GO was first approved by the FDA in 2000, withdrawn in 2010 and later re-approved for AML in 2017, but comes with a box warning for hepatotoxicity, which is most likely related to complex bystander-effects of ozogamicin [21], but not the drug carrier antibody P67.6/gemtuzumab, since the latter had no effect on the cells, if applied unconjugated [22]. Here, CD33 is linked to acute myeloid leukemia.