VYVGART keeps widening argenx's lead
- VYVGART drove $4.2 billion of 2025 product net sales, up 90% year over year.
- Q4 2025 product net sales reached $1.3 billion, with $1.1 billion from the U.S.
- The company earned $1.3 billion in 2025, its second straight profitable year.
- The FDA resolved the CIDP worsening review with label guidance for switching from IVIg.
- The May 2026 U.S. approval expanded VYVGART to all adult gMG patients.
A rare disease winner with proof
argenx has moved from promising biotech to profitable drug company. VYVGART and VYVGART Hytrulo produced $4.2 billion of 2025 product net sales, up 90% from the prior year. Q4 2025 alone reached $1.3 billion. The company also reported $1.3 billion of profit in 2025, its second profitable year in a row.
The bull case is that VYVGART can keep adding patient groups without losing pricing power. The drug already reaches more than 19,000 patients globally across gMG, CIDP, and ITP, and argenx wants 10 labeled indications by 2030. The positive Phase III ADAPT OCULUS study in ocular MG could add about 7,000 addressable patients, and the May 2026 FDA approval expanded VYVGART and VYVGART Hytrulo to all adult gMG patients in the U.S.
The bear case is more about execution than survival. CIDP growth may slow after the easiest switch patients move from IVIg to VYVGART. U.S. rebates and discounts, called gross-to-net adjustments, rose with the move toward self-injection under the pharmacy benefit. They stabilized in Q3 and Q4 2025, but investors still need to watch whether that holds.
High-priced drugs, narrow diseases
argenx sells biologic medicines for rare autoimmune diseases. These drugs are complex antibody medicines, not simple pills. The main product is efgartigimod, sold as VYVGART for IV use and VYVGART Hytrulo for under-the-skin use.
Most revenue comes from treating generalized myasthenia gravis, or gMG, and chronic inflammatory demyelinating polyneuropathy, or CIDP. Both are serious immune-driven nerve or muscle diseases. The value pitch is simple: if VYVGART can reduce harmful antibodies and improve daily function, payers may accept a high price because the patient groups are small and the need is high.
The prefilled syringe matters because it lets more patients self-administer. That can grow volume, but it also shifted more U.S. reimbursement from Medicare Part B medical coverage to Part D pharmacy coverage. That shift raised gross-to-net discounts earlier in 2025. Management said U.S. net pricing and gross-to-net adjustments were in line with the prior quarter in both Q3 and Q4 2025, which eased the margin worry for now.
One engine, several shots
VYVGART and VYVGART Hytrulo in gMG
This is the core franchise. The May 2026 U.S. approval expanded use to all adult gMG patients, regardless of antibody status.
VYVGART Hytrulo in CIDP
CIDP is the newer major launch. The key question is whether growth continues after early patients switch from IVIg.
VYVGART in ocular MG
The Phase III ADAPT OCULUS study was positive. argenx plans an sBLA filing, and the company estimates about 7,000 added addressable patients.
Efgartigimod in other autoimmune diseases
Phase II proof-of-concept data were positive in myositis and Sjogren's. The company is also advancing efgartigimod into Phase III for Graves' disease.
Empasiprubart
This is a second pipeline antibody in registrational studies for MMN and CIDP. The MMN readout expected in Q4 2026 is a major pipeline test.
ARGX-119
ARGX-119 is in a registrational study in congenital myasthenic syndrome, or CMS. It gives argenx another chance outside the VYVGART franchise.
Still U.S.-heavy
This mix uses Q4 2025 product net sales by region: $1.1 billion in the U.S., $63 million in Japan, $110 million in rest of world, and $26 million from product supply to Zai Lab in China. The company is highly concentrated in VYVGART, even though it sells across several regions.
What could break the story
CIDP growth stalls after switch patients
High impact · Medium oddsThe early CIDP launch benefited from patients switching from IVIg. That pool may not repeat forever. If new patient starts slow, the market may question how large the CIDP opportunity really is.
Gross-to-net discounts rise again
Medium impact · Medium oddsSelf-injection moved more U.S. use into pharmacy benefit channels. That raised gross-to-net discounts earlier in 2025. Q3 and Q4 stabilized, but a renewed rise would pressure profit even if prescriptions grow.
Switching label guidance changes doctor behavior
Medium impact · Medium oddsThe FDA review of CIDP worsening in FAERS ended with a favorable outcome and label guidance for switching from IVIg. That removed a major overhang. Still, the real test is whether doctors prescribe as freely after the updated guidance.
Pipeline readouts disappoint
High impact · Medium oddsargenx wants 10 labeled indications by 2030. That plan depends on repeated clinical wins, not only commercial execution. Empasiprubart in MMN, efgartigimod in ocular MG, and newer indications like Graves' disease all carry trial risk.
Biosimilars arrive after exclusivity
High impact · Low oddsVYVGART has a long runway, but not a permanent one. The base regulatory exclusivity period is expected to run until December 2033 in the U.S. and August 2032 in the EU. As those dates get closer, copycat biologic risk becomes more important.
In one breath
What does argenx sell?
argenx sells VYVGART and VYVGART Hytrulo, versions of efgartigimod. They are antibody medicines used for rare immune nerve and muscle diseases such as gMG and CIDP.
Why is VYVGART important to ARGX stock?
VYVGART is the main revenue engine. It generated $4.2 billion of 2025 product net sales and helped argenx earn $1.3 billion of profit that year.
What changed with the seronegative gMG approval?
In May 2026, the FDA expanded VYVGART and VYVGART Hytrulo to all adult gMG patients in the U.S. That includes patients who do not test positive for the original AChR antibody group.
What is the biggest risk for argenx now?
The main near-term risk is whether CIDP keeps growing after early switch patients. A second risk is whether U.S. discounts stay stable as more patients use the self-injection format.