A few years ago, gefitinib was written off as an ineffective drug treatment for lung cancer. This conclusion was based on a 2004 study that found no correlation between gefitinib and prolonged lifespan among lung cancer participants. However, scientists who revisited the drug eventually found that gefitinib is exceptionally effective in treating a small minority of lung cancer patients.
Through additional research, scientists were able to determine that individuals who harbored a lung cancer tumor that exhibited a specific mutant form of EGFR (epithelial growth factor receptor) responded well to gefitinib. As a result, the drug currently serves as a viable treatment option for a select group of patients.
This example is just one of several that shows the importance of targeted cancer treatment. While past treatment philosophies have focused on treating all individuals with a specific type of cancer in the same way, new research shows that a variety of cancer subsets within a cancer type are more susceptible to certain types of treatment.
This shift in cancer treatment has been in the works for several years. Unfortunately, success stories have been slow to materialize. According to experts such as MIT professor Michael Yaffe, one reason for this is the breakdown in communication between cancer biologists who identify mutations and doctors in the clinic who put such knowledge to application.
As Yaffe explains, “We need a better translational mechanism for being able to take the things we discover here at MIT and elsewhere, and test them directly in large clinical trials. That’s sort of a bottleneck that I think everyone is aware of.”
Despite such hurdles as this, a handful of landmark targeted cancer treatments have already been identified. Most notably is the success of Gleevec, a drug that has single-handedly made CML (a rare type of leukemia) a manageable chronic illness.
Currently, breast cancer is one of the few cancer types to be routinely screened for specific genetic mutations. This is because the presence of specific mutations may indicate whether or not Herceptin will serve as an effective treatment. However, many scientists foresee a future in which all cancer patients receive a comprehensive screening immediately following diagnosis.
According to Alan D’Andrea of the Dana-Farber Cancer Institute, the purpose of such default screening would be to identify the potential benefits of conventional treatment. “If we could identify up front the patients who are not going to respond to conventional drugs, we could immediately put them on an experimental therapy.”
Before such a vision becomes a reality, however, viable pathways must be identified to target. Additionally, safe and effective drugs must be developed to attack these pathways one identified. Presently, there are a wide number of studies investigating both of these steps among a number of cancer types.