AZD4573 was optimized as a highly selective CDK9 inhibitor with an IC50 of less than 4 nM and exhibited a greater than 10-fold selectivity for CDK9 over CDKs 1–7 (Figures 6A, , B); it is currently regarded as a clinical candidate for the treatment of hematologic malignancies (49, 50). The gene discussed is CDK9; the disease is hematologic disorder.