MCL1 and acute myeloid leukemia: As mentioned previously, AZD4573, a therapeutic being developed by AstraZeneca, is another CDK9 inhibitor in a phase I clinical trial to test safety, tolerability, and pharmacodynamics in hematologic malignancies (NCT03263637).108 AZD4573 is more cytotoxic in AML compared to solid tumors, and this could partially be due to its role in downregulating Mcl-1 expression.