Inotuzumab ozogamicin (Besponsa®; Pfizer) as a CD22-targeting antibody-drug conjugate (ADC) is approved for adult R/R pre-B ALL, and for the treatment of patients with relapsed or refractory ALL, a group that otherwise has a poor prognosis with standard chemotherapy [164]. This evidence concerns the gene CD22 and acute lymphoblastic leukemia.