Bortezomib is the first therapeutic proteasome inhibitor
Proteasome inhibitor
Proteasome inhibitors are drugs that block the action of proteasomes, cellular complexes that break down proteins, like the p53 protein. Proteasome inhibitors are being studied in the treatment of cancer.-Examples:...

 to be tested in humans. It is approved in the U.S. for treating relapsed multiple myeloma
Multiple myeloma
Multiple myeloma , also known as plasma cell myeloma or Kahler's disease , is a cancer of plasma cells, a type of white blood cell normally responsible for the production of antibodies...

 and mantle cell lymphoma
Mantle cell lymphoma
Mantle cell lymphoma is one of the rarest of the non-Hodgkin's lymphomas , comprising about 6% of NHL cases. There are only about 15,000 patients presently in the U.S. While it is difficult to treat and seldom considered cured, investigations into better treatments are actively pursued worldwide...

. In multiple myeloma, complete clinical responses have been obtained in patients with otherwise refractory or rapidly advancing disease.

Origin and Development

Bortezomib was originally synthesized in 1995 (MG-341) at a company called Myogenics, which soon changed its name to ProScript. After promising preclinical results, the drug (PS-341) was tested in a small Phase I clinical trial on patients with multiple myeloma cancer. ProScript ran out of money and was bought by Leukosite in May 1999. Leukosite in turn was bought by Millennium Pharmaceuticals
Millennium Pharmaceuticals
Millennium Pharmaceuticals, Inc., The Takeda Oncology Company is a biopharmaceutical company based in Cambridge, Massachusetts. The Company markets Velcade for injection, a cancer product, and has a growing clinical development pipeline of product candidates...

 in October 1999. At this point in time, the project had low priority amongst other projects at the company. This changed significantly when one of the first volunteers to receive the drug in the clinical trial achieved a complete response and was still alive four years later. At the time this was a remarkable result. Later clinical experimentation indicates the possibility of a complete response in 15% of patients in a similar condition, when treated with bortezomib. In May 2003, seven years after the initial synthesis, bortezomib (Velcade) was approved in the United States by the Food and Drug Administration (FDA) for use in multiple myeloma, based on the results from the SUMMIT Phase II trial.
Another commercially available bortezomib product - Bortenat (Natco Pharma, India), reportedly contains substantially more active entity than declared, potentially and even more resulting in increase toxicity. Moreover, Bortenat has some other chemical and formulation deviations from the registered ethic product Velcade (Millennium Pharmaceuticals and Janssen-Cilag), with unclear clinical impact.



The drug is an N-protected dipeptide
A dipeptide is a molecule consisting of two amino acids joined by a single peptide bond.Dipeptides are produced from polypeptides by the action of the hydrolase enzyme dipeptidyl peptidase. Dietary proteins are digested to dipeptides and amino acids, and the dipeptides are absorbed more rapidly...

 and can be written as Pyz-Phe-boroLeu, which stands for pyrazinoic acid
Pyrazinoic acid
Pyrazinoic acid is a pyrazinamide metabolite....

, phenylalanine
Phenylalanine is an α-amino acid with the formula C6H5CH2CHCOOH. This essential amino acid is classified as nonpolar because of the hydrophobic nature of the benzyl side chain. L-Phenylalanine is an electrically neutral amino acid, one of the twenty common amino acids used to biochemically form...

 and Leucine
Leucine is a branched-chain α-amino acid with the chemical formula HO2CCHCH2CH2. Leucine is classified as a hydrophobic amino acid due to its aliphatic isobutyl side chain. It is encoded by six codons and is a major component of the subunits in ferritin, astacin and other 'buffer' proteins...

 with a boronic acid
Boronic acid
A boronic acid is an alkyl or aryl substituted boric acid containing a carbon–boron bond belonging to the larger class of organoboranes. Boronic acids act as Lewis acids. Their unique feature is that they are capable of forming reversible covalent complexes with sugars, amino acids, hydroxamic...

 instead of a carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

. Peptides are written N-terminus to C-terminus, and this convention is used here even though the "C-terminus" is a boronic acid instead of a carboxylic acid.


The boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...

 atom in bortezomib binds the catalytic site of the 26S proteasome
Proteasomes are very large protein complexes inside all eukaryotes and archaea, and in some bacteria.  In eukaryotes, they are located in the nucleus and the cytoplasm.  The main function of the proteasome is to degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks...

 with high affinity and specificity. In normal cells, the proteasome regulates protein expression and function by degradation of ubiquitinylated proteins, and also cleanses the cell of abnormal or misfolded proteins. Clinical and preclinical data support a role in maintaining the immortal phenotype of myeloma cells, and cell-culture and xenograft data support a similar function in solid tumor cancers. While multiple mechanisms are likely to be involved, proteasome inhibition may prevent degradation of pro-apoptotic factors, permitting activation of programmed cell death in neoplastic cells dependent upon suppression of pro-apoptotic pathways.

Pharmacokinetics / Pharmacodynamics

Bortezomib is rapidly cleared following intravenous administration. Peak concentrations are reached at about 30 minutes. Drug levels can no longer be measured after an hour. Pharmacodynamics
Pharmacodynamics is the study of the biochemical and physiological effects of drugs on the body or on microorganisms or parasites within or on the body and the mechanisms of drug action and the relationship between drug concentration and effect...

 are measured by measuring proteasome inhibition in peripheral blood mononuclear cells. The much greater sensitivity of myeloma cell lines and mantle cell lines to proteasome inhibition compared with normal peripheral blood mononuclear cells and most other cancer cell lines is poorly understood.


NICE may refer to:* National Independent Cadres and Elites in Iraq* National Institute for Coordinated Experiments, a fictional organisation in C.S...

 recommended against Velcade in Oct 2006 due to its cost.

The company proposed a cost reduction for multiple myeloma, and this was taken up in the UK.

Adverse effects

Bortezomib is associated with peripheral neuropathy
Peripheral neuropathy
Peripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of or trauma to the nerve or the side-effects of systemic illness....

 in 30% of patients; occasionally, it can be painful. This can be worse in patients with pre-existing neuropathy. In addition, myelosuppression causing neutropenia
Neutropenia, from Latin prefix neutro- and Greek suffix -πενία , is a granulocyte disorder characterized by an abnormally low number of neutrophils, the most important type of white blood cell...

 and thrombocytopenia
Thrombocytopenia is a relative decrease of platelets in blood.A normal human platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. These limits are determined by the 2.5th lower and upper percentile, so values outside this range do not necessarily indicate disease...

 can also occur and be dose-limiting. However, these side effects are usually mild relative to bone marrow transplantation and other treatment options for patients with advanced disease. Bortezomib is associated with a high rate of shingles, although prophylactic acyclovir can reduce the risk of this.

Gastro-intestinal (GI) effects and asthenia are the most common adverse events.

Drug interactions

Green tea extract epigallocatechin gallate
Epigallocatechin gallate
Epigallocatechin gallate , also known as epigallocatechin 3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin....

(EGCG), which had been expected to have a synergistic effect, was found by Encouse B. Golden, et al. to reduce the effectiveness of bortezomib.

Therapeutic efficacy

Two open-label, phase III trials established the efficacy of bortezomib 1.3 mg/m2 (with or without dexamethasone
Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant...

) administered by intravenous bolus on days 1,4,8, and 11 of a 21-day cycle for a maximum of eight cycles in heavily pretreated patients with relapsed/refractory multiple myeloma. Another trial demonstrated the superiority of bortezomib 1.3 mg/m2 over a high-dose dexamethasone regimen.

Further improvement of anticancer potency

Laboratory studies and clinical trial
Clinical trial
Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...

s are investigating whether it might be possible to further increase the anticancer potency of bortezomib by combining it with novel types of other pharmacologic agents. For example, clinical trials have indicated that the addition of thalidomide
Thalidomide was introduced as a sedative drug in the late 1950s that was typically used to cure morning sickness. In 1961, it was withdrawn due to teratogenicity and neuropathy. There is now a growing clinical interest in thalidomide, and it is introduced as an immunomodulatory agent used...

, lenalidomide
Lenalidomide , initially known as CC-5013 and marketed as Revlimid by Celgene, is a derivative of thalidomide introduced in 2004....

, inhibitors of vascular endothelial growth factor
Vascular endothelial growth factor
Vascular endothelial growth factor is a signal protein produced by cells that stimulates vasculogenesis and angiogenesis. It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate....

Vascular endothelial growth factor
Vascular endothelial growth factor is a signal protein produced by cells that stimulates vasculogenesis and angiogenesis. It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate....

), or arsenic trioxide
Arsenic trioxide
Arsenic trioxide is the inorganic compound with the formula As2O3. This commercially important oxide of arsenic is the main precursor to other arsenic compounds, including organoarsenic compounds. Approximately 50,000 tonnes are produced annually...

 might be beneficial. In laboratory studies, it was found that bortezomib killed multiple myeloma
Multiple myeloma
Multiple myeloma , also known as plasma cell myeloma or Kahler's disease , is a cancer of plasma cells, a type of white blood cell normally responsible for the production of antibodies...

 cells more efficiently when combined, for example, with histone deacetylase inhibitor
Histone deacetylase inhibitor
Histone deacetylase inhibitors are a class of compounds that interfere with the function of histone deacetylase.HDIs have a long history of use in psychiatry and neurology as mood stabilzers and anti-epileptics...

s, thapsigargin
Thapsigargin is non-competitive inhibitor of a class of enzymes known by the acronym SERCA, which stands for sarco / endoplasmic reticulum Ca2+ ATPase. Structurally, thapsigargin is classified as a sesquiterpene lactone, and is extracted from a plant, Thapsia garganica. It is a tumor promoter in...

, or celecoxib
Celecoxib INN is a sulfa non-steroidal anti-inflammatory drug and selective COX-2 inhibitor used in the treatment of osteoarthritis, rheumatoid arthritis, acute pain, painful menstruation and menstrual symptoms, and to reduce numbers of colon and rectum polyps in patients with familial...

. However, the therapeutic efficacy of any of these latter combinations has not yet been confirmed in cancer patients.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.