CD33 and acute myeloid leukemia: However, based on the positive outcomes of subsequent trials (NCT00927498 and NCT00091234) which used fractionated dosing strategies [99], gemtuzumab ozogamicin was re-approved by the FDA in September 2017 for treatment of adults with newly diagnosed CD33-positive AML as well as for relapsed or refractory CD33-positive AML in patients over 2 years old [98].