VYVGART SC Approval Transforms CIDP Treatment Landscape, Driving argenx's Sustained Growth

The European Commission's June 20, 2025 approval of argenx's VYVGART SC for chronic inflammatory demyelinating polyneuropathy (CIDP) marks a watershed moment in autoimmune therapeutics. As the first novel mechanism for CIDP in over three decades, VYVGART's FcRn-blocking platform not only addresses a long-neglected disease but also unlocks a pathway to dominate a growing market. For investors, this is more than a regulatory win—it's a catalyst for sustained growth, with European market penetration and pipeline expansion positioning argenx as a leader in precision immunology.

A Neglected Market, A Breakthrough Mechanism

CIDP, a rare autoimmune disorder affecting roughly 10–15 per 100,000 people, has been a therapeutic backwater for decades. Current treatments—corticosteroids, IV immunoglobulins (IVIg), and plasma exchange—offer limited efficacy and tolerability, with 85% of patients requiring ongoing therapy and 88% experiencing residual disability. argenx's VYVGART SC breaks this cycle by targeting the neonatal Fc receptor (FcRn), a protein responsible for recycling IgG antibodies. By inhibiting FcRn, VYVGART selectively reduces pathogenic IgG, directly addressing CIDP's root cause. This first-in-class mechanism is a game-changer: no other approved therapy for CIDP operates through this pathway.

Clinical Data: Robust Efficacy, Strong Safety

The ADHERE trial, the largest CIDP study to date, underpins VYVGART's promise. Enrolling 322 patients (including 130 in Europe), the trial showed:
- 61% reduction in relapse risk (HR: 0.39, p<0.0001) vs. placebo.
- 66.5% of patients achieved clinical improvement in mobility and strength.
- 99% of participants opted to continue treatment in the open-label extension, underscoring safety and tolerability.

The most common adverse events—respiratory/urinary tract infections, headaches, and injection-site reactions—were manageable, with no new safety signals. This profile positions VYVGART as a superior option to IVIg, which requires frequent clinic visits and carries risks like thrombosis.

Addressable Market: Europe's Untapped Potential

The EU's approval unlocks a critical market. With 27 member states plus Iceland, Norway, and Liechtenstein, Europe represents an estimated 15,000–20,000 CIDP patients, many of whom are undertreated or unresponsive to existing therapies. VYVGART's subcutaneous (SC) formulation—administered via a 30-second prefilled syringe—offers a self-injection alternative to IV infusions, dramatically improving adherence. argenx's My VYVGART Path program, providing financial and educational support, further accelerates adoption.

Crucially, VYVGART's existing U.S. approval (for CIDP in 2024 and generalized myasthenia gravis in 2021) gives argenx a head start in commercializing the drug. With European sales ramping up, revenue could surge. A shows a 30% climb after the initial U.S. CIDP nod; the EU approval could propel further gains.

Pipeline Power: Beyond CIDP

The FcRn mechanism's broader potential is argenx's secret weapon. Efgartigimod, VYVGART's active ingredient, is in Phase 3 trials for myositis (ALKIVIA) and Sjögren's disease (UNITY), with Fast Track designation for the latter. If successful, these could expand the drug's addressable market to autoimmune conditions affecting millions. The ADHERE trial's success in heterogeneous CIDP patients suggests efficacy may extend to other IgG-driven diseases, such as lupus or rheumatoid arthritis.

Risks, But Momentum Outweighs Them

Skeptics might cite competition (e.g., Roche's ocrelizumab) or slow uptake in Europe. However, VYVGART's mechanism, convenience, and clinical differentiation—particularly in reducing relapse risk—should mitigate these concerns. Additionally, the $100,000+ annual cost of IVIg makes VYVGART's likely price competitive.

Investment Thesis: Position Ahead of European Rollout

argenx's stock is undervalued relative to its growth trajectory. With CIDP approvals in major markets, a robust pipeline, and a mechanism that could redefine autoimmune care, the company is primed for multi-year growth. The EU approval is the first major milestone of 2025; upcoming data from the ALKIVIA and UNITY trials (2026) will further validate the platform.

For investors, now is the time to position:
- Buy on dips below $150/share (post-EU approval momentum).
- Hold for the long term, with a 3-year price target of $300–$350/share, assuming 20% annual revenue growth.

In conclusion, VYVGART SC is more than a niche drug—it's a transformative therapy in a neglected market, with the scale to drive argenx's sustained success. As autoimmune drug development enters a precision era, investors would be wise to stake their claims early.