Argenx’s $2B Forte Bio Acquisition Brings Autoimmune Playbook to Prevalent Disorders

Argenx established itself in immunology with a single drug offering potential use across a range of rare inflammatory disorders. The biotech is now expanding to more prevalent conditions through a $2.2 billion deal to buy Forte Biosciences, a company whose lead asset has encouraging clinical data in two common conditions with few treatment options.

The deal announced Monday — Argenx’s first acquisition — comes weeks after Forte reported positive Phase 1b results for its drug in vitiligo, a skin disorder. The antibody had previously demonstrated clinical proof of concept in a separate Phase 1b test in celiac disease. Argenx CEO Karen Massey said the novel biology of this drug and the unmet needs it could address were key considerations for acquiring Forte and its asset, which her company had been following for years. Also important is the Forte drug’s pipeline-in-a-product potential.

“We like molecules where we can pursue multiple indications,” Massey said during a Monday morning conference call. “One of the reasons for that is that it gives us multiple paths for success and multiple paths for growth.”

Amsterdam-based Argenx knows a thing or two about developing drugs with pipeline-in-a product potential. The company’s only commercialized asset to date is efgartigimod, brand name Vyvgart. An intravenously infused formulation of the antibody fragment is approved for treating two rare inflammatory disorders. An injectable version is approved in yet another, and clinical testing is ongoing in seven more indications. Across Vyvgart’s approved indications, Argenx reported $4.2 billion in revenue in 2025, a nearly 90% increase compared to the prior year.

Forte’s FB102 is a monoclonal antibody designed to bind to and block CD122, a subunit of the IL-2 and IL-15 receptors on immune cells that can lead to proliferation and activation of these cells. By inhibiting CD122, the Forte drug is intended to modulate pathogenic T cell biology while preserving the activity of regulatory T cells (Tregs), immune cells that dampen excessive immune responses. There are currently no FDA-approved CD122-targeting antibodies.

Following the positive Phase 1b results in celiac disease last year, Dallas-based Forte proceeded to Phase 2 testing. Data are expected in the fourth quarter of this year. In vitiligo, which leads to the loss of pigment and color in the skin, Forte reported Phase 1b results showing statistically significant improvement measured according to a scale used to assess disease severity on a patient’s face. Adverse events were classified as mild or moderate. Yet another Phase 1b test is evaluating the Forte drug in the hair loss disorder alopecia areata; the company has said it expects preliminary data this year.

The Forte acquisition complements Argenx’s portfolio, Massey said. Rather than looking at autoimmune diseases from the standpoint of rare or common, she said an Argenx-like indication is a severe autoimmune condition with a significant unmet need. There are no FDA-approved therapies for celiac disease, a gut disorder that develops as an autoimmune response to gluten. This condition is managed by maintaining a gluten-free diet. Vitiligo has only one FDA-approved treatment, Opzelura. This drug is a topical formulation of Incyte’s JAK inhibitor, ruxolitinib.

With Vyvgart, Argenx showed it can establish leadership in underserved markets, Massey said. That experience gives the company confidence it can apply the same playbook to FB102 in the lead indications as well as other autoimmune disorders. Massey said her company would evaluate other potential indications for the Forte drug in coming months.

In a research note, Leerink Partners analyst Thomas Smith said the Forte acquisition diversifies Argenx’s pipeline with a drug that brings a different mechanism of action and the potential to address autoimmune diseases affecting millions of patients versus the thousands of rare disease patients treated by Vyvgart.

Argenx already owns some of Forte, having participated in the biotech’s $150 million stock offering in April. The amount of Forte stock Argenx owns remains undisclosed. William Blair analysts Matt Phipps and Myles Minter said in a research note that the acquisition is not a complete surprise in light of Argenx’s recent investment in Forte. They added that Argenx had $5.2 billion in cash as of the end of the second quarter of this year along with cash flow from Vyvgart. From that strong financial position, the bank expects Argenx will continue to evaluate business development opportunities. As for Argenx’s internal pipeline, the next key Vyvgart event is an expected data readout in myositis, an autoimmune disorder affecting muscles.

“While the focus for investors remains on Phase 3 ALKIVIA trial in myositis patients coming this quarter, we do believe FB102 adds another intriguing asset with near-term catalysts that can likely be moved into late-stage development in 2027,” the William Blair analysts said.

Forte is not the only company in the clinic with a CD122-inhibiting antibody. First Tracks Biotherapeutics, which launched in April as a publicly traded company with assets from AnaptysBio, has a pipeline that includes ANB033, a CD122-targeting antibody in Phase 1 b development for celiac disease and eosinophilic esophagitis. Meanwhile, Teva Pharmaceutical has the IL-15-blocking antibody TEV-’408, which is in early clinical development for celiac disease and vitiligo.

According to the terms of the acquisition agreement, Argenx will pay $77 in cash for each share of Forte it does not already own, valuing the biotech at about $2.2 billion. That price represents a premium of about 86% to Forte’s average stock price since the company’s July 9 report of Phase 1b data in vitiligo. The companies expect to close the transaction in the current quarter.

Photo illustration: Cheng Xin, Getty Images