Liquid Biopsy Tracks Herceptin Resistance in HER2+ Gastric Cancer


Liquid biopsy of circulating tumor DNA (ctDNA) is an “efficient” way to monitor resistance to trastuzumab (Herceptin, Genentech) and spot emerging resistance mechanisms in metastatic human epidermal growth factor receptor 2 (HER2)-positive gastric cancer, according to a study from China.

Up to 23% of gastric cancers are HER2+, but the response rate of these tumors to trastuzumab is limited, and any resistance to the drug happens rapidly during treatment, De-Shen Wang, MD, PhD, Department of Medical Oncology, Sun Yat-sen University Cancer Center, Guangzhou, China, told Medscape Medical News.

“Currently, the underlying mechanism of trastuzumab resistance remains unclear, and strategies to overcome resistance are urgently needed,” said Wang.

“We found that liquid biopsy-based ctDNA profiling could promisingly predict the tumor shrinkage and progression, and the underlying mechanism for innate resistance and acquired resistance of Herceptin might be different due to the differences of observed HER2 copy numbers,” Wang added.

The study was published online in the journal Gut.

Researchers evaluated the consistency between molecular alterations in solid tumor biopsies and liquid (plasma) biopsies by sequencing a panel of 416 cancer-related genes from 78 patients with gastric cancer (46 HER2+ and 32 HER2–). They also performed longitudinal analyses of 97 serial plasma samples collected from 24 patients who were HER2+ to track resistance during trastuzumab treatment and validate candidate resistance genes identified.

The molecular alterations detected in plasma provided a “good representation of the status of the tumor tissue, particularly at advanced stages,” the authors report in their article.

HER2 somatic copy number alterations (SCNA) were “highly consistent” with fluorescence in situ hybridization data, and the detected HER2 copy number variation was better than the plasma carcinoembryonic antigen level at predicting tumor shrinkage and progression, they note.

Most patients with innate trastuzumab resistance had high HER2 SCNA during progression compared with baseline, while HER2 SCNA decreased in patients with acquired resistance, they found.

PIK3CA/R1/C3 or ERBB2/4 mutations contributed “greatly” to resistance and led to worse progression free survival, whereas ERBB4 S774G mutation increased sensitivity to trastuzumab, Wang said.

The researchers also identified and confirmed NF1 as a resistance-related gene and found evidence that the combination of the HER2 inhibitor lapatinib (Tykerb, GlaxoSmithKline) and MEK/ERK inhibitor selumetinib (AstraZeneca) might overcome trastuzumab resistance.

“We propose that ctDNA profiling could provide helpful information to monitor the occurrence, dissect the potential molecular mechanisms, and provide helpful clues to therapy development for Herceptin resistance,” Wang told Medscape Medical News.

However, the technique, and this study, has several limitations, the authors note. First, although the 416-gene panel covered the majority of solid tumor-related genes, patients might have developed a mutation in a gene not covered by the panel. It’s also possible that the function of a protein encoded by a certain gene was regulated at the transcriptional, translational, or even post-translational level, and thus was not detected by DNA sequencing, they explain.

Second, they note that cell-free DNA (cfDNA) from plasma contains both cfDNA released from normal cells and ctDNA from limited tumor cells, leading to a lower tumor DNA content in the whole plasma cfDNA sample in most cases, which generates large amounts of “noise” and limits ctDNA detection sensitivity.

“A higher sequencing coverage depth might improve the detection sensitivity of ctDNA profiling to a certain extent but would not completely solve the problem due to the limited number of original tumor DNA molecules present in the cfDNA sample,” the authors suggest.

Liquid Biopsy Is Effective at Guiding Treatment of Lung Cancer, Study Finds


A tube of blood superimposed on a lung and a DNA helix

Summary

For people with lung cancer, a blood test known as a liquid biopsy can be a useful tool for guiding treatment decisions, according to a new study from researchers at Memorial Sloan Kettering, the University of Sydney, and a biotech company called Resolution Bioscience.

Doctors and patients alike have cheered the arrival of liquid biopsies to modern cancer medicine.

These high-tech tests measure infinitesimally small amounts of DNA that is shed from tumor cells and is circulating in the blood. The tests can provide doctors with information about which mutations are present in a person’s cancer, without needing to perform a surgical biopsy. Several are commercially available.

While much touted, liquid biopsies have yet to really prove their mettle when it comes to improving patient care.

“We still don’t have good evidence showing whether and how a liquid biopsy can help people who are struggling with cancer today,” says Bob Li, a medical oncologist at Memorial Sloan Kettering who specializes in the treatment of people with lung cancer. “There is an urgent need to demonstrate not only the scientific validity of the test but also its clinical utility — how it can help patients.”

That’s why, two years ago, Dr. Li and his colleagues began a prospective clinical study to evaluate whether a liquid biopsy test could help guide treatment decisions for people with lung cancer. The initial results of the ongoing study were published on November 28 in the Journal of the National Cancer Institute. The authors conclude that liquid biopsy–guided treatment is “feasible, rapid, and useful.”

Details of the Study

The paper covers the first 210 patients enrolled in the study. They all had advanced-stage non-small cell lung cancer that either had no known mutation that could be targeted with a drug or had stopped responding to a targeted therapy. Their cancers had spread beyond the primary location.

Each patient had the liquid biopsy test performed on a blood sample. About half of the patients (106) also had their tumor tissue genetically sequenced by MSK’s DNA-sequencing platform, called MSK-IMPACT™.

Among the most important benefits of the liquid biopsy was the quick turnaround time. It took a median of nine days from the time of the blood draw for doctors to get the results of the liquid biopsy. It takes a median of 20 days from the time a tissue specimen arrives in a lab to get results from tumor sequencing.

If I see that a patient has a liquid biopsy result that is positive … I’m confident that I can match the patient to a therapy and treat that patient immediately.
Bob T. Li
Bob T. Li medical oncologist

Given that people with late-stage lung cancer can be quite sick, that time difference can be significant.

“The overall health of a person suffering from advanced-stage lung cancer can deteriorate very rapidly in the space of a couple of weeks,” Dr. Li says. “Sometimes if you wait too long, you’ve missed the boat, so to speak, for effective treatment.”

But if a liquid biopsy turns up a targetable mutation, doctors can act on it right away.

In the study, just over 45% of the patients were found by liquid biopsy to have a mutation that could be targeted by an approved or investigational drug. About 22% of the patients (46 people) received one such drug, and nearly all of them experienced a benefit — namely, a decrease in the size of their tumors.

What the Liquid Biopsy Measures

The particular liquid biopsy test used in this study is made by Resolution Bioscience, a biotech company based in Redmond, Washington. It looks for mutations in 21 genes that are known to be involved in non-small cell lung cancer.

By comparing the results of the liquid biopsy to those of tumor tissue, the team determined that the overall concordance rate between the two approaches was 56.6%. This means that for a little more than half of the people, both tests identified at least one mutation in common.

What cheered the team more was that when they looked just at people who tested positive for a cancer mutation on the liquid biopsy, 89.6% had that same mutation also identified by the test of tumor tissue. Finally, when the investigators looked at only patients with driver mutations found on the liquid biopsy — those that matter most in terms of treatment — the rate of agreement between the two tests was 96.1%.

“If I see that a patient has a liquid biopsy result that is positive, especially for a driver mutation, I’m confident that I can match the patient to a therapy and treat that patient immediately without waiting for the tissue results,” Dr. Li says.

One major caveat, he notes, is that a negative result on a liquid biopsy does not mean that a person has no targetable mutations. In that case, the person would need to have a tissue biopsy to look for a targetable mutation.

 

More than an Academic Pursuit

MSK, the University of Sydney, and Resolution Bioscience are academic collaborators on this study, and there is no exchange of money between them. Resolution Bioscience covers the costs associated with the test for all enrolled patients, and neither MSK nor the University of Sydney charges Resolution Bioscience for access to patients’ blood. Patients who consent to the study receive the liquid biopsy free of charge.

For Dr. Li, the results of the study are much more than a narrow academic concern. People’s lives depend on it.

He gives the example of a patient who was misdiagnosed at another hospital before coming to MSK. “This previously healthy young man was so sick with widespread metastases, he had lost 30 pounds,” Dr. Li recalls.

He ordered a liquid biopsy, and within days it showed that his patient had a targetable mutation. Dr. Li quickly started him on a matched drug.

“The patient immediately felt better,” he says. “This was about a year ago, and now he’s playing basketball and is back to work. He’s quite excited about the results of this study as well.”

Dr. Li suggests that patients talk to their doctor about whether a liquid biopsy might help direct or improve their treatment.

“We’re very pleased that our study showed the value of a liquid biopsy. We hope that such tests will eventually become an integral part of care to help many more patients,” he says.

‘Liquid Biopsy’ May Show Whether Cancer Drugs Are Working


Researchers have developed a blood test that might allow doctors to know quickly whether a cancer drug is working.

The technique is in the early stages of testing, and not ready for “prime time,” scientists said. But they were also hopeful that the research will help advance the use of so-called liquid biopsies in treating cancer.

Doctors have long used invasive biopsy procedures to get tumor samples, study them, then use the information to make treatment decisions or monitor a patient’s response to treatment.

But those procedures can be uncomfortable and carry some risks, like bleeding and infection, said Dr. Erica Mayer, a breast cancer expert with the American Society of Clinical Oncology (ASCO).

Plus, she noted, some tumors are difficult to reach, and some patients are not healthy enough to have an invasive biopsy.

So there’s been “great interest,” Mayer said, in liquid biopsy technology — which allows doctors to detect and analyze tumor DNA in a blood sample.

“It’s much more favorable for patients because it doesn’t have the potential risks of traditional biopsies,” Mayer said. It’s also easier for doctors to take repeat blood samples over time.

There are already some liquid biopsy tests on the market. Last month, the U.S. Food and Drug Administration approved the first such test that can detect particular gene mutations that affect some lung cancer patients. If they carry the mutations — in a gene called EGFR — then they may benefit from the cancer drug Tarceva.

Also last month, a large study presented at ASCO’s annual meeting reported that liquid biopsies can be a reliable alternative to traditional biopsies when it comes to detecting mutations in patients’ cancer.

That study focused on finding tumor mutations that can be targeted with available drugs, said senior researcher Chwee Teck Lim.

“For our [test], we go one step further, to see how a patient’s cancer cells will actually respond to a given drug treatment,” explained Lim, a professor of biomedical engineering at National University of Singapore.

The technique involves using “microwells” to grow clusters of tumor cells from a patient’s blood sample. Lim’s team tested the approach using blood samples from 55 women in various breast cancer treatment trials.

They exposed the women’s tumor cells to a standard cancer drug called doxorubicin and found that the better the cell clusters established themselves in the microwells, the worse a patient’s prognosis.

The technique could give feedback as quickly as two weeks after treatment has begun, the researchers report online July 13 in the journal Science Advances.

That, Lim said, means that doctors could get “crucial information” on whether a patient’s cancer is responsive or resistant to a drug — and then make a switch if needed.

But, he stressed, this was only a “proof-of-concept” study. He said his team is planning to see how the test performs when other cancer drugs, and other types of tumors, are used.

Liquid biopsies are part of the wider drive toward more “individualized therapy” for cancer, said Mayer, a medical oncologist at the Dana-Farber Cancer Institute, in Boston.

More and more “targeted” drugs are being developed, with the aim of zeroing in on specific abnormal proteins on cancer cells. Liquid biopsies are seen as a simpler, less invasive way to find out whether patients have mutations that are vulnerable to those drugs.

But the biopsies can also be used in other ways, Lim said. That includes monitoring a patient’s response to treatment.

“The rapid feedback provided by this [test] potentially allows detection of an onset of drug tolerance or resistance during the course of treatment,” Lim said. “This will enable us to immediately intervene and change treatment.”

It’s “premature,” Mayer said, to speculate on whether or how this test could eventually fit into cancer care.

For one, she noted, “what researchers see in a lab dish may not reflect what’s going on in a living being.”

But in general, Mayer said, the work being done on liquid biopsy technology is “exciting and promising.”

Liquid biopsy-based clinical research in early breast cancer


Highlights

This study evaluates the concept of targeting minimal residual disease (presence of circulating tumour cells).

Liquid-based biopsy clinical research is feasible.

This is the first study of its kind in adjuvant therapy of breast cancer.


Abstract

There is increasing evidence that breast cancer evolves over time under the selection pressure of systemic treatment. Today, treatment decisions in early breast cancer are based on primary tumour characteristics without considering the disease evolution. Chemoresistant micrometastatic disease is poorly characterised and thus it is not used in current clinical practice as a tool to personalise treatment approaches. The detection of chemoresistant circulating tumour cells (CTCs) has been shown to be associated with worse prognosis in early breast cancer. The ongoing Treat CTC trial is the first international, liquid biopsy-based trial evaluating the concept of targeting chemoresistant minimal residual disease: detection of CTCs following adjuvant chemotherapy (adjuvant cohort) or neoadjuvant chemotherapy in patients who did not achieve pathological complete response (neoadjuvant cohort). This article presents the rational and design of this trial and the results of the pilot phase after 350 patients have been screened and provides insights that might provide information for future trials using the liquid biopsy approach as a tool towards precision medicine

‘Liquid biopsy’ blood test accurately detects key genetic mutations in most common form of lung cancer, study finds


A simple blood test can rapidly and accurately detect mutations in two key genes in non-small cell lung tumors, researchers at Dana-Farber Cancer Institute and other institutions report in a new study – demonstrating the test’s potential as a clinical tool for identifying patients who can benefit from drugs targeting those mutations.

The test, known as a liquid biopsy, proved so reliable in the study that Dana-Farber/Brigham and Women’s Cancer Center (DF/BWCC) expects to offer it soon to all patients with non-small cell lung cancer (NSCLC), either at the time of first diagnosis or of relapse following previous treatment.

NSCLC is the most common form of lung cancer, diagnosed in more than 200,000 people in the United States each year, according to the American Cancer Society. An estimated 30 percent of NSCLC patients have mutations in either of the genes included in the study, and can often be treated with targeted therapies. The study is being published online today by the journal JAMA Oncology.

The liquid biopsy tested in the study – technically known as rapid plasma genotyping – involves taking a test tube-full of blood, which contains free-floating DNA from cancer cells, and analyzing that DNA for mutations or other abnormalities. (When tumor cells die, their DNA spills into the bloodstream, where it’s known as cell-free DNA.) The technique, which provides a “snapshot” of key genetic irregularities in a tumor, is a common tool in research for probing the molecular make-up of different kinds of cancers.

“We see plasma genotyping as having enormous potential as a clinical test, or assay – a rapid, noninvasive way of screening a cancer for common genetic fingerprints, while avoiding the challenges of traditional invasive biopsies,” said the senior author of the study, Geoffrey Oxnard, MD, thoracic oncologist and lung cancer researcher at Dana-Farber and Brigham and Women’s Hospital. “Our study was the first to demonstrate prospectively that a liquid biopsy technique can be a practical tool for making treatment decisions in cancer patients. The trial was such a success that we are transitioning the assay into a clinical test for lung cancer patients at DF/BWCC.”

The study involved 180 patients with NSCLC, 120 of whom were newly diagnosed, and 60 of whom had become resistant to a previous treatment, allowing the disease to recur. Participants’ cell-free DNA was tested for mutations in the EGFR and KRAS genes, and for a separate mutation in EGFR that allows tumor cells to become resistant to front-line targeted drugs. The test was performed with a technique known as droplet digital polymerase chain reaction (ddPCR), which counts the individual letters of the genetic code in cell-free DNA to determine if specific mutations are present. Each participant also underwent a conventional tissue biopsy to test for the same mutations. The results of the liquid biopsies were then compared to those of the tissue biopsies.

The data showed that liquid biopsies returned results much more quickly. The median turnaround time for liquid biopsies was three days, compared to 12 days for tissue biopsies in newly diagnosed patients and 27 days in drug-resistant patients.

Liquid biopsy was also found to be highly accurate. In newly diagnosed patients, the “predictive value” of plasma ddPCR was 100 percent for the primary EGFR mutation and the KRAS mutation – meaning that a patient who tested positive for either mutation was certain to have that mutation in his or her tumor. For patients with the EGFR resistance mutation, the predictive value of the ddPCR test was 79 percent, suggesting the blood test was able to find additional cases with the mutation that were missed using standard biopsies.

“In some patients with the EGFR resistance mutation, ddPCR detected mutations missed by standard tissue biopsy,” Oxnard remarked. “A resistant tumor is inherently made up of multiple subsets of cells, some of which carry different patterns of genetic mutations. A single biopsy is only analyzing a single part of the tumor, and may miss a mutation present elsewhere in the body. A liquid biopsy, in contrast, may better reflect the distribution of mutations in the tumor as a whole.”

When ddPCR failed to detect these mutations, the cause was less clear-cut, Oxnard says. It could indicate that the tumor cells don’t carry the mutations or, alternatively, that the tumor isn’t shedding its DNA into the bloodstream. This discrepancy between the test results and the presence of mutations was less common in patients whose cancer had metastasized to multiple sites in the body, researchers found.

The ddPCR-based test, or assay, was piloted and optimized for patients at the Translational Resarch lab of the Belfer Center for Applied Cancer Science at Dana-Farber. It was then validated for clinical use at Dana-Farber’s Lowe Center for Thoracic Oncology.

An advantage of this form of liquid biopsy is that it can help doctors quickly determine whether a patient is responding to therapy. Fifty participants in the study had repeat testing done after starting treatment for their cancer. “Those whose blood tests showed a disappearance of the mutations within two weeks were more likely to stay on the treatment than patients who didn’t see such a reduction,” said the study’s lead author, Adrian Sacher, MD, of Dana-Farber and Brigham and Women’s Hospital.

And because tumors are constantly evolving and acquiring additional mutations, repeated liquid biopsies can provide early detection of a new mutation – such as the EGFR resistance mutation – that can potentially be treated with targeted agents.

“The study data are compelling,” said DF/BWCC pathologist Lynette Sholl, MD, explaining the center’s decision to begin offering ddPCR-based liquid biopsy to all lung cancer patients. “We validated the authors’ findings by cross-comparing results from liquid and tissue biopsies in 34 NSCLC patients. To work as a real-world clinical test, liquid biopsy needs to provide reliable, accurate data and be logistically practical. That’s what we’ve seen with the ddPCR-based blood test.

“The test has great utility both for patients newly diagnosed with NSCLC and for those with a recurrence of the disease,” she continued. “It’s fast, it’s quantitative (it indicates the amount of mutant DNA in a sample), and it can be readily employed at a cancer treatment center.”

The Liquid Biopsy: A Noninvasive Tumor Tracker.


To date, the “liquid biopsy,” a blood test that detects evidence of cancer in the circulation, has generated a lot of excitement in the lab but little in the clinic.

The only liquid biopsy currently approved by the US Food and Drug Administration (FDA) for clinical use is a prognostic survival tool with no potential to guide treatment decisions (CellSearch, Janssen Diagnostics).

But research published in the February 19 issue of Science Translational Medicine shows how liquid biopsies can provide a noninvasive, ongoing picture of a patient’s cancer, offering valuable insight into how best to fight it.

Work from 2 different groups shows how liquid biopsies are being used in the lab to identify tumors at a very early stage, monitor them for metastasis, and even pick up signs of early treatment resistance.

In the future, instead of extensive imaging and invasive tissue biopsies, liquid biopsies could be used to guide cancer treatment decisions and perhaps even screen for tumors that are not yet visible on imaging.

“I think early detection is the Holy Grail of cancer research,” said Luis Diaz Jr., MD, from Johns Hopkins University School of Medicine in Baltimore. Liquid biopsies will likely offer a screening method for most cancers one day, he told Medscape Medical News.

However, this exciting potential is probably furthest from being ready for the clinic, he acknowledged; other potential applications include genotyping, detection of minimal residual disease, and detection of treatment resistance.

In their research, Dr. Diaz and colleagues show that a liquid biopsy measuring the serum level of circulating tumor (ct)DNA could one day be a very useful tool in cancer decision-making, giving clues about what type of cancer a patient has and whether it has spread.

“Mutant DNA fragments are found at relatively high concentrations in the circulation of most patients with metastatic cancer and at lower but detectable concentrations in a substantial fraction of patients with localized cancers,” they write.

The team found this to be particularly true in cases of breast, colon, pancreas, and gastroesophageal tumors, where “detectable levels of ctDNA were present in 49% to 78% of patients with localized tumors and 86% to 100% of patients with metastatic tumors.”

They evaluated 136 metastatic tumors in 14 different tumor types, and found that “most patients with stage III ovarian and liver cancers and metastatic cancers of the pancreas, bladder, colon, stomach, breast, liver, esophagus, and head and neck, as well as neuroblastoma and melanoma, harbored detectable levels of ctDNA. In contrast, less than 50% of patients with medulloblastomas or metastatic cancers of the kidney, prostate, or thyroid, and less than 10% of patients with gliomas, harbored detectable ctDNA.”

In addition to offering clues about stage and spread, liquid biopsies can be used to monitor the effects of cancer treatment, give an early warning about possible recurrence, and offer clues to the reasons for treatment resistance.

A second team of researchers used liquid biopsies in colorectal cancer patients to show that early resistance to treatment with epidermal growth-factor receptor (EGFR) inhibitors could be identified by the presence of certain mutations in the blood.

In their research, Sandra Misale, a PhD student from the Department of Oncology at the University of Torino in Italy, and colleagues showed that this resistance can be overcome by concomitant treatment with mitogen-activated protein kinase (MEK) inhibitors.

“We reasoned that tissue biopsies would only offer a snapshot of the overall tumor mass and might therefore be ill suited to capture the multiclonal feature of the resistant disease,” the researchers note, explaining that liquid biopsies are “more likely to capture the overall genetic complexity of tumors in patients with advanced disease.”

In fact, Dr. Diaz’s team found the same mutations in treatment-resistant colorectal cancer patients, suggesting a future clinical application for liquid biopsies. “These data therefore strongly suggest that patients being considered for treatment with EGFR blockading agents should be tested for these additional mutations,” they advise. Patients harboring such mutations “are unlikely to benefit from these agents and would be better served by other therapeutic approaches.”

Tissue Biopsy Can Be Challenging

There is good reason to want to learn about cancer through the blood, said Terence Friedlander, MD, from the Helen Diller Family Comprehensive Cancer Center at the University of California, San Francisco. “For most tumors, a tissue biopsy is quite challenging, in that it’s costly, painful, and potentially risky for the patient,” he explained.

The research by both teams illustrates that there is “a lot of reason to be excited” about liquid biopsies, he told Medscape Medical News. “Together, both of these papers show that you can detect resistance as it’s happening in real time.”

Although the current FDA-approved liquid biopsy measures intact circulating tumor cells (CTC) to give a prognosis of overall survival, the potential predictive value of ctDNA is much more exciting, he said.

“Predictive markers are better because they help guide treatment decisions. In a sense, the ctDNA liquid biopsy allows us to understand specifically what kind of molecular changes are happening in the tumor in real time, which is a very big step beyond where CTCs are today, clinically.”