Sanofi struck an exclusive worldwide license for Kali Therapeutics’ trispecific T‑cell engager KT‑501, paying $180 million in up‑front and near‑term payments with more than $1 billion in downstream milestones and tiered royalties. Kali had just dosed the first patient in a phase Ia study for KT‑501 in rheumatoid arthritis when the deal was announced. Sanofi will take global rights while Kali retains program economics tied to milestone and royalty structures; the transaction marks Sanofi’s renewed investment in T‑cell engager approaches for autoimmune indications.