BACKGROUND: CD19-directed chimeric antigen receptor T-cell therapy tisagenlecleucel has shown promising results in the treatment of pediatric patients with relapsed/refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL). However, around 50% of patients relapse after tisagenlecleucel. Following multiple relapses, limited treatment options are left, and the prognosis is dismal. We report on four pediatric patients who relapsed after tisagenlecleucel and were treated with inotuzumab ozogamicin (InO). CASE: Four patients with BCP-ALL received tisagenlecleucel after second relapse (3/4) or refractory disease at first relapse (1/4). Three patients relapsed with CD19 CONCLUSION: InO can be used successfully and safely for the treatment of CD22