Scientists Map Cancer Genes; Personalized Treatments Could Be Next

In what some call a win in the war on cancer, scientists in England have for the first time managed to decipher and map cancer genomes, potentially paving the way for treatments tailored to individual patients. Full genomes for lung cancer and melanoma, a skin cancer, were mapped. "These are the two main cancers in the developed world for which we know the primary exposure," explains Professor Mike Stratton, from the Cancer Genome Project at the Wellcome Trust Sanger Institute. Lung cancer also has the highest mortality rate among cancers worldwide.All cancers are caused by abnormalities in DNA -- errors present in the cancer cells, but not in any of the normal cells of the body. With this research, published in the journal Nature this week, the scientists have compiled a complete list of the DNA abnormalities in each of the two cancers. They found tens of thousands of mutations in the cancer cells.

But not all patients exhibit the same abnormalities, making treatment more difficult. By sequencing entire patient's cancer genome and identifying the mutations, doctors could personalize treatments for individual cancer cases.

For now, though, sequencing is expensive. It took several months and $100,000 for scientists to sequence the cancer genomes. But Stratton, who led the melanoma study, estimates costs will drop to $20,000 and the time to 20 days, within a year. While this would make the process more clinically practical, the next step is to develop a cheaper and quicker process.

Lifestyle as Trigger: It Only Takes 15 Cigarettes

In the future, genome mapping would also provide indicators of lifestyle and environmental factors that can trigger the cancers. For example, the 23,000 mutations found in the lung cancer genome were mostly the result of carcinogens found in tobacco smoke. Dr. Peter Campbell, senior author on the work, put it simply: "One mutation is fixed in the genome for every 15 cigarettes smoked."

For the melanoma patients, it was exposure to ultraviolet light that caused even more DNA damage, with more than 33,000 mutations.

The studies are part of a wider effort by the International Cancer Genome Consortium, a collaborative group of research institutes from 10 countries, to sequence the genomes of 50 of the more than identified 100 cancers. It is expected to take more than five years to finish cataloging these cancer maps.

Also, of the thousands of mutations found, only a handful can turn a cell cancerous. Finding out which mutations are the culprits will be the real challenge in the coming years. Once found, those mutated genes can be used for detection as well as become important targets for future oncology drugs.

How a Revolution in Treatment Will Affect Drug Companies

Scientists have already identified some 30 genetic mutations linked to cancers, and are working on new drugs that target them. A melanoma treatment using this approach is already showing promising results in clinical trials. Drugs such as Roche's (RHHBY) Herceptin and AstraZeneca's (AZN) Iressa also target tumor cells that carry specific mutations.

Utilizing the new research would require a shift in thinking not just on the part of pharmaceuticals, but by health care and regulatory agencies as well, since cancer drugs would no longer target diseases, but certain mutations. Development costs could very well increase, as would drug costs, which are already high for cancer drugs. But their success rates could be far greater.

In a future in which cancer is a chronic treatable condition, not only would many current chemotherapy drugs become irrelevant, but the new drugs would be taken long-term, meaning the financial cost could rise.

We're still years away from such treatments becoming the norm. But pushing this forward is important not just to patients, but also to drug companies striving to remain relevant -- and profitable. Perhaps a shift to the gene-targeted thereapy approach would move the pharmaceutical industry away from what's been called the cancer drug bubble and toward drugs that promise real results.

Cancer is a leading cause of death worldwide. The disease accounted for 7.4 million deaths (around 13% of all deaths worldwide) in 2004. In the U.S., it is estimated that for 2009, 1,479,350 men and women will be diagnosed with cancer, and 562,340 will die of it.
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