Decision is part of UK effort to diagnose 75% of all cancers at stage I or stage II by 2028 and demonstrates to pathologists that the technology used in liquid biopsy tests is improving at a fast pace
Pathologists and medical laboratory scientists know that when it comes to liquid biopsy tests to detect cancer, there is plenty of both hope and hype. Nevertheless, following a successful pilot study at the Christie NHS Foundation Trust in Manchester, England, which ran from 2015-2021, the UK’s National Health Service (NHS) is pushing forward with the use of liquid biopsy tests for certain cancer patients, The Guardian reported.
NHS’ decision to roll out the widespread use of liquid biopsies—a screening tool used to search for cancer cells or pieces of DNA from tumor cells in a blood sample—across the UK is a hopeful sign that ongoing improvements in this diagnostic technology are reaching a point where it may be consistently reliable when used in clinical settings.
The national program provides personalized drug therapies based on the genetic markers found in the blood tests of cancer patients who have solid tumors and are otherwise out of treatment options. The liquid biopsy creates, in essence, a match-making service for patients and clinical trials.
Liquid Biopsy Genetic Testing for Cancer Patients
“The learnings from our original ‘Target’ study in Manchester were that genetic testing needs to be done on a large scale to identify rare genetic mutations and that broader access to medicines through clinical trials being undertaken across the country rather than just one site are required,” Matthew Krebs, PhD, Clinical Senior Lecturer in Experimental Cancer Medicine at the University of Manchester, told The Guardian.
Krebs, an honorary consultant in medical oncology at the Christie NHS Foundation Trust, led the Target National pilot study.
“This study will allow thousands of cancer patients in the UK to access genetic testing via a liquid biopsy. This will enable us to identify rare genetic mutations that in some patients could mean access to life-changing experimental medicines that can provide great treatment responses, where there are otherwise limited or no other treatment options available.”
Detecting cancers at earlier stages of disease—when treatment is more likely to result in improved survival—has become a strategic cancer planning priority in the UK, theBMJ noted.
“The NHS is committed to diagnosing 75% of all cancers at stage I or II by 2028, from around 50% currently,” the BMJ wrote. “Achieving such progress in less than a decade would be highly ambitious, even without disruption caused by the COVID-19 pandemic. In this context, considerable hope has been expressed that blood tests for circulating free DNA—sometimes known as liquid biopsy—could help achieve earlier detection of cancers.”
The Guardian noted that the UK’s initiative will use a liquid biopsy test made by Swiss-healthcare giant Roche.
In her article “The Promise of Liquid Biopsies for Cancer Diagnosis,” published in the American Journal of Managed Care (AJMC) Evidence-based Oncology, serial healthcare entrepreneur and faculty lecturer at Harvard Medical School Liz Kwo, MD, detailed the optimism surrounding the “revolutionary screening tool,” including its potential for:
Welch compared the investor hype surrounding liquid biopsies to that of the now-defunct blood testing company Theranos, which lured high-profile investors to pour millions into its unproven diagnostic technology.
“Effective cancer screening requires more than early detection. It also requires that starting therapy earlier helps people live to older ages than they would if they started treatment later,” he wrote. “If that doesn’t happen, liquid biopsies will only lead to people living longer with the knowledge they have a potentially incurable disease without extending their lives. These people would be subjected to cancer therapies and their toxicities earlier, but at a time when they would otherwise be experiencing no cancer-related signs or symptoms.”
And so, while there’s much excitement about the possibility of a minimally invasive way to detect cancer, anatomic pathology groups and clinical laboratories will have to wait and see if the hype and hope surrounding liquid biopsies is substantiated by further research.
The discovery is yet another factor that must be considered when developing a liquid biopsy test clinical laboratories can use to detect cancer
How often do disruptive elements present in Liquid biopsies result in misdiagnoses and unhelpful drug therapies for cancer? Researchers at the University of Washington School of Medicine (UW Medicine) in Seattle wanted to know. And the results of their study provide another useful insight for pathologists about the elements that circulate in human blood which must be understood so that liquid biopsy tests can be developed that are not affected by that factor.
The UW Medicine researchers advised testing for “variants in the cell-free DNA (cfDNA)” shed in blood plasma to enable appropriate treatment for people with already diagnosed prostate cancer, noted to a UW Medicine news release.
According to pathologist Colin Pritchard, MD, PhD, Associate Professor of Laboratory Medicine and Pathology at the UW Medicine, who led the research team, “clonal hematopoiesis can interfere with liquid biopsies. For example, mutations in the genes BRCA1, BRCA2, and ATM have been closely linked to cancer development.
“The good news is that, by looking at the blood cellular compartment, you can tell with pretty good certainty whether something is cancer, or something is hematopoiesis,” he said in the news release.
What Does CHIP Interference Mean to a Clinical Laboratory Blood Test?
In their published study, the UW Medicine researchers stressed the “urgent need to understand cfDNA testing performance and sources of test interferences” in light of recent US Food and Drug Administration (FDA) clearance of two PARP inhibitors (PARPi) for prostate cancer:
“We found that a strikingly high proportion of DNA repair gene variants in the plasma of patients with advanced prostate cancer are attributable to CHIP,” the researchers wrote. “The CHIP variants were strongly correlated with increased age, and even higher than expected by age group.
“The high rate of CHIP may also be influenced by prior exposure to chemotherapy,” they added. “We are concerned that CHIP interference is causing false-positive cfDNA biomarker assessments that may result in patient harm from inappropriate treatment, and delays in delivering alternative effective treatment options.
“Without performing a whole-blood control, seven of 69 patients (10%) would have been misdiagnosed and incorrectly deemed eligible for PARP-inhibitor therapy based on CHIP interference in plasma. In fact, one patient in this series had a BRCA2 CHIP clone that had been previously reported by a commercial laboratory testing company with the recommendation to use a PARPi. To mitigate these risks, cfDNA results should be compared to results from whole-blood control or tumor tissue,” the researchers concluded.
To find the clinically relevant CHIP interference in prostate cancer cfDNA testing, researchers used the UW-OncoPlex assay (developed and clinically available at UW Medicine). The assay is a multiplexed next-generation sequencing panel aimed at detecting mutations in tumor tissues in more than 350 genes, according to the UW Medicine Laboratory and Pathology website.
“To improve cfDNA assay performance, we developed an approach that simultaneously analyzes plasma and paired whole-blood control samples. Using this paired testing approach, we sought to determine to what degree CHIP interferes with the results of prostate cancer cfDNA testing,” the researchers wrote in JAMA Oncology.
Men May Receive Unhelpful Prostate Cancer Drug Therapies
The research team studied test results from 69 men with advanced prostate cancer. They analyzed patients’ plasma cfDNA and whole-blood control samples.
Tumor sequencing enabled detection of germline (cells relating to preceding cells) variants from CHIP clones.
The UW Medicine study suggested CHIP variants “accounted for almost half of the somatic (non-germline) DNA repair mutations” detected by liquid biopsy, according to the news release.
Other detailed findings of the UW Medicine Study:
CHIP variants of 2% or more were detected in cfDNA from 13 of 69 men.
Seven men, or 10%, having advanced prostate cancer “had CHIP variants in DNA repair genes used to determine PARPi candidacy.
CHIP variants rose with age: 0% in those 40 to 50; 12.5% in men 51 to 60; 6.3% in those 61 to 70; 20.8% in men 71 to 80; and 71% in men 81 to 90.
Whole-blood control made it possible to distinguish prostate cancer variants from CHIP interference variants.
“Men with prostate cancer are at high risk of being misdiagnosed as being eligible for PARPi therapy using current cfDNA tests; assays should use a whole-blood control sample to distinguish CHIP variants from prostate cancer,” the researchers wrote in JAMA Oncology.
“Genetic abnormalities are only one piece of the puzzle. We need to look comprehensively at tumors for the best therapy, from their metabolic changes and protein signatures in the blood to the epigenetic modifications that may occur, as cancers take hold,” he told Oncology Times. “It’s not just shed DNA in the blood.”
The UW Medicine study demonstrates the importance of understanding how all elements in liquid biopsies interact to affect clinical laboratory test results.
“I think liquid biopsies are here to stay,” Cance told Oncology Times. “They’re all part of precision medicine, tailored to the individual.”
Breakthrough assay a ‘tenfold improvement over any prior assay for TERT mutations in the blood for brain tumors,’ MGH says in an affirmation of a diagnostic technology clinical labs might soon use
In recent years, investors have poured tens of millions of dollars into companies that promised to create non-invasive cancer tests which use liquid biopsy technology. Medical laboratory scientists even watched some of these companies hype their particular liquid biopsy tests before clinical studies generated data demonstrating that these tests produced accurate, reliable, and reproducible results.
For diagnosing cancer, a liquid biopsy test typically uses a blood sample with the goal of finding and identifying circulating tumor cells. Harvard Medical School researchers at Massachusetts General Hospital (MGH) believe they have developed just such a blood test. Their assay utilizes an enhanced form of liquid biopsy to detect and monitor one of the more prevalent types of brain tumor in adults—a glioma—and, according to a Harvard news release, can detect the presence of glioma at a significantly higher “overall sensitivity” than other similar liquid-biopsy tests.
Gliomas start in glia cells contained in the brain or spine. They account for about 30% of all brain and central nervous system tumors and 80% of all malignant brain tumors.
During their study, MGH researchers compared blood samples and tumor biopsy tissues from patients diagnosed with a glioma. They discovered that an assay they developed—a droplet digital polymerase chain reaction (ddPCR) blood test—could detect and monitor two types of telomerase reverse transcriptase (TERT) promoter gene mutations—C228T and C250T. These two gene mutations promote cancer growth and are present in more than 60% of all gliomas. The mutations are also present in 80% of all high-grade gliomas, which are the most aggressive and life-threatening types of the cancer.
In the press release, instructor in Neurosurgery at MGH and one of the study’s authors, Leonora Balaj, PhD, said, “By ‘supercharging’ our ddPCR assay with novel technical improvements, we showed for the first time that the most prevalent mutation in malignant gliomas can be detected in blood, opening a new landscape for detection and monitoring of the tumors.”
MGH’s Ten-Fold Improvement over Previous ddPCR Assays
A liquid biopsy is the sampling and analysis of non-solid tissue in the body—primarily blood. MGH’s liquid-biopsy method detects cancer by examining fragments of tumor DNA circulating in the bloodstream. Since the technique is mostly non-invasive, tests can be performed more frequently to track tumors and mutations and monitor treatment progression. Prior to this new method, brain tumors had been difficult to detect using liquid biopsies.
“Liquid biopsy is particularly challenging in brain tumors because mutant DNA is shed into the bloodstream at a much lower level than any other types of tumors,” Balaj said in the press release.
However, MGH’s new ddPCR assay has an overall sensitivity rate of 62.5% and a specificity of 90%, which represents a tenfold improvement over prior assays for TERT mutations in the blood.
And when testing the performance of the ddPCR assay in tumor tissue, the MGH researchers discovered their results were the same as results from a previous independently-performed clinical laboratory assessment of TERT mutations within collected tumor specimens. They also found that their assay could detect TERT mutations when looking at blood plasma samples collected at other facilities.
The researchers believe that their test could be performed in most clinical laboratories and can be utilized to follow the course of disease in cancer patients. The MGH researcher’s goal is to expand and adapt the blood test to diagnose, differentiate, and monitor other types of brain tumors in addition to gliomas.
Of course, more research will be needed before MGH’s new assay can become a vital tool in the fight against disease. However, this type of genetic analysis may soon provide pathologists with new techniques to more accurately diagnose and monitor cancers, and to provide healthcare providers with valuable data regarding which therapies would be the most beneficial for individual patients, a key element of precision medicine.
The researchers unveiled a diagnostic device that uses microfluidic technology to identify cell types in blood by their size. The device also “can isolate individual cancer cells from patient blood samples,” according to a news release.
The ability to isolate circulating tumor cells could enable clinical laboratories to perform diagnostic cancer tests on liquid biopsies and blood samples. Dark Daily reported on various studies involving liquid biopsies—an alternative to invasive and costly cancer diagnostic procedures, such as surgery and tissue biopsies—in previous e-briefings.
The UIC and QUT researchers were motivated by the
information-rich nature of circulating tumor cells. They also saw opportunity
for escalated “purity” in results, as compared to past studies.
In the paper, they acknowledged the work of other scientists
who deployed microfluidic technology affinity-based methods to differentiate
tumor cells in blood. Past studies (including previous work by the authors)
also explored tumor cells based on size and difference from white blood cells.
“While many emerging systems have been tested using patient samples, they share a common shortcoming: their purity remains to be significantly improved. High purity is in strong demand for circulating tumor cell enumeration, molecular characterization, and functional assays with less background intervention from white blood cells,” the authors wrote in their paper.
How the Device Works
The scientists say their system leverages “size-dependent
inertial migration” of cells. According to the news release:
Blood passes through “microchannels” formed in
plastic in the device;
“Inertial migration and shear-induced diffusion”
separate cancer cells from blood;
Tiny differences in size determine a cell’s
attraction to a location; and
Cells separate to column locations as the liquid
In other words, the device works as a filter sorting out, in
blood samples, the circulating tumor cells based on their unique size, New
“A 7.5 milliliter tube of blood, which is typical volume for
a blood draw, might have 10 cancer cells and 35- to 40-billion blood cells. So,
we are really looking for a needle in a haystack,” Papautsky stated in the news
“We report on a novel multi-flow microfluidic system for the
separation of circulating tumor cells with high purity. The microchannel takes
advantage of inertial migration of cells. The lateral migration of cells
strongly depends on cell size in our microchannel, and label-free separation of
circulating tumor cells from white blood cells is thus achieved without
sophisticated sample predation steps and external controls required by
affinity-based and active approaches,” the researchers wrote in their paper.
With so much focus on liquid biopsy research, it may be
possible for medical laboratories to one day not only diagnose cancer through
blood tests, but also to find the disease earlier and in a more precise way
than with traditional tissue sample analysis.
Liquid biopsy tests hold much promise. But inconsistencies in their findings provoke scrutiny and calls from researchers for further development before they can be considered reliable enough for diagnostic use
Many commercial developers of liquid biopsy tests tout the accuracy and benefits of their diagnostic technology. However, there are an equal number of medical laboratory experts who believe that this technology is not yet reliable enough for clinical use. Critics also point out that these tests are being offered as Laboratory Developed Tests (LDTs), which are internally developed and validated and have not undergone regulatory review.
Dark Daily has published several e-briefings on researchers who have sent the same patient samples to different genetic testing labs and received back materially different test results. Now, a new study by Johns Hopkins University concludes that liquid biopsy technology “must improve” before it should be relied upon for diagnostic and treatment decision making.
‘Certification for Medical Laboratories Must Improve’
Liquid Biopsy is the term for drawing whole blood and looking for cancer/tumor cells circulating in the blood stream. This is one factor in the imprecision of a liquid biopsy. Did the blood sample drawn actually have tumor cells? After all, only a limited number of tumor cells, if present, are in circulation.
Gonzalo Torga, MD (above left), and Kenneth J. Pienta, MD (above right), are the two Johns Hopkins Medicine doctors who conducted the recent study into the efficacy of liquid biopsy laboratory developed tests (LDTs) offered by different medical laboratory companies. They published their findings in JAMA Oncology. (Photos copyright: Johns Hopkins.)
In reporting the DNA findings and results from the two medical laboratory companies, researchers discovered that the results completely matched in only three of the 40 patients! The Johns Hopkins researchers are concerned that patients could be prescribed certain cancer treatments based on which lab company’s liquid biopsy test their physician orders, instead of an accurate identification of the unique mutations in their tumors.
“Liquid biopsy is a promising technology, with an exceptional potential to impact our ability to treat patients, but it is a new technology that may need more time and experience to improve,” Gonzalo Torga, MD, Postdoctoral Fellow and Instructor at Johns Hopkins, and the lead author of the study, told Forbes. “We can’t tell from these studies which laboratory’s panel is better, but we can say that certification for these laboratories must improve.”
Unlocking New View of Tumors
Two commercial tests were used for the study:
Guardant360 from Guardant Health, Inc., uses digital sequencing to analyze genomic data points at the single molecular level. It examines 73 genes, including all National Comprehensive Cancer Network (NCCN) listed genes. The test searches for DNA fragments among billions of cells and digitally tags each fragment. This process unlocks a view of tumors that is not seen with tissue biopsies, which helps doctors prescribe the best treatment options for a particular patient.
“As a simple blood test, it provides physicians with a streamlined, cost-effective method to identify genomic alterations that can comprehensively influence a patient’s therapy response,” Helmy Eltoukhy, PhD, co-founder and Chief Executive Officer at Guardant Health, told MDBR.
“The only way of keeping ahead of those diseases and tracking those mutations has been through surgery, through doing a tissue biopsy and physically cutting a piece of the tumor out and sequencing it,” Eltoukhy noted in an interview with Xconomy. “What we’re able to do is essentially get the same, or sometimes better performance to tissue biopsy, but through two teaspoons of blood.”
According to the Guardant Health website, it takes just 14 days for a full report from Guardant360 to reach the ordering physician. In addition, the blood test provides samples with an adequate level of cell-free DNA to test 99.8% of the time and reduces errors and false positives found in standard sequencing methods by 1,000 times. It is common for samples used for tissue sequencing to have insufficient DNA for testing 20% to 40% of the time.
“We believe that conquering cancer is at its core a big data problem, and researchers have been data-starved,” explained Eltoukhy in VentureBeat. “Our launch of the world’s first commercial comprehensive liquid biopsy sparked a boom in cancer data acquisition. Every physician who orders one of our tests, and every patient whose tumor DNA we sequence, adds to this larger mission by improving our understanding of this complex disease.”
PlasmaSELECT-R64, manufactured by Personal Genome Diagnostics (PGDx), evaluates a targeted panel of 64 genes that have biological and functional relevance in making treatment decisions. PGDx announced the expanded version of its PlasmaSELECT assay in March of 2017.
“We are proud to launch the revolutionary PlasmaSELECT 64 expanded assay just six months after we introduced the most accurate, clinically actionable liquid biopsy tumor profiling assay to the market,” said Doug Ward, Chief Executive Officer at PGDx, in a press release. “This update is the first liquid biopsy assay that includes MSI (microsatellite instability) testing as a biomarker for high tumor mutational load, thereby providing cancer patients and their oncologists with information on whether they might be candidates for immuno-oncology therapies. The ability to generate DNA tumor profiling non-invasively using blood or plasma offers many advantages and makes genomic testing more accessible and usable.”
Regulations of LDTs Could be Needed to Improve Liquid Biopsy Tests
There are pathologists and clinical laboratory professionals who believe the technology behind liquid biopsies is not yet reliable enough for clinical use. The tests are being offered as LDTs, which are internally developed and validated, and the Food and Drug Administration (FDA) allows LDTs to be sold without regulatory reviews at this time. However, there are discussions regarding if and how to regulate LDTs, the outcome of which could impact how clinical laboratories are allowed to market the LDTs they develop.
Clearly, liquid biopsies are still in their relatively early stages of development. More testing and evaluation is needed to determine their efficacy. However, their potential to revolutionize cancer detection and care is obvious and a strong motivator for LTD developers, which means there will be future developments worth noting.