Zag Bio launched with an $80 million Series A to develop thymus‑targeted bifunctional antibodies designed to induce regulatory T cells (Tregs) for autoimmune disease. The round included strategic backing from AbbVie, Regeneron and Sanofi, signaling large‑pharma interest in tolerizing approaches that could deliver durable immune control. Zag’s technology aims to redirect tolerizing antigens to the thymus to retrain central tolerance; the company plans preclinical and IND‑enabling work to advance candidates toward first‑in‑human testing. Backers cited the platform’s potential to create one‑time or disease‑modifying treatments for autoimmune indications. The financing and blue‑chip investors highlight continued appetite for novel immunology modalities focused on durable immune reprogramming rather than chronic immunosuppression.