Liquid Biopsy Use Can Expand in Cancer Treatment

Liquid biopsies, which are typically used for patients with non-small cell lung cancer (NSCLC), should move into other settings and tumor types, according to Benjamin P. Levy, MD, assistant professor of oncology, clinical director of Medical Oncology, Sidney Kimmel Cancer Center, Johns Hopkins Medicine.

Levy explained that liquid biopsies could be useful in other tumor types; after adjuvant therapy to identify minimal residual disease (MRD) in early-stage lung cancer; and to monitor a tumor’s response after targeted therapy.

“We are just starting to scratch the surface on how to utilize [liquid biopsies]. I am biased, but lung cancer is leading the way and hopefully we will see similar trends in both breast cancer and GI malignancies,” he said in an interview with OncLive, a sister publication of Oncology Nursing News.

Liquid biopsies were initially used to detect T709M when a patient’s lung cancer became resistant to an EGFR-targeted therapy. Now, clinicians are considering using the test alongside tissue testing for all patients with advanced NSCLC.

“Looking at other tumor types, such as gastrointestinal (GI) malignancies and breast cancer, we have also seen some utility [with liquid biopsies]. I do not think some of the utility has been entirely ironed out, as it has been more recently [done] in lung cancer,” Levy said. “We are struggling to use these not only in the stage IV setting for breast cancer and colorectal cancer, but also in the post-curative intent setting to detect MRD.”

For now, tissue biopsies still remain the “gold standard” in many cases, according to Levy, though there are limitations to this kind of testing, such as not being able to get enough tissue, the potential for them to cause complications for patients, and a lengthy turnaround time to get results. These reasons make liquid biopsies an attractive option.

While there are still unanswered questions regarding liquid biopsies, ongoing clinical trials are addressing them.

“There are a lot of trials that are beginning to answer clinically relevant questions in lung cancer with liquid biopsies. We have already learned that there is good concordance between liquid and tissue biopsies from the same patient. A positive test in a plasma sample essentially rules in the genetic alterations. We do not need any more trials looking at concordance,” Levy said.

Where trials are needed, according to Levy, are longitudinal assessment of changes in the ctDNA over time on a therapy, as well as a longitudinal assessment in the post-curative intent setting, testing for MRD.

“The future for liquid biopsies is real-time monitoring a molecular response,” Levy said.

A version of this article originally appeared on OncLive as, “Expert Outlines Next Steps for Liquid Biopsies in Oncology.”