Efficacy and Toxicity of Inotuzumab Ozogamicin for Treatment of Relapsed/Refractory B‐Cell Acute Lymphoblastic Leukemia in Pediatric and Young Adult Patients After CD19‐Chimeric Antigen Receptor T‐Cell Therapy

We retrospectively analyzed outcomes for nine children and young adults who were treated with inotuzumab ozogamicin (InO) for relapsed/refractory (R/R) B-acute lymphoblastic leukemia (ALL) after CD19-chimeric antigen receptor T-cell therapy (CART). After InO cycle 1, overall response rate was 77.8%; 66.7% achieved measurable residual disease (MRD)-negative remission. One-year event-free survival (EFS) was 37.5%; 1-year overall survival (OS) was 50%; 2-year EFS was 37.5%; 2-year OS was 37.5%. Median survivor follow-up is 2.9 years (0.5-4.7). Significant adverse events included prolonged cytopenias, hepatotoxicity, and post-transplant sinusoidal obstructive sydrome. InO showed promising efficacy as treatment for children and young adults with R/R B-ALL after CD19-CART. Extramedullary disease prior to InO and positive MRD after InO cycle 1 were associated with poor outcomes.