CD33 and leukemia: To the best of our knowledge, there are limited preclinical studies [43, 44], and currently, only 4 active clinical trials (NCT05215015, NCT04623944, NCT05247957, NCT05008575) are testing CAR-NK cells in AML patients; in addition, there is a single completed anti-AML CAR.NK-cell trial with evaluable data (NCT02944162) [45] showing that CAR.CD33-NK92 cell infusion was safe but, unfortunately, associated with minimal anti-leukaemia efficacy.