebates. Total operating expenses for the fourth quarter and full year in 2023 were $556 million and $1,694 million, respectively, compared to $297 million and $1,166 million for the same periods in 2022, and mainly consists of: Cost of sales for the fourth quarter and full year in 2023 was $39 million and $118 million, respectively, compared to $13 million and $29 million for the same periods in 2022. The cost of sales was recognized with respect to the sale of VYVGART and VYVGART SC.Research and development expenses for the fourth quarter and full year in 2023 were $306 million and $859 million, respectively, compared to $148 million and $663 million for the same periods in 2022. The research and development expenses mainly relate to external research and development expenses and personnel expenses incurred in the clinical development of efgartigimod in various indications and the expansion of other clinical and preclinical pipeline candidates. The research and development expenses for the fourth quarter and the full year in 2023, includes the amortization of the priority review voucher submitted with the sBLA filling for VYVGART Hytrulo for the treatment of CIDP, which resulted in an expense of $102 million.Selling, general and administrative expenses for the fourth quarter and full year in 2023 were $209 million and $712 million, respectively, compared to $135 million and $472 million for the same periods in 2022. The selling, general and administrative expenses mainly relate to professional and marketing fees linked to the commercialization of VYVGART and VYVGART SC, and personnel expenses. Financial income for the fourth quarter and full year in 2023 was $40 million and $107 million, respectively, compared to $14 million and $28 million for the same periods in 2022. The increase in financial income is mainly due to an increase in interest income which results from higher interest rates and a higher amount of current financial assets, cash and cash equivalents as a result of the financing round in July 2023. Exchange gains for the fourth quarter and full year in 2023 were $37 million and $14 million respectively, compared to $60 million of exchange gains and $33 million of exchange losses for the same periods in 2022. Exchange gains/losses are mainly attributable to unrealized exchange rate gains or losses on the cash, cash equivalents and current financial assets denominated in Euro. Income tax for the fourth quarter and full year in 2023 was $38 million of tax expense and $9 million of tax benefit, respectively, compared to $3 million and $20 million of tax benefit for the same periods in 2022. Tax expense for the fourth quarter in 2023, consists of $12 million of income tax benefit and $50 million of deferred tax expense, compared to $12 million of income tax expense and $15 million of deferred tax benefit for the comparable prior period. Net loss for the fourth quarter and full year in 2023, was $99 million and $295 million, respectively, compared to $39 million and $710 million over the prior year periods. On a per weighted average share basis, the net loss was $5.16 and $13.05 for the twelve months ended December 31, 2023 and 2022, respectively. Cash, cash equivalents and current financial assets totalled $3.2 billion as of December 31, 2023, compared to $2.2 billion as of December 31, 2022. The increase in cash and cash equivalents and current financial assets resulted primarily from the closing of a global offering of shares, including a U.S. offering, which resulted in the receipt of $1.2 billion in net proceeds in July 2023, partially offset by net cash flows used in operating activities. FINANCIAL GUIDANCE Based on its current operating plans, argenx expects its combined Research and development and Selling, general and administrative expenses in 2024 to be less than $2 billion. argenx expects to utilize up to $500 million of net cash in 2024 on these anticipated operating expenses as well as working capital and capital expenditures. EXPECTED 2024 FINANCIAL CALENDAR May 9, 2024: Q1 2024 financial results and business updateJuly 25, 2024: Q2 2024 financial results and business updateOctober 31, 2024: Q3 2024 financial results and business update CONFERENCE CALL DETAILS The full year 2023 financial results and fourth quarter business update will be discussed during a conference call and webcast presentation today at 2:30 pm CET/8:30 am ET. 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. Dial-in numbers: Please dial in 15 minutes prior to the live call. Belgium 32 800 50 201France 33 800 943355Netherlands 31 20 795 1090United Kingdom 44 800 358 0970United States 1 888 415 4250Japan 81 3 4578 9081Switzerland 41 43 210 11 32 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, globally in the U.S., Japan, Israel, the EU, the UK, China and Canada. 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. For further information, please contact: Media:Ben Petokbpetok@argenx.com Investors:Alexandra Roy (US)aroy@argenx.com Lynn Elton (EU)lelton@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 can be identified by the use of forward-looking terminology, including the terms “plans,” “aims,” “continues,” “anticipates,” “expects,” “will,” or “commitment” and include statements argenx makes concerning its utilization of its learnings and momentum from its gMG launch for a potential CIDP approval and to position VYVGART SC for success; its plans to expand its patient reach, including through its multidimensional expansion efforts aimed at including patients earlier in the MG treatment paradigm and pursuing global regulatory approvals for MG as well as additional autoimmune indications; our goal to translate the ADHERE data into potential benefit for patients; the advancement of, and anticipated clinical development, data readouts and regulatory milestones and plans, including: (1) expected decisions on regulatory approvals of VYVGART for gMG in Switzerland, Australia, Saudi Arabia and South Korea by end of 2024, (2) expected decisions on approval of VYVGART SC for gMG in China through Zai Lab by end of 2024, (3) expected decisions on approval of VYVGART for ITP in Japan in the first quarter of 2024, (4) expected regulatory submissions of VYVGART SC of CIDP in Japan, Europe, China and Canada in 2024, (5) the expansion of our VYVGART registrational studies into broader MG populations, including in seronegative patients, expected to start in 2024, (6) the update on pre-filled syringe development expected in the first half of 2024, (7) clinical studies expected to support potential approval in gMG and CIDP in 2024, (8) expected update on the path forward for BALLAD study in 2024, (9) expected topline data from Phase 2 RHO in the first half of 2024, (10) expected topline data from Phase 2 ALPHA study in the first half of 2024, (11) expected topline data from Phase 2/3 ALKIVIA in the second half of 2024, (12) the full Phase 2 topline data from ARDA study expected in 2024, (13) planned Phase 1b/2a clinical trials of ARGX-119 in 2024, (14) four IND applications expected to be filed by end of 2025, (15) expected data from six Phase 2 proof-of-concept trials by the end of 2024, and (16) the expected approval or development in 15 autoimmune indications by 2025; the potential of its continued investment in its IIP to drive long-term sustainable pipeline growth; its future financial and operating performance, including its anticipated operating expenses and utilization of net cash for 2024; and our goal of translating immunology breakthroughs into a world-class portfolio of novel antibody-based medicines. 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, expectations regarding the inherent uncertainties associated with development of novel drug therapies, preclinical and clinical trial and product development activities and regulatory approval requirements, the acceptance of our products and product candidates by our patients as safe, effective and cost-effective, and the impact of governmental laws and regulations on our business. 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.

Reported $1.2 billion in preliminary* full-year 2023 global net product sales Submitted sBLA to FDA for VYVGART® Hytrulo for CIDP with priority review voucher (PRV); if approved, launch expected mid-2024 Reported positive data from Phase 2 ARDA study establishing proof-of-concept for empasiprubart in MMN Data from six Phase 2 proof-of-concept trials expected by end of 2024 Nominated four new pipeline candidates with IND filings expected by end of 2025 January 8, 2024, 7:00 AM CET 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 reported preliminary financial results for the full-year 2023, including global net product sales (inclusive of both VYVGART® and VYVGART Hytrulo), and announced its strategic priorities for 2024. “In 2023, we reached more than 6,000 patients globally, making VYVGART available to gMG patients around the world,” said Tim Van Hauwermeiren, Chief Executive Officer of argenx. “We continued to invest in and demonstrate the sustainability of our business by successfully launching our subcutaneous VYVGART product, and are poised for continued expansion in gMG and beyond in 2024. argenx is delivering on its promise to transform how the world understands autoimmunity. It is with this commitment in mind that we submitted our sBLA for VYVGART Hytrulo in CIDP and, if approved, expect to launch in the U.S. in mid-2024. We will continue to be aggressive in advancing our pipeline this year and expect to report efgartigimod data from six Phase 2 studies in 2024, and to further develop empasiprubart in MMN. Through sustained investment in our IIP, we expect to see repeat value creation, and plan to submit four new INDs by the end of 2025.” “Two years ago, argenx’s key goal was to launch efgartigimod in the U.S. Today, we have built a formidable global commercial organization with product approvals in over 30 countries worldwide and a vibrant pipeline of promising new therapeutics to address immune-mediated diseases. We have forged important partnerships that support our mission to advance the human understanding of immunology to best benefit patients. argenx is well positioned for sustained growth throughout 2024 and well into the future.” 2024 Strategic Priorities argenx will focus on three strategic priorities in 2024 to drive sustainable long-term growth, including: Reach more patients with VYVGART by building upon its strong commercial foundation to address ongoing unmet patient need, broaden the MG opportunity, and expand into CIDPAdvance its extensive pipeline through new data readouts, creating multiple opportunities to demonstrate transformative clinical benefitLeverage its repeatable innovation engine, driving pipeline growth through its Immunology Innovation Program Reach More Patients with VYVGART VYVGART (efgartigimod alfa fcab) is a first-in-class antibody fragment targeting the neonatal Fc receptor (FcRn) and is now approved in more than 30 countries globally. VYVGART subcutaneous (SC) (efgartigimod alfa and hyaluronidase-qvfc) is approved in the U.S. (as VYVGART Hytrulo) and Europe, making VYVGART the only gMG treatment available as both an IV and simple SC injection. argenx is planning to reach more patients commercially in 2024 through its multi-dimensional expansion efforts. argenx will work to reach patients earlier in the MG treatment paradigm and improve the lives of new MG patient populations through additional global regulatory approvals, and the expansion of uses to treat additional autoimmune indications. Regulatory approval decisions of VYVGART for gMG expected in Switzerland, Australia, Saudi Arabia and South Korea by end of 2024Through strategic collaboration with Zai Lab, VYVGART to be included on China’s 2023 National Reimbursement Drug List (NRDL), starting in January 2024Decision on approval of VYVGART SC for gMG in Japan expected in first quarter of 2024 and in China through Zai Lab by end of 2024Decision on approval of VYVGART for primary immune thrombocytopenia (ITP) in Japan expected in first quarter of 2024Supplemental Biologics License Application (sBLA) submitted to FDA for VYVGART Hytrulo for CIDP with priority review voucher (PRV); if approved, launch expected mid-2024Regulatory submissions of VYVGART SC for CIDP in Japan, Europe, China and Canada expected in 2024Registrational studies to expand VYVGART label into broader MG populations, including in seronegative patients, to start in 2024Update on pre-filled syringe development expected in first half of 2024; ongoing studies to support potential approval in gMG and CIDP in 2024 Advance Current Pipeline through Upcoming Data Readouts argenx continues to demonstrate breadth and depth within its immunology pipeline and is advancing multiple pipeline-in-a-product candidates. With efgartigimod, argenx is solidifying its leadership in FcRn and is on track to be approved or in development in 15 autoimmune indications by 2025. Beyond efgartigimod, argenx is advancing its earlier stage pipeline programs, including empasiprubart (C2 inhibitor) with Phase 2 studies ongoing in multifocal motor neuropathy (MMN), delayed graft function and dermatomyositis (DM). In addition, ARGX-119, a muscle-specific kinase (MuSK) agonist, will initiate Phase 1b/2a studies in congenital myasthenic syndrome and amyotrophic lateral sclerosis in 2024. Today, argenx reported positive clinical data from the first cohort of the Phase 2 ARDA study of empasiprubart, establishing proof-of-concept in MMN. After confirming IVIg dependence, 27 patients were withdrawn from IVIg treatment and randomized 2:1 to either empasiprubart or placebo for 16 weeks. Patients were monitored for clinical deterioration that required IVIg retreatment, which was the main efficacy endpoint of the study. Empasiprubart demonstrated a 91% reduction in the need for IVIg rescue compared to placebo [HR: 0.09 95% CI (0.02; 0.044)]According to the Patient Global Impression of Change scale, 94% (17/18) of empasiprubart-treated patients rated their condition as improved since study start, including 55% (10/18) who were much or very much improved. Of placebo patients, 89% (8/9) worsened or had no change.Empasiprubart demonstrated improvement on all six efficacy measurements compared to baselineSafety and tolerability profile were consistent with Phase 1 resultsCohort 2 is ongoing to determine dose response ahead of a Phase 3 study start argenx is on track to report topline data from five additional proof-of-concept studies in 2024, including: Phase 2 RHO study evaluating efgartigimod in primary Sjogren’s syndrome expected in first half of 2024Phase 2 ALPHA study evaluating efgartigimod in post-COVID-19 postural orthostatic tachycardia syndrome (PC-POTS) expected in first half of 2024Seamless Phase 2/3 ALKIVIA study evaluating efgartigimod across three myositis subsets (immune-mediated necrotizing myopathy (IMNM), antisynthetase syndrome (ASyS), and DM) expected in the second half of 2024 Leverage Repeatable Innovation Playbook to Drive Long-Term Pipeline Growth argenx continues to invest in its discovery engine, the Immunology Innovation Program (IIP), to drive long-term sustainable pipeline growth. Through the IIP, four new pipeline candidates have been nominated, including: ARGX-213 targeting FcRn and further solidifying argenx’s leadership in this new class of medicine; ARGX-121 and ARGX-220, which are first-in-class targets broadening argenx’s focus across the immune system; and ARGX-109, targeting IL-6, which plays an important role in inflammation. Preclinical work is ongoing in each candidate and argenx is on track to file four investigational new drug (IND) applications by the end of 2025. Preliminary* Fourth Quarter and Full-Year 2023 Financial Results Today, argenx also announced preliminary* global net VYVGART revenues for the fourth quarter and full-year 2023 of approximately $374 million and $1.2 billion, respectively. As of December 31, 2023, argenx had approximately $3.2 billion in cash, cash equivalents and current financial assets*. Based on its current operating plans, argenx expects its combined R&D and SG&A expenses in 2024 to be less than $2 billion. The projected 2024 cash burn will be approximately $500 million. argenx expects its existing cash, cash equivalents and current financial assets, together with anticipated future product revenues, to fund the Company to profitability. * - The preliminary selected financial results are unaudited, subject to adjustment, and provided as an approximation in advance of the Company’s announcement of complete financial results in February 2024. 42nd Annual J.P. Morgan Healthcare Conference Presentation and Webcast Mr. Van Hauwermeiren will highlight these updates in a corporate presentation at the 42nd Annual J.P. Morgan Healthcare Conference today, Monday, January 8, 2024, at 9:00 a.m. PT. The live webcast of the presentation may be accessed under Investors on the argenx website. A replay will be available for 30 days following the presentation. Phase 2 ARDA Study Design The Phase 2 ARDA study is a randomized, double-blinded, placebo-controlled multicenter study to evaluate the safety and tolerability, efficacy, pharmacokinetics, pharmacodynamics, and immunogenicity of two dose regimens of empasiprubart in adults with multifocal motor neuropathy (MMN). The study consists of an IVIg dependency and monitoring period and two 16-week treatment cohorts of 24 MMN patients receiving empasiprubart or placebo in a 2x1 randomization. The dosing for Cohort 2 was established after a planned interim analysis of the first nine patients to complete the 16-week treatment period from Cohort 1. The primary endpoint is safety and tolerability. Additional endpoints include time to IVIg retreatment, biomarker analyses of C2 levels, and changes in measurements on key functional scores (modified medical research council (mMRC)-10 sum score, grip strength, MMN-RODS) as well as several patient-reported quality of life outcome measures (fatigue severity score (FSS), chronic acquired polyneuropathy patient-reported index (CAP-PRI), and values of the patient global impression change (PGIC) scale). About Multifocal Motor Neuropathy Multifocal motor neuropathy (MMN) is a rare, chronic autoimmune disease of the peripheral nervous system. The disease is characterized by slowly progressive, asymmetric muscle weakness mainly of the hands, forearms and lower legs. MMN is often associated with anti-GM1 IgM autoimmunity, leading to activation of the classical complement pathway, driving subsequent axon damage. High-dose IVIg is the only approved treatment for MMN and patients typically experience disease progression despite therapy, indicating an unmet need for efficacious and better tolerated therapeutic options. About Empasiprubart Empasiprubart (ARGX-117) is a first-in-class humanized sweeping antibody that binds specifically to C2 thereby blocking both the classical and lectin pathways of the complement cascade. By blocking upstream complement activity, empasiprubart has the potential to reduce tissue inflammation representing a broad pipeline opportunity across multiple severe autoimmune indications. In addition to multifocal motor neuropathy, argenx is evaluating empasiprubart in delayed graft function following kidney transplant and dermatomyositis. About VYVGART and VYVGART SC VYVGART 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 globally 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). VYVGART 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. It is marketed as VYVGART Hytrulo in the U.S. and VYVGART SC in Europe, and may be marketed under different proprietary names following approval in other regions. 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, globally in the U.S., Japan, Israel, the EU, the UK, China and Canada. 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. Media: Ben Petokbpetok@argenx.com Investors: Alexandra Roy (US)aroy@argenx.com Lynn Elton (EU)lelton@argenx.com Preliminary Financial Results The financial results presented in this press release are preliminary, estimated, and unaudited. They are subject to the completion and finalization of argenx’s financial and accounting closing procedures. They reflect management’s estimates based solely upon information available to management as of the date of this press release. Further information learned during that completion and finalization may alter the final results. In addition, the preliminary estimates should not be viewed as a substitute for full quarterly and annual financial statements prepared in accordance with IFRS. There is a possibility that argenx’s financial results for the quarter ended December 31, 2023, and full year financial results for 2023 could vary materially from these preliminary estimates. In addition to the completion of the financial closing procedures, factors that could cause actual results to differ from those described above are set forth below. Accordingly, you should not place undue reliance upon this preliminary information. Additional information regarding the Company’s fourth quarter 2023 financial results and full year financial results for 2023 will be available in the Company’s annual report and Form 20-F, which will be filed with the Netherlands Authority for the Financial Markets and U.S. Securities and Exchange Commission (the “SEC”), respectively. 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 “plans,” “aims,” “believes,” “continues,” “hope,” “estimates,” “preliminary,” “anticipates,” “expects,” “intends,” “may,” “will,” “should,” or “commitment” and include statements argenx makes concerning its preliminary financial results for the full year 2023; its expansion efforts, including reaching more patients with VYVGART within the MG treatment paradigm, through geographic expansion and into new autoimmune indications, expanding into CIDP, and the anticipated development of empasiprubart and ARGX-119; the anticipated timing of its launch of SC efgartigimod for CIDP in the U.S.; the initiation, timing, progress and results of its anticipated clinical development, data readouts and regulatory milestones and plans; its strategic priorities, including the timing and outcome of regulatory filings and regulatory approvals; its expectations of future profitability; the potential of its innovative clinical programs; and the nomination of new development candidates. 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 argenx’s ability to successfully execute its business and growth strategies, the inherent uncertainties associated with development of novel drug therapies, preclinical and clinical trial and product development activities and regulatory approval requirements, the acceptance of our products and product candidates by our patients as safe, effective and cost-effective, volatile market conditions, and the impact of governmental laws and regulations on our business. 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.

Company builds on deep structure-based drug design capabilities to add protein therapeutics to pipeline: BCX17725 for Netherton syndrome — entering clinic in 2H 2024Bifunctional fusion protein enabling simultaneous inhibition of multiple complement pathways to better address complex complement-mediated diseases — entering clinic in 2025 Oral C5 program for generalized myasthenia gravis — entering clinic in 2025Combination of avoralstat with SCS Microinjector® from Clearside enables direct delivery into the suprachoroidal space in the eye to treat patients with DME — entering clinic in 2025 RESEARCH TRIANGLE PARK, N.C., Nov. 03, 2023 (GLOBE NEWSWIRE) -- BioCryst Pharmaceuticals, Inc. (Nasdaq: BCRX) today announced updates from its drug discovery process and additional therapies from its pipeline that the company will highlight at a Research and Development (R&D) Day today at 1:00p ET at the company’s Discovery Center of Excellence in Birmingham, Alabama. A live webcast of the event will be available online in the investors section of the company website at www.biocryst.com. “The success we are achieving with ORLADEYO demonstrates that when we deliver a first-in-class or best-in-class medicine, we can change patients’ lives. The focus of our discovery efforts is to leverage our 30-plus years of experience to bring more first-in-class or best-in-class medicines to patients living with complement-mediated and other rare diseases. The team is excited to share our approach, and our expanded pipeline of new programs, at our R&D Day,” said Jon Stonehouse, president and chief executive officer of BioCryst. “We have significantly diversified our pipeline and we continue to be disciplined around decisions to invest further only when a program meets the high bar we have set of first-in-class or best-in-class. We believe the combination of ORLADEYO, our exciting pipeline and our financial strength, position us to continue to make a big difference in patients’ lives, and that leads to sustainable growth for years to come,” Stonehouse added. PROGRAM UPDATES AT R&D DAY BCX17725 — Fusion Protein KLK5 Inhibitor for treatment of Netherton syndrome Netherton syndrome is a rare, lifelong genetic disorder that often presents in neonates or infancy. The disease is caused by the deficiency of a natural inhibitor (SPINK5) of KLK5, a serine protease responsible for regulating skin shedding. Patients may have red, scaly and inflamed skin and susceptibility to recurrent immune reactions. Netherton syndrome can be life threatening, especially during infancy when patients are vulnerable to dehydration and recurrent infections. Currently, there is no approved treatment for Netherton syndrome. BCX17725 is a potent and selective investigational fusion protein KLK5 inhibitor designed to provide best-in-class, potentially disease-modifying treatment for people with Netherton syndrome. At the R&D Day, the company plans to showcase how it applied its structure-guided drug design expertise to create this fusion protein, and share nonclinical data showing distribution of the molecule to the epidermis following intraperitoneal (IP) administration. The company expects to begin clinical trials of BCX17725 in 2024. Avoralstat — Plasma kallikrein inhibitor combined with Clearside’s SCS Microinjector® for treatment of diabetic macular edema (DME) in patients with sub-optimal response to anti-VEGF therapy DME is the most common cause of vision loss in individuals with diabetes and at least one-third of patients have persistent DME despite anti-VEGF therapies, which are administered via monthly injection. Data have shown that elevated plasma kallikrein may be a cause of non-response to anti-VEGF therapy. Delivering avoralstat directly into the suprachoroidal space of the eye with the SCS Microinjector could allow avoralstat to inhibit plasma kallikrein at the sites of edema formation in DME disease, the retinal and choroidal vascular endothelium. Avoralstat has low solubility, which supports evaluation of a suspension depot formulation for ophthalmic injection. With low solubility, the drug could persist in the eye at the site of disease for a long duration, resulting in less frequent injections. At the R&D Day, the company plans to present nonclinical data showing high levels of avoralstat are maintained in the eye for at least 90 days following suprachoroidal injection. Avoralstat was previously studied in an oral formulation in a phase 3 trial in patients with HAE. In the HAE clinical trial program in 276 individuals, avoralstat was safe and well tolerated with an adverse event profile similar to placebo. The company believes that combining a potent, low-solubility kallikrein inhibitor that has a pre-existing systemic safety database with the only FDA-approved approach to access the suprachoroidal space provides the potential to deliver a best-in-class medicine for DME patients inadequately controlled with anti-VEGF therapy. The company expects to conduct formulation and nonclinical work in 2024 and begin clinical trials in 2025. Oral C5 Inhibitor — Treatment of generalized myasthenia gravis (and other complement-mediated diseases) Generalized myasthenia gravis (gMG) is a chronic autoimmune, neuromuscular disease that causes muscle weakness that worsens after periods of activity. It is caused when autoantibodies (anti-AChR) form that activate the complement system, causing the immune system to attack the neuromuscular junctions, or connections between muscles and nerves. BioCryst is developing a first-in-class oral C5 inhibitor that could be the first targeted oral therapy with competitive efficacy to currently approved injected and infused anti-C5 therapies, such as eculizumab and ravulizumab. A drug with this profile could enable gMG patients to switch from infused therapy and address their disease earlier in the treatment paradigm. At the R&D Day, the company plans to show data from the nonclinical program highlighting the potency, selectivity, oral bioavailability and pharmacokinetic parameters of its lead molecule candidates. The company expects to complete lead optimization in 2024 and begin clinical trials in 2025. Bifunctional complement inhibitor — simultaneously inhibiting multiple complement pathways to better address complex renal complement-mediated diseases like IgAN and lupus nephritis BioCryst is developing a bifunctional complement inhibitor anti-C2 monoclonal antibody that also inhibits the alternative pathway. This investigational candidate could be a first-in-class combined inhibitor of the classical, lectin and alternative pathways of the complement system to best treat complex renal complement-mediated diseases like progressive IgAN and lupus nephritis, which are influenced by multiple complement pathways. At the R&D Day, the company plans to share nonclinical data demonstrating the strong potency and ability of the company’s bifunctional monoclonal antibody to inhibit multiple pathways in the complement system. The company expects to select a lead molecule in 2024 and begin clinical trials in 2025. Oral C2 Inhibitor — classical and lectin pathway complement inhibitor to treat autoimmune hemolytic anemias, including cold agglutinin disease (CAD) and warm autoimmune hemolytic anemia (wAIHA) The limited approved options for treating diseases like CAD and wAIHA are injectable or infused. An oral C2 inhibitor from BioCryst would be first-in-class and allow patients to switch from infused therapy and address their disease earlier in the treatment paradigm. Inhibiting C2 could decrease red cell destruction (hemolysis) in autoimmune hemolytic anemias by blocking the classical and lectin pathways. At the R&D Day, the company plans to describe the data targets for potency, selectivity and bioavailability of its lead compounds. The company expects to select a lead molecule in 2025. BCX10013 — Once-daily, oral Factor D inhibitor for renal complement-mediated diseases BCX10013 is a potent and selective Factor D inhibitor that, if it achieves comparable or superior efficacy to twice-daily alternative pathway inhibitors in development, would offer a best-in-class profile as the first and only oral alternative pathway inhibitor with once-daily dosing. At the R&D Day, the company plans to present data from the recently completed 160 mg cohort of its multiple ascending dose healthy volunteer trial which highlights the strength and duration of alternative pathway suppression achieved at this dose level, supporting once-daily clinical dosing. The company expects to report data from its ongoing proof-of-concept trial in 2024. ORLADEYO® (berotralstat) — Pediatric formulation for the prevention of HAE attacks in patients 2 to <12 years of age ORLADEYO, the first oral, once-daily plasma kallikrein inhibitor, is approved in the United States and many global markets for people with HAE age 12 and older. The ongoing APeX-P clinical trial is assessing an oral granule formulation of ORLADEYO in pediatric HAE patients who are 2 to <12 years of age. Approximately 40 percent of HAE patients have their first attack by five years of age and there are no current targeted oral therapies available for prophylaxis in children <12 years old. The company expects to submit a U.S. supplemental new drug application for the pediatric use of ORLADEYO in 2025. 2024 R&D Investment Guidance The company’s focus on rigorous best-in-class or first-in-class investment criteria, and the lower investment cost of earlier stage programs, are expected to limit 2024 R&D spending to a total of between $230 million and $240 million across all programs. This represents an increase from projected 2023 R&D spending of $25 million to $35 million, and represents a decrease from R&D spending in 2022 of $13 million to $23 million. These numbers include non-cash stock compensation. At the R&D Day, the company will describe its disciplined approach to capital allocation. About BioCryst PharmaceuticalsBioCryst Pharmaceuticals is a global biotechnology company with a deep commitment to improving the lives of people living with complement-mediated and other rare diseases. BioCryst leverages its expertise in structure-guided drug design to develop first-in-class or best-in-class oral small-molecule and protein therapeutics to target difficult-to-treat diseases. BioCryst has commercialized ORLADEYO® (berotralstat), the first oral, once-daily plasma kallikrein inhibitor, and is advancing a pipeline of small-molecule and protein therapies. For more information, please visit www.biocryst.com or follow us on LinkedIn. Forward-Looking Statements This press release contains forward-looking statements, including statements regarding BioCryst’s plans and expectations for its pipeline development. These statements involve known and unknown risks, uncertainties and other factors which may cause BioCryst’s actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These statements reflect our current views with respect to future events and are based on assumptions and are subject to risks and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements. Some of the factors that could affect the forward-looking statements contained herein include: the ongoing COVID-19 pandemic, which could create challenges in all aspects of BioCryst’s business, including without limitation delays, stoppages, difficulties and increased expenses with respect to BioCryst’s and its partners’ development, regulatory processes and supply chains, negatively impact BioCryst’s ability to access the capital or credit markets to finance its operations, or have the effect of heightening many of the risks described below or in the documents BioCryst files periodically with the Securities and Exchange Commission; BioCryst’s ability to successfully progress its pipeline development plans as described herein; the results of BioCryst’s partnerships with third parties may not meet BioCryst’s current expectations; ongoing and future preclinical and clinical development of product candidates may take longer and be more expensive than expected and may not have positive results; BioCryst may not be able to enroll the required number of subjects in planned clinical trials of product candidates; BioCryst may not advance human clinical trials with product candidates as expected; the FDA or other applicable regulatory agency may require additional studies beyond the studies planned for products and product candidates, may not provide regulatory clearances which may result in delay of planned clinical trials, may impose certain restrictions, warnings, or other requirements on products and product candidates, may impose a clinical hold with respect to product candidates, or may withhold, delay or withdraw market approval for products and product candidates; product candidates, if approved, may not achieve market acceptance; BioCryst’s ability to successfully commercialize its products and product candidates, manage its growth and compete effectively; risks related to the international expansion of BioCryst’s business; and actual financial results may not be consistent with expectations, including that revenue, operating expenses and cash usage may not be within management's expected ranges. Please refer to the documents BioCryst files periodically with the Securities and Exchange Commission, specifically BioCryst’s most recent Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K, which identify important factors that could cause actual results to differ materially from those contained in BioCryst’s projections and forward-looking statements. BCRXW Contact:John Bluth+1 919 859 7910jbluth@biocryst.com