Liquid Biopsy May Help Track Changes in Tumors

Liquid Biopsy May Help Track Changes in Tumors

Large study found it predicted when cancer DNA was mutating, could help tailor treatments to avoid drug resistance

WebMD News from HealthDay

By Dennis Thompson

HealthDay Reporter

SATURDAY, June 4, 2016 (HealthDay News) -- Biopsies can be arduous and painful for cancer patients, but necessary to accurately diagnose the disease and determine the best course of treatment.

Now, researchers report that a new blood-based "liquid biopsy" could be a groundbreaking alternative.

Doctors used blood drawn from a patient's arm to analyze DNA that tumors typically shed into the bloodstream, explained lead researcher Philip Mack. He is director of molecular pharmacology at the University of California, Davis, Comprehensive Cancer Center.

A study of more than 15,000 patients with 50 different tumor types determined that liquid biopsy can accurately detect mutations in cancer DNA, Mack said.

"If we saw a mutation in the plasma, that meant it was in the tumor," said Mack, who was to present the findings this weekend at the American Society of Clinical Oncology (ASCO) annual meeting, in Chicago.

Dr. Joshua Brody, director of the Lymphoma Immunotherapy Program at Mount Sinai's Tisch Cancer Institute in New York City, called the research "a big deal. This will be practice-changing."

"This is not quite a Star Trek medical magic wand, but it's getting towards there," Brody said.

However, ASCO Chief Medical Officer Dr. Richard Schilsky noted the study results are encouraging, but do not prove that using a liquid biopsy will result in better patient outcomes.

The research "provides important evidence on the road to proving the clinical utility of liquid biopsies," Schilsky said.

In the study, the researchers used a new genetic scan called Guardant360 that analyzes cancer DNA in patients' blood, looking for mutations in 70 different cancer-related genes. The study received funding from Guardant Health Inc., which produces the test used in the study.

Liquid biopsies provide valuable information for doctors using targeted therapies to treat cancer, Mack said, because they detect when tumors are developing resistance to a particular therapy.

Tumors develop resistance "through the acquisition of new mutations that allow it to circumvent or otherwise ignore a therapeutic option," Mack said. "If we identify what that mutation is, we can treat with a different therapy."

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