Cancer DNA circulating in the bloodstream of lung cancer patients can provide doctors with vital mutation information that can help optimise treatment when tumour tissue is not available, an international group of researchers has reported at the European Lung Cancer Conference (ELCC) in Geneva, Switzerland.

The results have important implications for the use of cancer therapies that target specific cancer mutations, explains Dr Martin Reck from the Department of Thoracic Oncology at Lung Clinic Grosshansdorf, Germany, who presented the findings at the conference.

Testing for the presence of these mutations in the tumour itself is not always possible, however studies have suggested that DNA from the tumour that circulates in the bloodstream of patients may provide similar information.

The large international ASSESS study aimed to compare the ability of blood testing to detect EGFR mutations with the more standard method of testing the tumour itself.

“We were really asking a question on behalf of patients,” Reck said: “Is there a valid test that can identify an EGFR mutation and give me the opportunity for superior treatment, even if my lung tumour is not accessible for bronchoscopy or CT-guided biopsy? And, are the results of this blood test in agreement with the results of the ‘gold-standard’ tissue test?”

Overall, the study included 1162 matched tissue and blood samples. Comparison of the outcomes of EGFR testing in the two techniques showed an 89% rate of agreement between the blood test and tissue test. Plasma testing identified about half of the patients with EGFR mutations, compared to tissue testing (a sensitivity of 46%).

The tests in this study were not performed in specially selected central labs, but in local labs that are used for daily clinical routine. “This is important, because it does reflect the clinical reality and not a ‘virtual’ trial reality,” Reck said.

“The results mean that for patients who do not have accessible tumour tissue, plasma testing for EGFR mutation turns out to be an attractive option to offer these patients adequate targeted treatment,” Reck added.

Commenting on the study, Dr Rafael Rosell, from the Catalan Institute of Oncology, Barcelona, Spain, expert on the ESMO Faculty on Lung cancer, said: “Cell-free DNA detected in the bloodstream of cancer patients represents an excellent tool to examine genetic alterations that are usually  found through tumour tissue testing. This represents one of the most astonishing phenomena in biology.”

“The results of this study validate that the presence of EGFR mutations in circulating DNA from plasma or serum (fractions obtained from whole blood) can be detected in around half of the patients.”

Already, since this study was performed, improvement of techniques have seen the sensitivity of tests for EGFR mutations in circulating tumour DNA increase further, Rosell noted.

“This work paves the way for further studies and expands the routine use of examining mutations such as EGFR mutations as part of cancer patient care,” Rosell said. European Society for Medical Oncology

Testing for a DNA signature could predict which patients with myeloma – a cancer of immune cells in the blood and bone marrow – are likely to develop more serious disease, with a reduced chance of survival.

A team at The Institute of Cancer Research, London, found that cancer cells with the signature gain more DNA mutations than those without.

These mutations make the cancer more genetically complex, and more likely to evolve into treatment-resistant forms.

The study used genetic sequencing to analyse all of the genes of 463 patients with myeloma.

It searched for a genetic signature caused by a molecule called APOBEC, which edits DNA code in healthy immune cells to create the genetic diversity that allows them to adapt to threats from infection.

The molecule edits in a particular way, leaving a distinctive pattern that can be picked up by researchers through genetic sequencing.

The new study shows that APOBEC molecules become overactive in myeloma, or act on genes that they are not supposed to – leading to more advanced cancer. Eighteen of the patients analysed in the study had the APOBEC signature in their cells.

Along with the APOBEC signature, the researchers discovered that a number of other DNA and chromosome mutations were associated with more severe forms of the disease – including the common cancer gene, MYC.

Study leader Professor Gareth Morgan, who conducted the research as Professor of Haematology at the ICR, said:

“The treatment of myeloma has improved in recent years – but there are still a significant number of patients who succumb to the disease. Our research has identified, for the first time, several genetic features that indicate which patients are at high risk of developing more advanced cancer.

“In the future we hope to be able to use this information to test for patients most at risk, and be able to target specific treatment to their individual needs, bolstering their chance of survival.”

Eric Lowe, Chief Executive of Myeloma UK, said: “Adapting the current one-size-fits-all approach to treatment is critically important to ensure myeloma patients only receive treatment that is stratified to the specific nature of their disease and which has a high probability of working. We are grateful to the myeloma research team at the ICR for their hard work and dedication and are very proud that our programme grant is being used to fund such high-quality research, producing data that patients will benefit from in the clinic.’’
ICR Institute of Cancer Research

This month in Breast Cancer Research and Treatment, Khalil and his colleagues at Case Western Reserve University proved the power of persistence; from a pool of more than 30,000 possibilities, they found 38 genes and molecules that most likely trigger HER2+ cancer cells to spread.

By narrowing what was once an overwhelming range of potential culprits to a relatively manageable number, Khalil and his team dramatically increased the chances of identifying successful treatment approaches to this particularly pernicious form of breast cancer. The HER2+ subtype accounts for approximately 20 to 30 percent of early-stage breast cancer diagnoses, which are estimated to be more than 200,000 new breast cancer diagnoses each year in this country, leading to approximately 40,000 deaths annually. Several cancer chemotherapy drugs do work well at early stages of the disease — destroying 95 to 98 percent of the cancer cells in HER2+ tumors.

“Eventually though, many of these patients develop resistance to the drugs, and the 2 to 5 percent of the remaining breast cancer cells begin to grow and cause tumours again,” said Khalil, assistant professor in the Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine. “We want to develop a strategy to target the genes responsible for enhancing HER2 oncogenic activity and increase the chances of eliminating the tumour entirely at the early stages of the disease.”

In this study, Khalil, also a member of the Case Comprehensive Cancer Center, and colleagues chose an innovative approach that went beyond merely comparing gene expression in normal and in HER2+ cancer-affected breast tissue. Other scientists tried such a straightforward comparison but found themselves swamped by hundreds and even thousands of gene expression differences. Instead, Khalil designed a study where the offending genes would stand out. He and colleagues compared gene expression differences among HER2+ breast cancer tissues of uncontrolled HER2 activity with those having greatly diminished HER2 activity. Ultimately their work revealed 35 genes and three long intervening noncoding RNA (lincRNAs) molecules were most associated with the active HER2+ cells.

To obtain special breast cancer tissues in HER2-active and HER2-diminished states, Khalil collaborated with oncologist Lyndsay Harris, MD, who had served as correlative science principal investigator for a clinical trial of the drug trastuzumab, which involved Brown University, Yale University and Cedars-Sinai. Harris, now professor of medicine, CWRU School of Medicine, and director of the Breast Cancer Program, University Hospitals Seidman Cancer Center, obtained the preserved HER2+ breast cancer tissues for Khalil’s study from two intervals — before and then during the trastuzumab clinical trial. The drug works by disrupting HER2 activity, which in turn prevents this recalcitrant protein from launching uncontrolled cell growth.

From this collection of HER2+ breast cancer tissue, Khalil and colleagues got to work on determining which genes and other genetic components stood out. First, they applied RNA sequencing and then compared the sequences in tissues collected before trastuzumab curtailed HER2 activity with those collected later when HER2 activity declined sharply. Next, investigators grew the HER2+ breast cancer tissue cells in the laboratory and examined genes prominent in the cell culture (in vitro) model of the disease. Forty-four genes stood out during this portion of the investigation. Finally, Khalil and colleagues obtained publically available RNA-sequence data sets comparing HER2+ breast cancer with matched normal tissue and found that 35 of those 44 genes passed through this third filter.

“In our investigation, we essentially went from thousands of genes and narrowed it down to 35 genes,” Khalil said. “A lot of those genes made sense in terms of carcinogenesis. When they become upregulated because of increased HER2 activity, many of these genes are involved in increased transcription and increased cell proliferation, which are hallmarks of cancer cells.”

The investigators applied the same comparative analysis — RNA sequencing, growing cells in culture and inhibiting HER2 protein — to observe the role of lincRNAs. Khalil and colleagues only discovered this special group of RNA genes in humans in 2009, and scientists now are slowly unraveling the mystery of lincRNAs. For this study, investigators uncovered three standout lincRNAs that are modulated in activity when subjected to increased HER2 activity.

“For the first time, we have shown that these lincRNAs can also contribute to this HER2+ breast cancers,” Khalil said. “So we added another layer of complexity to the disease with lincRNAs. However, these lincRNAs could potentially open the door for RNA-based therapeutics in HER2+ breast cancer, a therapeutic strategy that has great potential but has not been fully tested in the clinic yet.” Case Comprehensive Cancer Center

With more than 200 million global users of statins, these medications are the very definition of ‘blockbuster.’ By stopping a substance the body uses to make cholesterol, statins can help stave off heart attacks and strokes — the top two causes of death worldwide. But in a significant percent of patients — up to 30 percent by some reports — statins can also eat away muscle tissue, causing weakness, muscle pain and in rare cases, potentially deadly kidney and liver damage.

And the problem could grow larger. Under the most recent heart disease prevention guidelines issued by the American Heart Association and American College of Cardiology, the potential number of candidates for statin therapy in the US jumped from 43 million to 56 million.

‘As doctors follow the current guidelines, we expect that nearly half of Americans ages 40 to 75 and most men over 60 may be prescribed a statin,’ said Joseph Kitzmiller, MD, PhD an associate director of the Center for Pharmacogenomics at The Ohio State University Wexner Medical Center. ‘We currently have a limited ability to predict clinical outcomes and potential side effects for any of those individual patients — many of whom will be on a statin for the rest of their lives. In general and for most patients, statins are largely beneficial. Unfortunately, not all patients benefit and some are harmed by statins.’

Kitzmiller, who has devoted his career to untangling the many ways that genetics influence how patients respond to their medications, thinks that statin dosage recommendations need also to consider common genetic variants the affect drug exposure.

‘The muscle toxicity associated with statins is largely about exposure, and exposure is significantly affected by a patient’s genetics,’ Kitzmiller explained. ‘If you give two people 20 milligrams of a statin, and one of them has a polymorphism, or gene variation that changes the way the body processes that statin, it may be as though you’ve given them two or three times as much medication.’

Kitzmiller is team, which is primarily studying simvastatin, have already identified a gene variation that decreases statin metabolism — making people more susceptible to adverse events.

‘For our patients carrying this genetic variant, simvastatin doesn’t break down as much in the liver. This means more of the drug is in their bloodstream, increasing their exposure and potential for muscle toxicity,’ said Kitzmiller. ‘For these people, a lower dose of simvastatin could potentially deliver the same benefits while causing fewer side effects.’

Kitzmiller also found that a patient’s likelihood for carrying a genetic polymorphism depends on their race. Recent work by his research team suggests that the effect size also varies significantly across racial groups. One genetic variant resulted in a nearly 3-fold increase in simvastatin concentrations for African-Americans but only a modest increase for Caucasians.

‘That can have incredible clinical significance, especially since African-Americans often suffer higher rates of drug adverse outcomes and higher disease mortality rates despite receiving similar or even identical treatment,’ said Kitzmiller, who is also an associate professor in the Department of Pharmacology at Ohio State’s College of Medicine.

His team has also recently developed a blood test that can simultaneously measure the quantities of three different types of statins and their metabolites, which indicates how much of a medication the body has metabolized. This type of tool is essential to help scientists establish connections between genetic profiles and the variation in how statins are absorbed, transported, distributed and excreted. Kitzmiller is in the process of developing a multigene test that could tell clinicians if their patients have any of the genetic culprits that are likely to lead to muscle problems or other side effects from statins. He hopes to bring this test to clinical trials later this year. Science Daily