CDK9 and breast carcinoma: Currently, the safety and pharmacology of the CDK2/9 dual-target inhibitor Fadraciclib (NCT04983810), as well as selective CDK9 inhibitors KB-0742 (NCT04718675) and PRT2527 (NCT05159518), are being evaluated in patients with solid tumors, including breast cancer (Table 3; Figure 12A).