CD33

After transplant, the myeloid population lacked CD33 surface protein. The study supports the concept that CD33 can be removed from donor hematopoiesis to make it a more leukemia-selective target after transplant. CD33 was considered suitable for deletion because it is hematopoietic-restricted, common in AML, and appears dispensable for hematopoiesis. GO treatment increased the proportion of CD33-negative cells in peripheral blood after the first cycle and maintained near-complete CD33 negativity later. CD33 is therapeutically attractive but difficult to target because CD33-directed treatments can injure normal hematopoiesis. CD33 is expressed on most AML cells and also on normal myeloid cells and progenitors.