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Duke doctors discover key cancer predictor

An easily detectable enzyme in metastatic kidney cancer patients allows doctors to more effectively treat patients.

Doctors at the Duke Cancer Institute discovered a common enzyme that can dictate the course of treatment for patients with high-risk kidney cancer. These findings, published Aug. 13 in the Journal of Clinical Oncology, show how using biomarkers—predictors for how the body will react to various courses of treatment—can spare patients from treatment that may not be beneficial for their particular type of cancer.

“Kidney cancer is making more progress than any other tumor type [and] we need to move this kind of work forward with other biomarkers,” said Dr. Andrew Armstrong, assistant professor of medicine and surgery and lead author of the study.

High levels of the enzyme lactate dehydrogenase, or LDH, indicates the creation of abnormally high levels of a protein commonly known as mTOR, which have traditionally been identified as a risk factor for tumor progression, Armstrong said. The findings, however, show that high levels of LDH in a patient’s blood can actually predict the best combination of drugs.

For example, metastatic kidney cancer patients with high-levels of LDH may benefit from drugs called mTOR inhibitors, whereas ones with normal levels of LDH would not benefit from such drugs, he said.

“We have seven drugs that are now approved for kidney cancer [patients]…that’s already a lot of choices,” Armstrong said. “So any more information that you can use on top of what we already have is really helpful.”

Armstrong noted that whenever he gets a patient with metastatic kidney cancer he tries to identify the best therapy for that particular individual, but prior to the study there was no biomarker for kidney cancer that could determine the appropriate course of treatment for the patient. These findings could lead to the first ever blood test to determine the best treatment for metastatic kidney cancer.

Because the study looked at high-risk patients, however, it’s hard to evaluate whether the new findings help patients in the long-run, said Dr. Daniel George, the director of genitourinary medical oncology and co-author of the study.

“We are characterizing patients who are at higher risks for disease progression and early death better than we have in the past,” he said. “It’ll take more clinical trials to see how much of a survival benefit that is, but anytime we can more accurately help patients understand their prognosis and specifically how to manage that prognosis, well, that puts us at an advantage.”

George added that the blood test that measures a patient’s LDH level is already a routine procedure that is cheap and easy to get, making the study’s findings a feasible addition to kidney cancer treatment.

The discovery of this particular biomarker could lead other medical professionals to find biomarkers for other types of cancers, George said, adding that if it is possible to identify drugs based on a patient’s LDH level, then there must be other biomarkers to identify drugs for other types of kidney cancer or different tumors in general.

“This is a really encouraging result—we are understanding the predictor of this disease to respond to certain therapies that have real relevance to the biology of the [cancer],” he said. “It is important to see what predictive value this biomarker has in other cancers.”

Because the biomarker allows scientists to further understand the biology of metastatic kidney cancer, medical professionals can continue to decipher the most effective combination of therapies for their patients, George said.

“The goal is to get a cure,” he said. “[mTOR inhibitors] do not get us the cure, but if we can use this drug and build on our findings… we can hope to get the right combination of therapies that can get us the cure.”

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