BCL-2

Class

Small molecule BCL-2 inhibitor

Pathway

Intrinsic (mitochondrial) apoptosis pathway

BCL-2 is a protein that helps cells survive by blocking apoptosis, the programmed cell death process that normally eliminates damaged or unneeded cells. It works within the intrinsic, or mitochondrial, apoptosis pathway, where a family of related proteins constantly balance pro-survival and pro-death signals at the mitochondrial membrane. Many cancer cells, particularly certain blood cancers, produce excess BCL-2, allowing malignant cells that should die to persist and accumulate. Small molecule BCL-2 inhibitors are designed to occupy the groove on BCL-2 that normally sequesters pro-apoptotic partner proteins, releasing them so they can trigger mitochondrial outer membrane permeabilization and commit the cell to death. Because this approach exploits a survival dependency that many tumor cells have come to rely on, it can selectively induce apoptosis in malignant populations while sparing normal cells that are less reliant on BCL-2 for survival. This mechanism is broadly relevant across hematologic malignancies such as leukemias and lymphomas, where BCL-2 overexpression is common, and is being explored in various combination strategies. The approach represents a rational, structure-based way of directly re-enabling a cell's own death machinery rather than relying on external immune or genotoxic mechanisms.