How it works
Bortezomib (originally PS-341 and marketed as Velcade by Millennium Pharmaceuticals) is the first therapeutic proteasome inhibitor to be tested in humans. The boron atom within bortezomib catalytically binds the active site of the 26S proteasome with high affinity and specificity, thereby resulting in cell cycle arrest and apoptosis. In normal cells, the proteasome is involved in degradation of ubiquitylated proteins that have been tagged for destruction because they are damaged or unneeded by the cell. However, in cancerous cells, proteasome activity degrades pro-apoptotic proteins such as p53 that would normally result in programmed cell death of the dysfunctional cells. Proteasome inhibitors such as bortezomib interrupt this process, resulting in destruction of cancerous cells. Bortezomib is approved in the U.S. for treating relapsed multiple myeloma and mantle cell lymphoma. In multiple myeloma, complete clinical responses have been obtained in patients with otherwise refractory or rapidly advancing disease.Bortezomib belongs to the class of drugs called proteasome inhibitors. Proteasomes are proteins which play an important role in growth and multiplication of cancer cells. Bortezomib blocks the action of proteasome, and reduces the growth of cancerous (actively growing) cells.