MCL1 and hematopoietic and lymphoid cell neoplasm: ➢Is a CDK9 inhibitor (IC50 of <3 nM), highly selective (>10 fold) against all other CDKs and kinases.➢Induces a rapid apoptosis in broadly across hematologic cancer models in vitro and in vivo, with a minimal effect on solid tumors. ➢Causes a rapid dose- and time-dependent decrease in RNAPII Ser2 phosphorylation with loss of Mcl-1 and MYC mRNA and protein, resulting in caspase activation and a reduced cell viability. In contrast, Bcl2 and BclxL remained unchanged ➢Is an effective short half-life treatment as single agent or in combination, for patients with hematological malignancies.