The anti-CD22 immunotoxin, Moxetumomab pasudotox, achieved 29% response rate (Wayne et al., 2011), whereas the anti-CD22 calicheamicin conjugate, Inotuzumab ozogamicin, showed 57% response rate (Kantarjian et al., 2012) in relapsed/refractory ALL pediatric patients. This evidence concerns the gene CD22 and acute lymphoblastic leukemia.