What Is a Liquid Biopsy?
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I have been reading a lot about liquid biopsies quite possibly changing the way we analyze tumors!
According to the NCBI (National Center for Biotechnology Information), “Certain fragments of DNA shed by tumors into the bloodstream can potentially be used to non-invasively screen for early-stage cancers, monitor responses to treatment and help explain why some cancers are resistant to therapies.”
Did you know that a liquid biopsy offers a real-time view to track and monitor response to therapy and tumor burden in a timely manner so physicians can rapidly respond and adapt to changes in a tumor during the course of therapy?
I reached out to Dr. Veena Singh who is the Senior VP and Sr. Medical Director of Biocept to learn more about this cutting-edge technology.
I asked Dr. Singh, to explain what a liquid biopsy is in layperson speak. “A liquid biopsy for cancer patients is a blood test that analyzes tumor products shed into the blood by all regions of a tumor, including the original (primary tumor) and metastatic sites. The analysis is done through circulating tumor cells (CTCs) and/or fragments of DNA from the tumor cells (cfDNA).”
Dr. Singh went on to explain that today, liquid biopsy tests are used to identify genetic mutations and to determine if patients are a match for targeted therapy options and to monitor tumors for a reception to treatments. This is done by comparing the tumor DNA with the DNA from normal cells (white blood cells) to detect and monitor genetic alterations.
At this early stage in the test, I was curious as to what types of cancer this test would be most reliable for. Dr. Singh, responded, “Biocept currently offers commercial tests targeting lung, breast, gastric, colorectal and prostate cancers as well as melanoma. To date, most of our clinical and validation data have been generated in patients with lung and breast cancer. In lung cancer, it is often hard to obtain tissue for detailed genetic analysis, and with the rapidly evolving mutational landscape, multiple biopsies are not practical. The liquid biopsy offers a minimally invasive method of monitoring as well identifying genetic and protein biomarkers in a contemporaneous manner to tailor therapy options. In breast cancer, predictive biomarkers can change throughout the course of the disease and a liquid biopsy offers an alternate way to track these changes.”
Information is powerful. So, I asked if the liquid biopsy was able to give the oncologist more information about a tumor. Dr. Singh responded, “Tissue-based testing to establish a diagnosis of cancer is still the gold standard. However, due to issues of intertumoral heterogeneity and sampling actionable biomarker information could potentially be missed in a patient. Since tumor material is shed from all areas of the tumor (primary and metastatic) into the blood, a liquid biopsy offers an added benefit when tissue is sub-optimal (few tumor cells) or biomarker analysis is negative (possible false negative). Another area where liquid biopsies can have an important role is monitoring how tumors are responding to treatment.”
My immediate thought was that this test should be recommended as a yearly screening protocol for cancer survivors. I learned that additional large population-based studies would be required before that kind of protocol would be recommended.
So many women email me to share their stories. As we know, even with all the science that comes into play with modern medicine, applications and interpretations are frequently not black and white. Often women are faced with the daunting task of deciding, along with their specialists, what course of treatment they should sign up for. This is not an easy task. As you can imagine, once you hear the “C” word, it is a seriously important decision.
I asked Dr. Singh if this blood test could help an oncologist determine which treatment plan is going to be productive for their patients, thereby helping women avoid unnecessary chemo or surgeries? She did confirm that this test could potentially change clinical decisions. Dr. Singh is confident that the Biocept tests can identify actionable biomarkers that are commonly receptive to targeted therapy options. I have been known to get pretty excited about a new pair of shoes, but frankly, in my head I heard a full on chorus singing, “Amen” when I heard this!
Many women have been diagnosed with DCIS (Ductal Carcinoma in Situ). I get email after email from women having so many biopsies on their breasts that they can hardly recognize their breasts anymore. It is very difficult for women to know what course of action is going to give them the best screening. I asked if this test could be an option for women diagnosed with DCIS to replace all of the biopsies that often disfigure a women’s breast? Sadly, this test has only been validated for patients with an established diagnosis of invasive cancer. I am not a doctor or scientist, but if I had a diagnosis of DCIS, I would ask for the test!
I was curious if there was a specific scenario where this less invasive biopsy had given a patient a faster, more accurate diagnosis? Dr. Singh was excited to report, “We have had anecdotal patient cases where we have identified a genetic alteration that resulted in a change of therapy with patients responding in a matter of weeks to the therapy change. For example, patients with HER2 amplification responding to anti-HER2 treatment or patients with lung cancer wherein we identified an actionable mutation responding to treatment. Due to the ability to monitor the tumor through a liquid biopsy, we have seen the mutation or gene alteration disappear after treatment.”
Many of us our Grandmas and are thrilled that there is now DNA testing for birth defects. Although my pregnant daughter was a few months shy of 35, I made sure that she had those tests. I was curious how this technology was similar or different than that DNA test? Apparently it is similar in concept but different in application. The liquid biopsy is focused on oncology and actionable biomarkers.
I wanted to understand how confident Biocept was that the tests results could be relied upon.
Dr. Singh replied “We have a number of publications on our website that compares our results to standard tissue results. Most recently, during a presentation at the UCSD Moore’s Cancer Center Translational Oncology Symposium Biocept’s liquid biopsy test demonstrated greater than 93% concordance in detecting EGFR mutation with tissue biopsy in 74 patients diagnosed with lung cancer. In addition, we run routine daily quality controls for all steps of our process.”
I was curious as to how Biocept’s test was different than other companies. There are other companies who do liquid biopsies, so, I had to ask if all liquid biopsies are created equal? Dr. Singh was pretty clear on this, “No, because performance characteristics (sensitivity, specificity) vary. Our assays are the first and only in the industry that interrogates both CTCs and cfDNA in a highly sensitive manner. The advantage of this is that we use material that yields the most information e.g. protein status on CTCs, which requires an intact cell and using DNA fragments for gene mutations”.
My layperson’s brain was working overtime. I kept thinking that someday this test should be given as part of one’s yearly health screening. But we all know that we would need large, controlled studies for this to happen. Patience is a virtue, but I must admit, not one I possess. There are so many women out there who will be able to benefit from this great science.
My Motto: Suffering in silence is OUT! Reaching out is IN!