New screening method for Anticancer drugs

Many researchers believe tumour growth is driven by cancerous stem cells that, for reasons not yet understood, are highly resistant to standard treatments. Chemotherapeutic agents may kill off 99 percent of the cells in a tumor, but the stem cells that remain can make the cancer recur or spread to other tissues in the body to cause new cancers.

Stem cells, unlike mature cells, can constantly renew themselves and are thought to be the source of cancers when, through mutations in their DNA, they throw off their natural restraints.
a team at the Broad Institute devised a way of screening for drugs that attack cancer stem cells but leave ordinary cells unharmed.

Cancer stem cells are hard to maintain in sufficient numbers, but the Broad Institute team devised a genetic manipulation to keep breast cancer stem cells trapped in the stem cell state.

The team, led by Piyush B. Gupta, screened some 16,000 chemicals, including all known chemotherapeutic agents approved by the FDA. The team reported in the Cell that 32 of the chemicals selectively went after cancer stem cells. The screening system proves for the first time that it is possible to single out cancer stem cells with drugs that leave ordinary cells alone. Only one of the 32 chemicals is approved as a drug for cancer.

Another approach to concentrating on cancer stem cells, based on the use of antibodies, was reported this month by OncoMed Pharmaceuticals.

The cancer stem cell theory has been thrust into the spotlight in the last five years with the discovery of stem cells in many types of solid tumors, including those of the breast, brain, prostate, colon, bladder and pancreas.

Source: http://www.nytimes.com/2009/08/14/health/research/14cancer.html?_r=1&8au&emc=au