Beyond Inhibition: Recent Advances of Heterobifunctional Molecules Targeting CDK9.

CDK9 is a pivotal kinase in transcriptional regulatory networks. It has emerged as a promising anticancer target because of its critical role in regulating key oncoproteins such as MYC and MCL-1. While CDK9 inhibitors have shown preclinical efficacy, their clinical translation faces challenges, including narrow therapeutic windows, limited monotherapy effectiveness, and drug resistance. Targeted protein degradation (TPD) strategies, particularly PROTACs that induce CDK9 ubiquitination and degradation, offer a promising solution. These PROTACs exhibit potent and sustained antitumor effects, effectively overcoming resistance mechanisms such as MYC upregulation. Additionally, innovative approaches employing heterobifunctional molecules across various modalities have been extensively explored to target CDK9, expanding the therapeutic potential through multiple mechanisms. These advances hold promise for establishing a new paradigm in the treatment of transcriptionally addicted cancers.