An 86% premium over an 18-day trading window is an unusual signal. When argenx agreed to pay $77 per share, roughly $2.2 billion in total equity value, for Forte Biosciences, it was not betting on a speculative pipeline. It was pricing in Phase 1b data in two separate autoimmune indications, vitiligo and celiac disease, that had already demonstrated statistically significant treatment benefit. The deal converts an earlier strategic investment into full ownership, which means argenx was watching this biology closely before the positive readouts accelerated the timeline to acquisition.
The clinical substance here centers on FB102, an anti-CD122 antibody that targets the shared beta subunit of the IL-2 and IL-15 receptor complex. This mechanism suppresses pathogenic T-cell and NK-cell activity, a dimension of immune dysregulation that sits apart from the FcRn and complement pathways argenx has built its core portfolio around. Celiac disease is a useful proof-of-concept battleground: prior work with AMG 714, an anti-IL-15 receptor antibody, showed that blocking this pathway can attenuate gluten-driven intestinal inflammation, validating the general biology before FB102 entered the picture. Approved pharmacologic options for celiac disease remain limited, and the failed Phase 3 history of larazotide acetate illustrates how difficult it has been to move beyond strict dietary management. FB102’s Phase 1b celiac data from last year was strong enough that argenx is now waiting on Phase 2 results expected in the second half of 2026, results it will own entirely when the deal closes in Q3.
The strategic logic extends beyond any single indication. Alopecia areata is named as a third target, and the company frames FB102 explicitly as a pipeline-in-a-product, meaning the asset’s value is in its reach across T-cell and NK-cell driven diseases rather than in one approval. That framing carries real development risk: multi-indication antibody programs require parallel trial infrastructure, and each new indication demands its own regulatory evidence package. argenx is funding the entire $2.2 billion from cash on hand, so there is no dilution, but it does signal a material capital allocation choice at a moment when the company is simultaneously advancing efgartigimod, empasiprubart, adimanebart, and ARGX-121.
The number to track is the Phase 2 celiac readout expected before year-end. Vitiligo provided statistical proof-of-concept, but celiac disease carries a more demanding efficacy bar because intestinal histology and patient-reported symptom outcomes must move together. If the Phase 2 data holds, argenx will have two indication-level validations to anchor the broader expansion strategy. If it disappoints, the $2.2 billion price tag will demand a harder look.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
