A common enzyme easily detected in blood may predict how well patients with advanced kidney cancer will respond to a specific treatment, according to doctors at Duke Cancer Institute. The finding, published online in the Journal of Clinical Oncology, could lead to the first blood test to determine best treatment for late-stage kidney cancer.
The researchers focused on an enzyme known as lactate dehydrogenase, or LDH, found in almost all body tissues, which plays a role in converting food to energy. As cells die or are injured, they release LDH, so elevated LDH levels have long been used to identify cancer, tissue damage, and other disorders.
In kidney cancer, elevated LDH levels have been considered a signal of tumor progression. Recent studies have suggested that elevated LDH may indicate the activation of key genetic alterations that lead to cancer proliferation. One of these cancer gene pathways relies on a protein called mammalian target of rapamycin, or mTOR. Drugs called mTOR inhibitors work to shut down the process.
An international Phase III trial testing an mTOR inhibitor known as temsirolimus found that the then-investigational drug extended the lives of patients with kidney cancer that had spread to other areas of the body. Intrigued by those results, researchers used data from the trial to determine whether a high LDH level was more than just a prognostic tool in advanced kidney cancer, and could perhaps also predict the effectiveness of an mTOR inhibitor. They found that patients with high LDH levels survived significantly longer on the mTOR inhibitor drug than they did on interferon-alpha. Patients with low LDH showed little difference in survival based on the drug they received.
