B-cell lymphoma-extra large (BCL-XL) (BCL-XL)

B-cell lymphoma-extra large (BCL-XL) is a potent anti-apoptotic member of the BCL-2 protein family that plays a critical role in regulating programmed cell death (UniProt: Q07817). Located primarily on the outer mitochondrial membrane, BCL-XL functions by sequestering pro-apoptotic BH3-only proteins and inhibiting the pore-forming activity of BAX and BAK, thus maintaining mitochondrial integrity (PubMed: 25866242). In many cancers, BCL-XL is overexpressed, providing a survival advantage to malignant cells and contributing to resistance against chemotherapy and radiation (PubMed: 31533900). Therapeutic strategies targeting BCL-XL involve BH3 mimetics that displace pro-apoptotic proteins, effectively lowering the threshold for apoptosis (PubMed: 20159561). However, a significant clinical challenge is the dependence of mature platelets on BCL-XL for survival, leading to treatment-induced thrombocytopenia (PubMed: 26461036). Recent developments include PROTACs like DT2216 and dual BCL-2/BCL-XL inhibitors designed to optimize efficacy while managing these hematologic side effects (PubMed: 31792455).

Other names

BCL2L1Bcl-XBCL2-like 1PPP1R52Bcl-xL

BCL-XL inhibitors, primarily BH3 mimetics, bind to the hydrophobic groove of BCL-XL, preventing it from sequestering pro-apoptotic proteins like BAX and BAK, thereby triggering mitochondrial outer membrane permeabilization and subsequent apoptosis (PubMed: 20159561).