Zag Bio emerged from stealth with $80 million in financing and a platform that aims to induce immune tolerance by delivering bifunctional antibodies to the thymus, the organ that produces regulatory T cells. The round included strategic support from AbbVie, Regeneron and Sanofi, underscoring big‑pharma interest in new autoimmune disease approaches. Zag’s approach targets thymic education to generate or enhance regulatory T cells (Tregs) and could offer durable control of autoimmune pathology if preclinical and early clinical data translate. The startup will use proceeds to advance lead programs and expand discovery. Backing from large immune‑focused biopharma groups also positions Zag as a potential partner or acquisition candidate as companies race to commercialize tolerogenic therapies.