Getting Iressa to People Who Need It
Lung cancer is the leading cause of cancer deaths worldwide, and current treatments for lung cancer remain only marginally effective. One drug recently approved for lung cancer treatment, Iressa, targets a protein named EGFR. Doctors have observed that tumor cells contain significantly more EGFR than normal cells, suggesting that it may be an important protein for tumor growth. Yet even though many tumors have a lot of EGFR protein, only a small number of them are successfully treated by Iressa. Why is this? Until recently that was a mystery, but this month two independent groups at the Dana Farber Cancer Institute and Massachusetts General Hospital identified a possible explanation for this phenomenon. They discovered that tumor cells that are killed by Iressa have one form of the EGFR protein, while the tumor cells that resist Iressa treatment have a different form. This suggests that only patients that have the first form of EGFR in their tumors will benefit from Iressa. Doctors will now be able to first identify which form of EGFR is present in a patient's tumor, and then prescribe Iressa to only the patients that are predicted to be successfully treated.
Pharmacogenomics
The story of Iressa exemplifies what many health professionals believe is the future of medicine, a new approach to treatment termed pharmacogenomics, or personalized medicine. The essence of pharmacogenomics is recognizing the fact that each of us has a unique genetic code that makes some drugs work for some people, but not for others. By understanding how our genes influence how well a drug will work, doctors will be able to prescribe specialized drugs that fit each individual’s genetic makeup. There are a number of benefits to a pharmacogenomic approach to medicine, as opposed to our current “one size fits all” treatment approach. For instance, as in the case of Iressa, a drug can be directed towards only the people that have the genes needed to benefit from it. This improves treatment quality for patients, as well as reduces health care costs, since we will no longer need to spend time trying drugs on people for whom they won’t work. Also, just as our genetic makeup can affect our responsiveness to a drug, it can also affect the type and severity of side effects that one suffers. Knowing the likelihood of adverse side effects beforehand will give doctors the power to avert these side effects by altering either the drug or the drug dosage. Pharmacogenomics, then, is a powerful new approach to medicine that has the potential to dramatically transform the healthcare system.
More information can be found at:
- Dana-Farber Cancer Insitute press release on Iressa study: http://www.dfci.org/abo/news/press/042904.asp
- What is pharmacogenomics? http://www.ornl.gov/sci/techresources/Human_Genome/medicine/pharma.shtml
