A Study to Learn More About the Study Medicine Called Inotuzumab Ozogamicin (InO) in Children (1 to <18 Years) With First Relapse ALL

This prospective, randomized, multicenter, open-label Phase 2 study is designed to evaluate the superiority of InO monotherapy vs ALLR3 after 1 cycle of induction treatment in paediatric participants (between 1 and \<18 years) with High Risk (HR) first bone marrow relapse CD22-positive BCP ALL, and to evaluate the safety and tolerability, PK and long-term efficacy. Treatment with study intervention will end after induction therapy; follow-up will continue for up to 5 years from randomization.