BCL2L11 and chronic myelogenous leukemia, BCR-ABL1 positive: However, the relatively higher resistance to either SB939 or IM in primary CML progenitors with the BIM deletion polymorphism was overcome by combining SB939 and IM which resulted in a significant reduction of at least 35-fold in the IC50 of SB939 used (single agent IC50 = 350nM; in combination, IC50 = 10nM; Fig 4D).