Last month, Brigham and Women’s Hospital and Harvard University unveiled VirScan, a diagnostic blood test that reveals more than 1000 different strains of viruses that are currently or which have previously afflicted individual patients. Given that VirScan costs about the same as traditional ELISA assays which only detect a limited number of pathogens one-at-a-time, this is a tremendous leap forward toward personalized medicine. Data gleaned from snapshots of patients’ past viral infections can give doctors clues about patients’ present health, and — perhaps — glimpses into the future.
VirScan is not the only diagnostic of its kind. With the cost of genetic sequencing falling, hopes for a newer, more precise type of blood — and even urine — testing is emerging: the liquid biopsy. Particularly in cancer diagnostics and treatments, the liquid biopsy offers patients painless, minimally- to non-invasive methods of understanding their particular tumors and then tailoring treatments that are targeted to those tumors’ genetic profiles.
Liquid biopsies work because as tumor cells die off — either because of treatment or their natural life cycles — pieces of their mutated DNA sloughs off of the tumor and circulates through the blood stream. In some cases, those pieces of circulating tumor DNA (cDNA) bypass the kidneys and end up in patients’ urine. If liquid biopsies are effective — and the jury’s still out on that — then physicians have the ability to get real time snapshots of how diseases progress in individual patients and a gene-level view of how and whether their patients are responding to treatments.
While liquid biopsies are not yet part of the standard of care, more of them are available to patients than ever before. According to an article in the New York Times “…these tests were rarely used except in research. Now, several are sold, more than a dozen are in development, and some doctors are using them in routine care.” So far, though, there haven’t been any large-scale clinical trials that prove liquid biopsies’ efficacy. Because of that, few insurance companies will pay for the tests. Medicare doesn’t cover liquid biopsies, and in the position statement to its policy regarding molecular profiling for malignant tumors, Anthem describes the procedure as “Investigational and Not Medically Necessary.”
Still, there is hope. One of the challenges in using blood and urine samples in diagnostics has been the ability to sift through mountains of genetic data to pinpoint specific, disease-caused abnormalities. Companies like Guardant Health are homing in on sensitizing technology to decrease error rates so that liquid biopsies become an integral part of keeping pace with disease progression. Guardant’s CEO Helmy Eltoukhy is optimistic that despite hurdles, liquid biopsies, will become a part of routine medical care, allowing physicians and patients real-time “cancer surveillance.”
In an interview with the Wall Street Journal’s Venture Capital Dispatch blog he said, “What we can really do for the first time is active surveillance of cancer. We have anti-virus and anti-malware programs for our computers, but we don’t have this for the body. Ten years from now, we should have [this type of blood test for cancer] at our annual physical examination. That’s how to start the active surveillance of cancer.”