SGN-CD123A was highly active in 11 of 12 AML cell lines tested (mean IC50, 6 ng/ml; range of 0.02 to 38 ng/ml), including 4 of 5 MDR-positive cell lines, whereas it was inactive in CD123-negative HEL92.1.7 AML cells. SGN-CD123A was also active against 20 of 23 primary ...