Argenx's $9.5B sell-off exposes the risk in its Vyvgart growth strategy

On Oct. 8, Argenx (Euronext & Nasdaq: ARGX) stopped¹ UNITY, its Phase 3 trial of Vyvgart Hytrulo, the under-the-skin form of efgartigimod, in moderate-to-severe Sjögren's disease.

An independent data monitoring committee concluded after an interim analysis that the study could not meet its primary endpoint. Argenx said no new safety signals appeared.

The shares were down 16% by late morning in Europe, wiping about €8.5 billion ($9.5 billion) off Argenx's market value, according to Reuters². In New York they fell as much as 15%, then closed³ down $109.81 at $818.63, a drop of about 12%.

What failed: Vyvgart's next step into rheumatology

Sjögren's is a chronic autoimmune disease in which the immune system attacks the glands that make tears and saliva. It can also affect joints, lungs, kidneys and nerves. Novartis estimates⁴ it affects about 0.25% of the population, with roughly half of cases undiagnosed. No targeted therapy is approved in the US or Europe.

Vyvgart built its sales in neurology, in generalized myasthenia gravis (gMG) and CIDP. Argenx sees rheumatology as a potential new growth platform, Reuters reported, and Sjögren's was a major part of that push, though William Blair expected it to be smaller than myositis.

What UNITY tested:

• Weekly efgartigimod injections versus placebo, randomised 1:1, on top of standard care.
• Adults who tested positive for anti-Ro/SSA antibodies and had moderate-to-severe systemic disease (clinESSDAI of 6 or more).
• A primary endpoint of change in clinESSDAI, a disease-activity score, at Week 48.

William Blair analysts said the futility analysis relied on more than 500 of the 630 patients enrolled, according to Fierce Pharma⁵. They said that may point to an earlier time point, such as Week 24. Argenx has not released efficacy numbers. It says it will analyse the full dataset after database lock.

We are disappointed by this outcome, most of all for people living with Sjögren's disease

Luc Truyen, chief medical officer, Argenx

Why the futility call matters more than the lost indication

Several analysts had left Sjögren's out of their models because it was high risk, according to BioPharma Dive⁶. Results weren't expected until the second half of 2027. TIKR⁷ put consensus revenue at about $9.33 billion for 2028, and said Sjögren's was unlikely to be much of that figure.

So the sell-off was about the growth story. Much of Argenx's value rests on the belief that one drug can treat several autoimmune diseases.

A small Phase 2 study called RHO⁸ had raised hopes. It randomised 34 patients, and 45.5% on efgartigimod responded at Week 24, compared with 11.1% on placebo. RHO was not a direct preview of UNITY, though. It used the intravenous form, a shorter treatment period and a different response measure called CRESS.

Even so, the gap between the two trials raises a fair question about how much weight investors should put on small early studies. William Blair analysts noted that Sjögren's trials have been held back by high placebo response.

Vyvgart's record beyond its first indication

• Generalized myasthenia gravis: approved. The founding indication, expanded⁹ to all adult serotypes, including seronegative patients, in May 2026.
• CIDP: approved in the US in June 2024. The second major market.
• Ocular myasthenia gravis: positive Phase 3¹⁰ in February 2026, now filed with the FDA.
• Pediatric gMG: under FDA priority review, with a target decision in February 2027.
• Myositis: positive Phase 3¹¹ in August 2026. The IMNM subtype hit significance and a filing is due by year-end. The DM subtype did not (p=0.1093), so Argenx plans an extra study.
• Primary ITP: mixed. The IV trial succeeded and Japan approved the drug, but the subcutaneous trial failed¹² in 2023. A new Phase 3 reads out in the first half of 2027.
• Pemphigus: late-stage failure in 2023.
• Thyroid eye disease: Phase 3 stopped for futility¹³ in December 2025.
• Sjögren's disease: Phase 3 stopped for futility in October 2026.

Investors have already taken much of it back

The share price recovered quickly. Argenx reported¹⁴ third-quarter Vyvgart sales of $1.72 billion, up 54% from a year earlier, and said it remains on track for its Vision 2030 goals. By Oct. 30 its Nasdaq shares¹⁵ stood at $892.87, about 4% below where they were before the news.

Given Argenx's premium valuation, Phase 3 setbacks have historically resulted in sharp pullbacks that ultimately present buying opportunities

Matt Phipps, analyst, William Blair, via BioPharma Dive

The same day as UNITY, Argenx reported positive Phase 2 data for FB102 in celiac disease, and it is moving the drug to Phase 3. TD Securities analyst Yaron Werber models $988 million in peak sales there and called the result a step toward a second franchise, according to BioPharma Dive.

The race moved on without Argenx

Even a positive UNITY readout in late 2027 would probably have put Vyvgart third or later to market in Sjögren's. Rivals are well ahead:

• Ianalumab (Novartis): two positive Phase 3 trials, FDA Breakthrough Therapy designation and priority review¹⁶. The decision has slipped. Novartis had pointed to a third-quarter approval, and FDA action is now expected by the end of 2026, according to a summary of its Oct. 27 earnings call¹⁷.
• Dazodalibep (Amgen): met its primary endpoint in Phase 3 OASIZ-301. Amgen released the numbers¹⁸ on Oct. 27 and presents them at the ACR meeting on Nov. 11. A second Phase 3, OASIZ-303, is due to complete in the fourth quarter.
• Telitacicept (Vor Bio and RemeGen): approved in China¹⁹ in June 2026, which Vor Bio calls the first regulatory approval anywhere for Sjögren's. A global Phase 3 is enrolling²⁰.
• Nipocalimab (Johnson & Johnson): an FcRn blocker, like Vyvgart. It met its clinESSDAI endpoint²¹ in the Phase 2 DAHLIAS trial and is now in Phase 3 (DAFFODIL). Immunovant is also developing a drug in the class.

The winners so far have not cleared a high bar. Both ianalumab and dazodalibep beat placebo by less than two points on ESSDAI, because placebo patients also improved.

What to watch next

1. The FDA's ianalumab decision, expected by year-end, which could produce the first targeted Sjögren's drug in the US.
2. Empasiprubart's Phase 3 MMN readout in December. A clean result would show Argenx's next molecule can carry growth beyond Vyvgart.
3. The IMNM filing by year-end, the first regulatory test of Vyvgart's rheumatology push.
4. UNITY's full dataset, including whether any subgroup, such as patients with high autoantibody levels, responded.
5. J&J's DAFFODIL trial, the clearest read on whether FcRn blockade has a future in Sjögren's.
6. ADVANCE-NEXT in primary ITP, due in the first half of 2027.
7. Full-year results on Feb. 25, 2027, for updated guidance and any change to the Vision 2030²² targets.