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- Posted Wednesday November 4, 2015
'Liquid biopsy' promotes precision medicine by tracking patient's cancer
Circulating tumor DNA in blood could inform physicians on best treatments for individual patients
PHOENIX, Ariz. - Nov. 4, 2015 - A team of
researchers, including scientists from the Translational
Genomics Research Institute (TGen), has reported that analyzing
circulating tumor DNA (ctDNA) can track how a patient's cancer
evolves and responds to treatment.
In a study published today in Nature Communications, Dr.
Muhammed Murtaza of TGen and Mayo Clinic, and colleagues, describe
an extensive comparison between biopsy results and analysis of
ctDNA in a patient with breast cancer.
The researchers followed the patient over three years of
treatment.
"When patients receive therapy for advanced cancers, not all parts
of the tumor respond equally, but it has been difficult to study
this phenomenon because it is not practical to perform multiple,
repeated tissue biopsies," said Dr. Murtaza, Co-Director of TGen's
Center for Noninvasive Diagnostics, and one of the study's lead
authors.
"Our findings empirically show that ctDNA analysis from blood
samples allows us to detect cancer mutations from multiple
different tumor sites within a patient and track how each of them
responds," Dr. Murtaza said.
This type of blood test - known as a liquid biopsy - is less
invasive, less costly and less risky than conventional tissue
biopsies, which essentially are minor surgeries. Obtaining liquid
biopsies could occur more frequently, too, thus providing
physicians with up-to-date information about how a patient's cancer
might be changing. This, in turn, could help in the selection of
the best possible treatments to combat the cancer.
The researchers followed a 42-year-old woman diagnosed with
invasive ductal carcinoma -the most common type of breast
cancer- that had spread to other parts of her body, including
her backbone, chest and liver. Eventually, it spread to her brain
and left ovary.
Over the course of her illness, the researchers obtained eight
tissue biopsies and nine blood samples for study, including samples
obtained at a research autopsy. Their analysis revealed that ctDNA
in blood samples tracked mutations that occurred in her cancer as
it spread to various parts of her body and identified the tumor
sites that developed resistance to therapy.
"Our results show that ctDNA, collected through liquid biopsies,
provides a dynamic sampling of cancer cell alterations, reflecting
the size and activity of distinct parts of the tumor," Dr. Murtaza
said.
Further, the study results suggest that precise and up-to-date
genetic monitoring of changes in a patient's cancer, through ctDNA
analysis, could help inform physicians what type of targeted
treatment might be best at each stage of the disease.
"The potential of using circulating DNA for estimating just how
well a patient may respond to targeted therapies and for tracking
the development of resistant clones in real-time, heralds a new era
for precision medicine," said Dr. A. Keith Stewart, Carlson and
Nelson Endowed Director, Mayo Clinic Center for Individualized
Medicine. Dr. Stewart was not involved in the research.
While the study, Multifocal clonal evolution characterized
using circulating tumor DNA in a case of metastatic breast
cancer, resulted from deep genomic analysis of a single
patient, the observations have important implications for future
ctDNA studies.
Contributing to and supporting this study were: Mayo Clinic in
Arizona, the University of Cambridge, the Human Research Tissue
Bank at Addenbrooke's Hospital, the NIHR Cambridge Biomedical
Research Centre, Cancer Research UK, National Institute for Health
Research Cambridge Biomedical Research Centre, Cambridge
Experimental Cancer Medicine Centre, Illumina Inc., Peter MacCallum
Cancer Centre, the Australian National Breast Cancer Foundation and
Victorian Cancer Agency Early Career Fellowship, and Science
Foundation Arizona's Bisgrove Scholars Early Tenure Track
Award.
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About TGen
Translational Genomics Research Institute (TGen) is a Phoenix,
Arizona-based non-profit organization dedicated to conducting
groundbreaking research with life changing results. TGen is focused
on helping patients with neurological disorders, cancer, and
diabetes, through cutting edge translational research (the process
of rapidly moving research towards patient benefit). TGen
physicians and scientists work to unravel the genetic components of
both common and rare complex diseases in adults and children.
Working with collaborators in the scientific and medical
communities literally worldwide, TGen makes a substantial
contribution to help our patients through efficiency and
effectiveness of the translational process. For more information,
visit:www.tgen.org. Follow TGen on Facebook, LinkedIn and Twitter @TGen.
Press Contact:
Steve Yozwiak
TGen Senior Science Writer
602-343-8704
[email protected]
About Mayo Clinic
Mayo Clinic is a nonprofit organization committed to medical
research and education, and providing expert, whole-person care to
everyone who needs healing. For more information, visit http://www.mayoclinic.org/about-mayo-clinic or
http://newsnetwork.mayoclinic.org.