All cancers are not created equal.
That’s the idea behind a growing body of international research, led in part by City of Hope scientists. They’re uncovering individual differences in patients’ cancers — at the molecular level — and revealing how those differences can affect treatment success.
Compare two patients, for example. Both have the same type of colon cancer at the same stage. But the genetics of their tumors may be different. By taking a genetic fingerprint of each patient’s tumor, a physician may be able to predict which treatments will work best for each of them. The doctor then could prescribe customized treatment plans offering a greater chance of success.
Learning more about the mechanisms behind cancer also points scientists to targets for developing smarter drugs.
Leaders in the field
At City of Hope, one of the leaders of the personalized medicine movement is Yun Yen, M.D., Ph.D., Dr. & Mrs. Allen Y. Chao Chair in Developmental Cancer Therapeutics and chair of the Department of Molecular Pharmacology.
Yen and his colleagues are studying how an enzyme called RR — short for ribonucleotide reductase — contributes to cancer development and spread.
In a recent study, Yen’s team showed that patients with advanced colorectal tumors that had high levels of a certain subunit of RR, called RRM2B, survived longer and had better outcomes after treatment, for example.
Their analysis of more than 300 tumors from patients uncovered evidence that tumors making more RRM2B were less likely than other tumors to invade surrounding tissue or spread to lymph nodes.
The findings suggest that RRM2B might help physicians predict how well a given patient will do following treatment for colorectal cancer, Yen said. Eventually, physicians might be able to test a patient’s tumor for levels of RRM2B and choose a therapy based on the results.
These findings follow closely on another success from Yen’s team: They found that levels of another protein, called HMGA2, also corresponded to colorectal cancer patients’ survival.
Results into action
In colorectal cancer, personalized medicine has reached the clinic. Doctors can test patients to see if their tumors harbor a mutated form of a protein called Kras. About 20 to 50 percent of colorectal cancers do, and those tumors respond poorly to certain drugs.
So doctors use different treatments for patients with mutated Kras right from the start. This avoids unnecessary side effects and provides a therapy that is more likely to work.
Scientists offer a similar test for nonsmall cell lung cancer. (Both this test and the Kras test are available through City of Hope’s Molecular Diagnostic Laboratory.)
One private firm offers a test for nearly two dozen genetic markers that can predict whether breast or colon cancer will return. Physicians are evaluating these tests to see how best to incorporate them into treatment decision-making.
“We are enthusiastic about the potential of different biomarkers to improve therapy,” said Yen. “Not only may they help in terms of making treatment decisions, but they help us understand how cancers work. And that may lead to new therapies, as well.”