LL-K9-3, a selective hydrophobic tagging technology (HyT)-based degrader, specifically targets the CDK9-cyclin T1 complex, displaying DC50 values of 589 nM for cyclin T1 and 662 nM for CDK9. This compound consists of the CDK9 inhibitor, SNS 032, linked to a hydrophobic tag via a glycol linker. Notably, LL-K9-3 does not affect the degradation of other CDKs (CDK1, 2, 4, 5, 6, and 7). Tested in 22RV1 cells, it effectively reduces androgen receptor (AR) and cMyc expression by inducing the selective and synchronous degradation of CDK9 and cyclin T1.