FDA officials urged sponsors to design long-term monitoring for CAR‑T programs aimed at autoimmune diseases, citing concerns such as secondary malignancy risk and fertility effects. The agency’s recommendation to extend follow-up mirrors expectations already applied to many gene therapies and highlights the regulatory caution surrounding cell‑based immune interventions. At the same time, researchers described progress on in vivo CAR strategies that deliver CAR constructs directly into patients rather than ex vivo manufacturing. Those technical advances promise lower-cost, scalable cell therapies but complicate safety and surveillance planning because in vivo delivery raises different biodistribution and persistence questions. Developers and regulators will need to reconcile the agency’s long-term follow-up guidance with the operational realities of in vivo CAR platforms as programs move toward clinical proof-of-concept.