A phase 2 study assessed inotuzumab ozogamicin in 48 pediatric and adolescent patients with R/R B-ALL, among whom 10 (20.8%) underwent prior CD19 CAR-T cell therapy, 1 (2.1%) received CD22 CAR-T cell infusion, and 14 (29.2%) were treated with blinatumomab (a CD3/CD19 bispecific T cell engager). Here, CD19 is linked to acute lymphoblastic leukemia.