Vepdegestrant

At the molecular level, vepdegestrant works as a bifunctional degrader molecule that simultaneously binds to the intracellular E3 ubiquitin ligase cereblon (CRBN) and the ligand-binding domain (LBD) of the estrogen receptor (ER). This simultaneous binding brings the target receptor and the E3 ligase together to form a stable ternary complex. Once this complex is established, vepdegestrant directly triggers the cellular ubiquitin-proteasome system (UPS) to tag the estrogen receptor via ubiquitination. The tagged receptor is subsequently directed to the cell's natural proteasome machinery for complete proteasomal degradation and elimination. Because vepdegestrant acts catalytically to cycle through multiple target proteins rather than blocking an active site structurally, it removes the estrogen receptor completely from tumor tissues. This elimination effectively downregulates downstream signaling pathways and deprives ER-dependent tumors of necessary survival signals, stopping cancer growth and causing tumors to shrink. This unique mechanism is highly effective against both wild-type estrogen receptors and specific resistance mutations, such as the mutant ESR1 (Y537S) protein, thereby overcoming endocrine resistance mechanisms that limit traditional therapies.