Liquid Biopsies Offer New Hope for Treatment and Tracking of Ovarian Cancer

OC tumors often cannot be detected until the late stages. Most patients go into remission after initial treatment, but the tumor returns 75% of the time and returning OC tumors typically do not respond to chemotherapy.

The research was performed by a Mayo Clinic (Rochester, MN, USA) team led by George Vasmatzis, PhD, Department of Laboratory Medicine and Pathology. “With liquid biopsies, we don’t have to wait for tumor growth to get a DNA sample,” said Dr. Vasmatzis, “This important discovery makes it possible for us to detect recurrence of the disease earlier than other diagnostic methods. We can repeat liquid biopsies to monitor the progression of the cancer.”

The study was done on 10 patients in advanced stages of OC, comparing DNA from the liquid blood biopsies to tumor tissue DNA samples. Mate-pair sequencing, an inexpensive whole-exome sequencing that can reveal genetic changes that contribute to tumor growth, was used.

“In this study, the blood drawn before and after surgery and the surgical tissue was used to identify DNA fragments with abnormal [chromosomal] junctions that can only be seen in this patient’s tumor DNA,” explained Dr. Vasmatzis, “Next-generation mate-pair sequencing was used to identify specific DNA changes of the tumor to create an individualized monitoring panel for liquid biopsy. This allows us to shape treatment to the individual patient rather than using a standard treatment that may not work for everyone.”

Individualized tumor-specific primer panels of aberrant chromosomal junctions were identified for each case and detected by qPCR within the cell-free DNA (cfDNA). When post-surgery DNA matched that of the tumor (circulating tumor DNA [ctDNA]), patients were later found to have had a recurrence of OC. However, when the post-surgery DNA did not match the DNA of the tumor, patients were found to be in remission. The findings suggest that a primer panel for individualized chromosomal junctions derived from tumor DNA could be effective for monitoring cancer patients for relapse and therapeutic efficacy using cfDNA.

The study, by Harris FR et al, was published July 20, 2016, in the journal Scientific Reports.

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