Argenx Acquires Forte Biosciences for $2.2B, Adding Anti-CD122 Antibody FB102 to Immunology Pipeline

Argenx (Nasdaq: ARGX) agreed to acquire Forte Biosciences (Nasdaq: FBRX) for $77 per share in cash, a deal valued at approximately $2.2 billion that adds the first-in-class anti-CD122 antibody FB102 to argenx’s immunology pipeline. The transaction was announced July 27, 2026.

The $77 per share price represents a premium of approximately 86% to Forte Biosciences’ volume-weighted average price since the company reported positive Phase 1b data in vitiligo on July 9. Forte Biosciences closed at $54.78 on July 25, the last trading day before the deal was announced, meaning the offer is a 40.5% premium to the prior close. The deal is funded entirely from argenx cash on hand and is expected to close in Q3 2026, subject to customary closing conditions including a majority tender of Forte shares and Hart-Scott-Rodino antitrust clearance.

The prize: FB102

The target asset is FB102, a first-in-class anti-CD122 antibody that targets pathogenic T-cell and NK-cell activity through the interleukin-2/IL-15 receptor beta pathway. Forte Biosciences reported positive Phase 1b data in vitiligo earlier in July, with a 29.6% mean FVASI improvement from baseline at week 24 (p=0.020), and statistically significant improvements observed as early as day 64. Positive Phase 1b data in celiac disease was shared in 2025, with Phase 2 data expected in the second half of 2026.

argenx CEO Karen Massey called FB102 a “pipeline-in-a-product” opportunity, noting its potential to address vitiligo, celiac disease, alopecia areata, and additional autoimmune diseases. The asset complements argenx’s existing portfolio built around Vyvgart (efgartigimod), which generated $4.2 billion in global net sales in 2025, up 90% year-over-year.

Why argenx is paying up

The acquisition reflects argenx’s “Vision 2030” strategy to treat 50,000 patients across 10 indications with five late-stage molecules by the end of the decade. FB102 adds a mechanism distinct from argenx’s FcRn franchise: rather than modulating IgG antibody levels through FcRn blockade, FB102 targets the T-cell and NK-cell arm of the immune system through CD122 biology.

argenx had previously made a strategic investment in Forte Biosciences, so the acquisition deepens an existing relationship. Arjen Lemmen, argenx’s VP of corporate development and strategy, noted the deal is not necessarily at the “standard level of validation” the company requires every time, but said argenx’s role as a biotech innovator is to “take calculated risks” on novel target biology.

What to watch

FB102 enters argenx’s pipeline at the Phase 1b/Phase 2 stage. The next catalyst is the Phase 2 celiac disease data expected in the second half of 2026. argenx will also need to advance FB102 into Phase 2 trials in vitiligo and potentially alopecia areata. The deal is expected to close in Q3 2026.

argenx closed at $888.82 on July 27, down 3.2% from its $918.22 close on July 25, giving it a market capitalization of roughly $51 billion. The decline reflects some investor concern about the premium paid for a Phase 1b asset. Forte Biosciences closed at $76.50, just $0.50 below the $77 offer price, signaling that the market expects the tender offer to close without a competing bid.

BioSpace coverage | BusinessWire press release | Fierce Biotech

For context on argenx’s immunology franchise and the FcRn competitive market, see our JNJ nipocalimab JASMINE SLE analysis.