Johnson & Johnson struck a deal with Sail Biomedicines to advance in vivo CAR T therapies for immune-mediated diseases while securing an option to acquire the company. Under the collaboration, J&J will pay $785 million upfront and can move toward an additional $2.58 billion acquisition, reflecting intensifying big-pharma competition in in vivo cell therapy. Sail’s lead immune-mediated program targets CD4 and CD8 T cells and uses platform elements intended to stabilize and deliver circular RNA in vivo. In preclinical settings shared by Sail, short dosing cycles were reported to deplete B cells in lymphoid tissue, aiming for durable immune resetting. The agreement positions J&J alongside other companies that have scaled investment in in vivo CAR T, and it underscores how autoimmune indications are becoming a key proving ground for delivery and durability claims.