argenx SE commenced a tender offer for Forte Biosciences, a clinical-stage biopharmaceutical company developing FB102, a proprietary anti-CD122 monoclonal antibody. The Belgian antibody specialist disclosed the offer Wednesday without publishing a per-share price or aggregate deal value, marking its first direct equity acquisition since the $1.9 billion Zai Lab collaboration in 2022. Forte's single asset, FB102, targets the interleukin-2 receptor beta chain and is currently in Phase 2 development for autoimmune skin conditions.
FB102 represents a differentiated mechanism within argenx's existing FcRn and complement inhibitor portfolio. The anti-CD122 candidate binds to IL-2Rβ, blocking intermediate-affinity IL-2 signaling in effector T cells while preserving regulatory T cell function—a selectivity profile that failed in Eli Lilly's failed ulcerative colitis programs but showed early promise in atopic dermatitis. Forte reported interim Phase 2 data in December 2025 showing 67% of patients achieved a 75-point improvement on the EASI scale at week 16, compared to 31% on placebo, across a 124-patient cohort. The company burned $18.2 million in cash during the nine months ending September 2025 and held $23.7 million in working capital, according to its last 10-Q filing.
The tender structure suggests argenx values the optionality of FB102's mechanism over immediate commercialization. CD122 inhibition offers a complementary path to argenx's efgartigimod, which targets neonatal Fc receptor degradation and generated $743 million in 2024 revenue across myasthenia gravis and chronic inflammatory demyelinating polyneuropathy indications. FB102's Phase 2 data in atopic dermatitis positions it against JAK inhibitors and IL-13 antagonists in a market Evaluate projects at $14.8 billion by 2030, though the asset lacks proof of concept in the systemic autoimmune conditions where argenx holds regulatory approvals. The tender allows argenx to control development timing without the earn-out or royalty obligations typical of licensing structures—a relevant consideration given Forte's cash runway extends only through mid-2026 without additional financing.
Operators should watch for tender acceptance rates by March 15, the likely close date based on standard 20-business-day SEC timelines. Forte's institutional holders—Biotechnology Value Fund owns 9.3%, Samsara BioCapital holds 7.1%—will signal whether the undisclosed premium clears private market valuations for Phase 2 dermatology assets. Secondary monitoring points include argenx's decision to continue FB102's ongoing Phase 2 trial in alopecia areata, enrollment for which stood at 78 of 120 patients as of January 2026, and any disclosure of development plans in bullous pemphigoid or cutaneous lupus, indications Forte referenced in prior investor materials but never formally initiated.
The Forte acquisition follows argenx's $680 million Breda Genetics deal in 2023, which brought nothing to market but added rare disease gene therapy capabilities the company has not yet deployed. FB102 reaches clinical proof-of-concept thirteen months faster than Breda's programs will, if ever.