Can liquid biopsies become the new trend in cancer diagnostics? The medical world has asked this question for quite some time. The first globally approved liquid biopsy-based test for lung cancer shows that this can work. Yet further findings and research are still required to establish this less invasive method in diagnostics.
We spoke with Jörg Teubner from Qiagen about the new blood test and further developments by the company and looked at the future of liquid biopsies.
Mr. Teubner, how important are liquid biopsies currently in cancer diagnostics?
Jörg Teubner: When we talk about liquid biopsies today, the focus is on what happens in tissue tumors such as lung or colon cancer and the analysis of information relating to DNA or cells obtained from blood samples. Currently, liquid biopsies are primarily used with solid tumors in clinical research. For now, one should add because the subject now also gains momentum in routine diagnostic testing.
In the spring of 2014, Qiagen has obtained the approval for the first liquid biopsy-based lung cancer test. What exactly is this test about?
Teubner: With our test, physicians can determine whether patients with non-small cell lung cancer might respond to a specific drug therapy or not. Free-circulating DNA from blood plasma is analyzed for specific mutations in the so-called EGF receptor in the cell. These mutations can be triggers for this type of lung cancer.
In Germany, we assume that treatment can’t be initiated in up to 20 percent of patients with non-small cell lung cancer because the EGF receptor mutation status could not be determined through a tissue biopsy. For these patients, a blood test is the only way to determine the state of mutations.
To what extent can this method be transferred to other types of cancer?
Teubner: Depending on the type, cancers are usually associated with specific biomarkers and their mutations. Unlike with other types of cancer, this is the EGF receptor in the case of non-small cell lung cancer. This is why this test is not easily transferrable to other types of cancer. However, the basic principle of how the test works – namely by taking a blood sample from a patient, removing the cellular components of the blood and subsequently examining the free-circulating DNA remaining in the plasma for specific biomarker mutations – can also be used for other indications.
In collaboration with other partners, Qiagen develops new methods to extract exosomes from blood and other liquids. Which of these could be used in cancer research and why?
Teubner: By doing this we complete the picture of liquid biopsies. We are currently focusing on three different areas: free-circulating DNA (which is what our already approved EGFR test is based on), circulating tumor cells (here you specifically extract tumor cells) and exosomes.
Exosomes consist of different components such as RNA, DNA and proteins that are dispensed by a cell into its surroundings. We know that these small vesicles can –among other things- be involved in the formation of cancer. The methods we are developing in this area could essentially be used for all types of cancer. This highly interesting field still needs a lot of research, however.
Recently, the German Society of Pathology (German: Deutsche Gesellschaft für Pathologie) commented on liquid biopsies. "Liquid biopsy analyses (…) contain too many uncertainties to make authoritative statements pertaining to diagnostics or treatment," the DGP press release states*. What is a process developer’s take on this?
Teubner: Liquid biopsies can definitely be used in diagnostics. Our approved test that is based on circulating DNA in plasma actually proves this.
However, we also share the opinion of the DGP that biopsies of solid tumors can presently not be completely replaced by liquid biopsies. The question is what you should do in cases where tissue is not available or where frequent exams are necessary to track the course of the disease or adjust the therapy later on. There is a clear trend toward liquid biopsies since multiple tumor biopsies can often not be expected from critically ill patients. Tissue biopsies are invasive and therefore always associated with a certain risk.
I believe that we need to deal more strongly with this topic. First, we definitely need more insights. Nevertheless, there are cases where these methods are already being used in diagnostics today. And this is also how I understand the DGP’s position: to gain a differentiated view on this topic, use the technology when reliable findings are available and continue to research where there is still a need for clarification.