For comparison, tumor cell-targeting Fv-PE conjugates, such as the FDA and EMA approved moxetumomab pasudotox (Lumoxiti®), a CD22-binding immunotoxin containing a 38 kDa fragment of PE (PE38) with the C-terminal translocation sequence KDEL, achieved EC50 values in the picomolar range, significantly lower than the values mentioned in our study [77,78]. The gene discussed is CD22; the disease is neoplasm.