As part of the Associazione Italiana di Ematologia Oncologia Pediatrica and the Berlin-Frankfurt-Münster Acute Lymphoblastic Leukemia (AIEOP-BFM ALL) clinical trial, she had been randomized to receive blinatumomab, a bispecific T-cell–engaging antibody targeting CD19-expressing B cells; her last dose was 6 months before admission (5). Here, CD19 is linked to acute lymphoblastic leukemia.