Blood-based liquid biopsies have been increasing in use over the past decade, with doctors turning to liquid biopsies to determine how kidney cancer responds to treatment.
An initial cancer diagnosis may consist of a tissue biopsy, which involves invasive methods through endoscopes or open surgery. Tissue biopsies can be painful, risky, and expensive for patients. Liquid biopsies enable oncology doctors to diagnose and monitor cancers non-invasively. They are especially beneficial for repeated sampling for continuous cancer monitoring.
Liquid biopsies are performed by taking a blood sample from a patient and isolating material from the sample such as tumor cells and tumor DNA that may be present in the blood of patients with cancer. This allows doctors to determine if cancer treatments are successful without the need for repeated invasive biopsies of tumors.
A study led by a team of researchers from the University of Wisconsin-Madison tracked over 100 patients who were receiving treatment for renal cell carcinoma (RCC). The research team used liquid biopsies on the patients to determine the number of circulating tumor cells that were present in their blood.
By analyzing changes in the number of tumor cells and their molecular properties in real-time, the researchers could predict the survival rate of a patient while they were undergoing new treatments or receiving additional drug-based treatments for their cancer. For example, patients that were found to have increasing levels of tumor cells in their blood samples lived four months shorter than those with lower rates of tumor cell change in their blood.
“Cancer is not a static disease. As the disease progresses, molecular characteristics change over time, and these changes are important to understand how the disease responds to treatment as well as how resistance develops,” said Matthew Bootsma, a researcher at the UW School of Medicine and Public Health and a lead author of the study. “That makes it really important for a clinician to have real-time access to these metrics.”
Besides their ability to track tumor cells, liquid biopsies can track proteins HLA1 and PD-L1. High levels of HLA1 can cause cells to be more susceptible to attack from the immune system, and high levels of PD-L1 can help tumor cells hide from the immune system. The research team created ratios of HLA1 to PD-L1 for each patient to further track how the ratios changed over the course of treatment. The lower the ratio went, the better their treatments were working. If the ratio went higher or did not change, the researchers determined that this could mean that the tumors were becoming treatment resistant.
The technology behind liquid biopsies is still evolving, but with more research trials, they can soon become the standard of care for determining treatment courses for RCC and other cancers.