Liquid biopsy helps Mayo researchers identify ovarian cancer recurrence faster

Mayo Clinic researchers have found liquid biopsy is an effective way to monitor and treat ovarian cancer recurrence faster. When combined with DNA sequencing, liquid biopsy can detect a return of the cancer long before a tumor reappears.

Investigators led by George Vasmatzis, Ph.D. (HSR ’99), co-director of the Biomarker Discovery Program in the Center for Individualized Medicine and consultant in the Department of Molecular Medicine, compared DNA from liquid biopsies to DNA tissue samples from tumors in 10 patients with advanced ovarian cancer, using mate-pair sequencing, which can reveal genetic changes that contribute to tumor growth.

“The blood drawn before and after surgery and the surgical tissue were used to identify DNA fragments with abnormal junctions that can only be seen in the patients’ tumors DNA,” says Dr. Vasmatzis. “We used next-generation mate-pair sequencing to identify specific DNA changes of a tumor to create an individualized monitoring panel for liquid biopsy. This allows us to tailor treatment to the patient instead of using a standard treatment that may not work for everyone.”

When post-surgery DNA matched that of the tumor, patients were later found to have had a recurrence of ovarian cancer. When the post-surgery DNA did not match the DNA of the tumor, patients were found to be in remission.

“We don’t have to wait for tumor growth to get a DNA sample,” says Dr. Vasmatzis. “The hope is to detect disease recurrence earlier than other diagnostic methods. And we can repeat noninvasive liquid biopsies over time to monitor disease progression. Earlier intervention and more effective, individualized treatment will be possible with this approach.”

This new approach is not yet in clinical practice.

Dr. Vasmatzis estimates it will take two years before that happens. At that time, the approach will be applicable to any type of cancer.

“We studied ovarian cancer first because we thought it would have the most tumor DNA in the blood,” he says. “This approach is most useful in more aggressive cancers. We’re also studying sarcoma and prostate cancer.

“This isn’t early detection. This approach requires the tumor tissue to identify the tumor DNA junctions. However, some Mayo Clinic researchers are working on using liquid biopsy for early detection. A very small number of cancers, including pancreatic, have a mutation that could be detected earlier in blood. Our approach is particularly useful after a patient has had surgery to remove cancer – Did the surgery work? Is there residual disease left behind? And when there is, we can treat it earlier than we otherwise would be able to.”

This research was published in July 20, 2016, Scientific Reports.