CD33 and acute myeloid leukemia: Based on the overall positive outcomes achieved in above three investigator-led clinical trials, thus the Mylotarg® was re-approved by the FDA in 2017.149,151,152 Recently, a new indication of gemtuzumab ozogamicin was approved by the FDA for the treatment of newly-diagnosed CD33-positive AML to include pediatric patients 1 month and older.153 The rare listing experience gained from the withdrawal and re-approval of gemtuzumab ozogamicin provides important reference for the development and clinical trials design for ADCs.