Cyclin-dependent kinase 9 and B-cell lymphoma 2 apoptotic pathway (CDK9-BCL-2 pathway)

The CDK9–BCL-2 apoptotic pathway is a therapeutic axis that leverages the synergy between transcriptional regulation and the intrinsic apoptotic machinery [2, 12]. Cyclin-dependent kinase 9 (CDK9) is the catalytic subunit of the positive transcription elongation factor b (P-TEFb) complex, which is essential for the transcription of short-lived anti-apoptotic proteins, most notably Myeloid Cell Leukemia-1 (Mcl-1) and the oncogene Myc [4, 9]. B-cell lymphoma 2 (BCL-2) is a key regulator of the intrinsic apoptotic pathway, and its inhibition by drugs like venetoclax is a standard treatment for several hematological malignancies [3, 15]. However, resistance to BCL-2 inhibitors often arises through the upregulation of Mcl-1, which can sequester pro-apoptotic proteins and prevent cell death [6, 12]. By inhibiting CDK9, the rapid downregulation of Mcl-1 sensitizes cancer cells to BCL-2 inhibition, effectively overcoming this resistance mechanism and synergistically inducing apoptosis [3, 5]. This combination strategy is currently being evaluated in clinical trials for patients with acute myeloid leukemia (AML) and other B-cell malignancies to improve therapeutic efficacy and durability [11, 12].

Other names

CDK9/BCL-2 axisCDK9-Mcl-1-BCL-2 axisP-TEFb/BCL-2 pathway

Inhibition of CDK9 downregulates short-lived anti-apoptotic proteins like Mcl-1 and Myc, which removes a major resistance mechanism to BCL-2 inhibitors, thereby synergistically inducing apoptosis.