CD19 and acute lymphoblastic leukemia: Several novel agents were recently approved for relapsed/refractory (r/r) ALL, including blinatumomab (a bispecific T‐cell engager against CD19), tisagenlecleucel and brexucabtagene autoleucel (chimeric antigen‐receptor T‐cells against CD19), and inotuzumab ozogamicin (antibody‐drug conjugate against CD22).