Proteasome Inhibitors

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Proteasome inhibitors are drugs designed to block, or inhibit, the ability of cancer cells to use certain proteins to carry out the cell cycle. When they are unable to complete this process, the result is the death of the cell.

Currently, just a few proteasome inhibitors are available on the market, but they are in wide use. They are:

Velcade
Velcade is a targeted treatment, meaning it does not kill cells indiscriminately but rather has a molecular target it seeks out. Click here for more information on Velcade and how it works. Velcade is FDA approved to treat multiple myeloma (a type of bone marrow cancer) as well as patients with mantle cell lymphoma who have failed first-line therapy.

Thalidomide and Revlimid.
These two drugs are very similar in that they work as immune system modulators. They also possess what's known as an anti-angiogenetic effect: in short, tumors create blood vessels that they use to nourish their own growth. This network-building is called angiogenesis; thus an anti-angiogenesis blocks the formation of those blood vessels. Furthermore, these drugs are believed to inhibit the proliferation of blood-borne tumor cells while at the same time boosting the number of T-cell and NK cells in the body to help bolster the immune system

In cancer treatment, thalidomide in combination with dexamethasone has been approved as a first-line treatment in some patients with a bone marrow cancer known as multiple myeloma. Thalidomide may be familiar to some for the severe birth defects the drug caused back in the late 1950s and early 1960s. The drug is still very dangerous to take for pregnant women—and plenty of safeguards are in place to be sure that pregnant women are not given the drug. However, it has been found to be safe and effective in certain other settings.

Revlimid (lenalidomide) is also an anti-angiogenetic and is also approved to treat multiple myeloma. Like thalidomide, Revlimid comes with plenty of risks, especially to a child in the womb. Furthermore, Revlimid is among the drugs given black box warning in the past few years by the FDA because of troubling reports of people on the drug developing secondary cancers including non-Hodgkin's lymphomas. The FDA issued a notice in April of 2011 which informed the public that the agency was:

"aware of results from clinical trials conducted inside and outside the United States that found that patients treated with Revlimid (lenalidomide) may be at an increased risk of developing new types of cancer compared to patients who did not take the drug. FDA is currently reviewing all available information on this potential risk and will communicate any new recommendations once it has completed its review."

Sources

MedlinePLus, thalidomide
National Cancer Institute, thalidomide
National Cancer Institute, Revlimid
FDA Ongoing Safety Review, Revlimid
Lymphoma Information Network, Velcade
BC Cancer Agency, Revlimid
BC Cancer Agency, Thalidomide

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