A review in Immunity & Inflammation lays out the evolving case for in vivo CAR-T—shifting from multi-week, ex vivo manufacturing toward engineering T cells inside the patient. The article, led by Huji Xu of Naval Medical University with collaborators Xuanming Yang and Yujia Cai at Shanghai Jiao Tong University, maps key strategies and where clinical translation currently stands. The report centers on the manufacturing bottlenecks that limit CAR-T access, including leukapheresis, centralized genetic modification, expansion and quality control, and reinfusion after lymphodepletion. Those delays and failure points mean only a small fraction of eligible patients globally receive approved CAR-T therapies despite established efficacy. By collapsing the engineering pipeline into a single administration event, in vivo CAR-T aims to remove capacity constraints and reduce turnaround time—an approach that would require overcoming distinct delivery, safety and persistence challenges compared with conventional products.