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.
For treatment of multiple myeloma in patients who have not been successfully treated with at least two previous therapies.
Bortezomib is a drug that inhibits the mammalian 26S proteasome. The ubiquitin-proteasome pathway plays an essential role in regulating the intracellular concentration of specific proteins, thereby maintaining homeostasis within cells. Inhibition of the 26S proteasome prevents this targeted proteolysis, which can affect multiple signaling cascades within the cell. This disruption of normal homeostatic mechanisms can lead to cell death. Experiments have demonstrated that bortezomib is cytotoxic to a variety of cancer cell types in vitro. Bortezomib causes a delay in tumor growth in vivo in nonclinical tumor models, including multiple myeloma. Tumor cells, that is, rapidly dividing cells, appear to be more sensitive to proteasome inhibition.
Mechanism of action
Bortezomib is a reversible inhibitor of the chymotrypsin-like activity of the 26S proteasome in mammalian cells. The 26S proteasome is a large protein complex that degrades ubiquitinated proteins. The active site of the proteasome has chymotrypsin-like, trypsin-like, and postglutamyl peptide hydrolysis activity. The 26S proteasome degrades various proteins critical to cancer cell survival, such as cyclins, tumor suppressors, BCL-2, and cyclin-dependent kinase inhibitors. Inhibition of these degradations sensitizes cells to apoptosis. Bortezomib is a potent inhibitor of 26S proteasome, which sensitizes activity in dividing multiple myeloma and leukemic cells, thus inducing apoptosis. In addition, bortezomib appears to increase the sensitivity of cancer cells to traditional anticancer agents (e.g., gemcitabine, cisplatin, paclitaxel, irinotecan, and radiation).
Route of administration
Antineoplastic and Immunomodulating Agents
Chemical Actions and Uses
Cytochrome P-450 CYP1A2 Inhibitors
Cytochrome P-450 CYP1A2 Inhibitors (moderate)
Cytochrome P-450 CYP1A2 Substrates
Cytochrome P-450 CYP2C19 Inhibitors
Cytochrome P-450 CYP2C19 Inhibitors (moderate)
Cytochrome P-450 CYP2C19 Substrates
Cytochrome P-450 CYP2C9 Inhibitors
Cytochrome P-450 CYP2C9 Substrates
Cytochrome P-450 CYP2D6 Inhibitors
Cytochrome P-450 CYP2D6 Inhibitors (weak)
Cytochrome P-450 CYP2D6 Substrates
Cytochrome P-450 CYP3A Inhibitors
Cytochrome P-450 CYP3A4 Inhibitors (moderate)
Cytochrome P-450 CYP3A4 Substrates
Heterocyclic Compounds, 1-Ring
QTc-Prolonging Agents (Indeterminate Risk and Risk Modifying)
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison
T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS.
Nucleic Acids Res. 2011 Jan; 39 (Database issue):D1035-41. | PMID:21059682