CD33 and acute myeloid leukemia: Notably, SOS is also an important side effect of gemtuzumab ozogamicin (GO), a CD33-calicheamicin ADC approved for the treatment of acute myeloid leukemia (AML), suggesting that this toxicity is related to the common cytotoxic payload calicheamicin and not specific to either CD22 or CD33 targeting (37, 38).