Johnson & Johnson entered a new chapter in in vivo CAR T after signing a collaboration with Sail Biomedicines that includes a $785 million upfront payment and an option to acquire the company for about $2.58 billion. The deal also includes milestone payments tied to development goals and gives J&J access to Sail’s in vivo cellular delivery platform. The collaboration targets immune-mediated diseases, with Sail’s program plans focused on durable immune resetting, including autoimmune applications in preclinical models. J&J gets an exclusive option to buy Sail, adding strategic optionality as large biopharma intensifies competition in next-generation cell therapy. The agreement also fits the broader pattern of platform-building deals in in vivo modalities—where therapeutic delivery engineering and manufacturing feasibility can be as important as efficacy data.