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Yesterday I promised more information about vorinostat.  Here is what ChemoCare.Com has to say about the drug:

How Vorinostat Works:

Cancerous tumors are characterized by cell division, which is no longer controlled as it is in normal tissue. “Normal” cells stop dividing when they come into contact with like cells, a mechanism known as contact inhibition. Cancerous cells lose this ability. Cancer cells no longer have the normal checks and balances in place that control and limit cell division. The process of cell division, whether normal or cancerous cells, is through the cell cycle. The cell cycle goes from the resting phase, through active growing phases, and then to mitosis (division).

The ability of chemotherapy to kill cancer cells depends on its ability to halt cell division. Usually, the drugs work by damaging the RNA or DNA that tells the cell how to copy itself in division. If the cells are unable to divide, they die. The faster the cells are dividing, the more likely it is that chemotherapy will kill the cells, causing the tumor to shrink. They also induce cell suicide (self-death or apoptosis).

Chemotherapy drugs that affect cells only when they are dividing are called cell-cycle specific. Chemotherapy drugs that affect cells when they are at rest are called cell-cycle non-specific. The scheduling of chemotherapy is set based on the type of cells, rate at which they divide, and the time at which a given drug is likely to be effective. This is why chemotherapy is typically given in cycles.

Chemotherapy is most effective at killing cells that are rapidly dividing. Unfortunately, chemotherapy does not know the difference between the cancerous cells and the normal cells. The “normal” cells will grow back and be healthy but in the meantime, side effects occur. The “normal” cells most commonly affected by chemotherapy are the blood cells, the cells in the mouth, stomach and bowel, and the hair follicles; resulting in low blood counts, mouth sores, nausea, diarrhea, and/or hair loss. Different drugs may affect different parts of the body.

Vorinostat is a Histone Deacetylase (HDAC) Inhibitor. Histone Deacetylase is an enzyme that is normally present in the cells. In some cancer cells, there is an overexpression of HDACs. It is believed that inhibition of the HDAC activity causes cell cycle arrest and cell death. The exact mechanism of action has not been fully described.

Vorinostat is unusual for a new myeloma novel therapy drug.  In most recent cases, drugs designed to fight multiple myeloma are then tried to see if they work against other cancers.  In this case, the situation is reversed.  First used in lung cancer patients, vorinostat is now being tried as an adjuct, combination therapy against several other cancers, including myeloma.  More tomorrow, including why Dr. Kenneth Anderson is spearheading clinical trials using vorinostat against multiple myeloma.

Feel good and keep smiling!  Pat