September 25, 2025

Via EDGAR

U.S. Securities and Exchange Commission
Division of Corporation Finance
Office of Life Sciences
100 F Street, N.E.
Washington, D.C. 20549

Dear Ms. Baynes, Mr. Gordon, Ms. Hamill and Mr. Campbell,

argenx SE (“argenx” or the “Company”) is submitting this letter in response to comments from the staff (the “Staff”) of the Securities and Exchange Commission (the “Commission”) contained in its letter dated August 25, 2025, relating to the above referenced Annual Report on Form 20-F for the year ended December 31, 2024 filed with the Commission on March 20, 2025 (the “Form 20-F”).

For your convenience, we have reproduced the Staff’s comments preceding the Company’s responses below. All capitalized and uncapitalized (but defined) terms used and not defined herein shall have the meaning given to them in the Form 20-F.

Form 20-F for Fiscal Year Ended December 31, 2024
Item 4.B Business Overview

Intellectual Property, page 55

Response: The Company respectfully submits that the expiration of the NHANCE patents in 2027 or 2028 does not currently present a material risk to the Company. Materiality arises in this instance if these patents cover third-party activities and these third parties would be liable for infringement. Based on publicly available information on current clinical development timelines, the Company does not believe this to be the case.

In consideration of the Staff’s comment, the Company expects to include a clarification in its Annual Report on Form 20-F for the year ended December 31, 2025 substantially as set forth below.

Specifically, we are materially dependent on elements of our regulatory, patent and other proprietary protection, including certain of those related to our core platform technologies, described in Section 1.6.2 “Platform Technologies” below and our product candidates, as described in Section 1.6.3 “Our Internal Programs” below and Section 1.6.4 “Our Partnered Programs” below.

Response: The Company respectfully refers the Staff to the section titled “Platform Technologies” on page 56 of the Form 20-F, which includes disclosure on the patent portfolio used for the Company’s ABDEG^TM platform. As disclosed, for the Company’s ABDEG^TM platform, which is incorporated in efgartigimod, the Company has a broad patent portfolio with multiple patent families that cover, or are intended to cover, the composition of matter and/or uses of certain FcRn antagonists to achieve disease-modifying effects. The composition of matter and other relevant patents arising from the same patent family in the U.S. are set to expire in 2036 while in many other countries the base expiry date is 2034. The Company anticipates several more patient innovations to evolve during development for which it intends to seek additional patent protection with later expiration dates.

In consideration of the Staff’s comment, the Company expects to include a clarification in its Annual Report on Form 20-F for the year ended December 31, 2025 substantially as set forth below.

Our Internal Programs

efgartigimod

efgartigimod incorporates the ABDEG™ platform technology, for which we co-own the technology with the University of Texas Southwestern Medical Center and enjoy certain exclusive license rights. We have a broad patent portfolio with multiple patent families covering the composition of matter and uses of certain FcRn antagonists to achieve disease-modifying effects. The composition of matter and other relevant patents arising from the same patent family in the U.S. expire in 2036 whereas in many other countries the base expiry date is 2034. We anticipate several more patient innovations to evolve during development for which we intend to seek additional patent protection with later expiration dates.

ITEM 5.A. Operating and Financial Review and Prospects - Operating Results

Results of Operations - Product Net Sales, page 87

Response: The Company respectfully acknowledges the Staff’s comment and the requirements of (i) paragraph 114 of IFRS 15 regarding the disaggregation of revenue into categories, and (ii) paragraph 32 of IFRS 8 concerning the disclosure of revenue by product or group of similar products.

The Company’s principal source of revenue consists of product net sales of VYVGART (efgartigimod alpha). As defined in the Form 20-F, VYVGART should be read as references to VYVGART IV and/or VYVGART SC, including VYVGART HYTRULO in relation to the U.S. and China, VYVGART in relation to the EU and the UK and VYVDURA in relation to Japan.

VYVGART IV and VYVGART SC are two formulations of the same primary biologic active substance, efgartigimod alfa (referred to as VYVGART). VYVGART IV is administered intravenously, while VYVGART SC is delivered subcutaneously. Although the method of administration (‘‘MoA’’) differ, both formulations are designed to achieve the same therapeutic objective. The availability of both options provides flexibility and interchangeability in treatment administration, allowing physicians to tailor therapy based on individual patient needs and preferences. The Company submits that this supports the conclusion that the products are similar for disclosure purposes. In reaching this view, the Company has considered the similarities in production and distribution processes, customer base, applicable regulatory frameworks across jurisdictions, and the underlying economic characteristics of the products, notwithstanding an alternative method of administration.

As part of the Company’s periodic internal controls over financial reporting, the Company assesses whether the level of revenue disaggregation is appropriate and sufficient pursuant to the IFRS requirements mentioned above. As disclosed in the Form 20-F, the Company disaggregates total revenues by jurisdiction/countries to comply with the requirements of IFRS 8.33, which requires disclosure of separate revenues from external customers attributed to an individual foreign country, where those revenues are material.

Based on the Company’s assessment performed prior to the filing referred to herein, the Company concluded that additional disaggregation is not required under IFRS 15.114 and IFRS 8.32 for the following reasons.

IFRS 15 Considerations

Paragraph 114 of IFRS 15 requires an entity to disaggregate revenue from contracts with customers into categories that depict how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. A patient and their physician’s choice between VYVGART IV and VYVGART SC does not result in a material difference in the amount, the timing and the uncertainty of revenue and cash flows. As detailed above, the nature of both MoAs delivers the same therapeutic value.

Additionally, paragraph B88 of IFRS 15 requires entities to consider how the information about the entity’s revenue is presented for other purposes including:

The Company respectfully advises the Staff of the following:

In addition, considering factors in paragraph B89 of IFRS 15, the choice between VYVGART IV and VYVGART SC does not affect the type of customer. The Company’s customers under IFRS 15 consist mainly of the distributor and/or the wholesaler who carry both MoAs. The contract type or duration, sales channel, and timing of revenue recognition or cash flows are the same or similar under both MoAs. Each MoA must be approved in each geography based on local laws and regulations under the same or similar process for each MoA.

The Company therefore concludes that under IFRS, VYVGART encompasses both MoAs as a single group of similar products.

IFRS 8 Considerations

Paragraph 32 of IFRS 8 requires entities to report revenues from external customers for each product and service, or each group of similar products and services.

The Company believes that VYVGART IV and VYVGART SC constitute a single group of similar products due to their shared molecule, therapeutic purpose, integrated commercial strategy, and similar economic and revenue recognition characteristics. The Company’s presentation of product net sales (including sales of both VYVGART IV and VYVGART SC) is consistent with how the Company’s CODM reviews the Company’s financial performance and consistent with disclosures about its products outside of the financial statements.

As such, the Company believes that its current disclosure complies with the requirements of paragraph 114 of IFRS 15 and paragraph 32 of IFRS 8, and that further disaggregation is not necessary or appropriate.

The Company continues to monitor its internal reporting structure and external regulatory developments to evaluate whether changes to revenue disaggregation or segment disclosures are warranted. This evaluation is performed at each reporting period in accordance with IFRS 15 and IFRS 8.

Note 27. Contingencies, page F-46

Response: The Company respectfully submits that the FDA’s FAERS report dated June 30, 2025 (the “Report”) does not require any update to the risk disclosures on page 9 of the Form 20-F. The Company believes those disclosures remain accurate in all material respects.

The Company notes that the Report does not indicate any causality between Vyvgart Hytrulo and reported adverse events and does not reflect a benefit-risk statement on the use of Vyvgart Hytrulo in the treatment of chronic inflammatory demyelinating polyneuropathy (“CIDP”). The Company continues to monitor the reporting of any adverse effects of Vyvgart Hytrulo in the treatment of CIDP and is following the normal comment procedure with the FDA regarding the Report.

With respect to attorney advertising soliciting clients, such solicitations do not constitute an “outstanding claim or litigation.” And as such the Company respectfully submits that disclosure of such already-public solicitation is not necessary or appropriate. We do not comment on such solicitations as a matter of policy, especially given how common such solicitations are when a stock experiences price volatility.

The Company continues to evaluate its disclosure obligations on an ongoing basis and intends to make future disclosures if and when necessary.

*****

We hope that the foregoing has been responsive to the Staff’s comments and look forward to resolving any outstanding issues as quickly as possible. Please do not hesitate to contact me at kgubitz@argenx.com if you have any questions regarding the foregoing or if I can provide any additional information.