from BioPharmaDive – by Ned Pagliarulo –
As immuno-oncology dazzles and pharma companies race to develop new cancer medicines, a similar boom is underway to speed up and improve the detection of cancers.
“Liquid biopsies” — diagnostic tests to detect cancer biomarkers in the blood — promise a less invasive and more comprehensive way of diagnosing the amorphous disease than traditional methods, such as by tissue biopsy.
A handful of companies are currently marketing liquid biopsies, but commercial applications remain largely limited to improving treatment selection for late-stage cancers. Yet, money is flowing into the space and companies are working to broaden the potential market, pushing development into earlier cancer stages as well as into post-cancer monitoring.
If liquid biopsies can prove effective as a diagnostic tool in the pre- and post-cancer settings, some in the industry predict the market’s value could balloon to anywhere from $20 billion to over $100 billion. Grail, a spinoff of the sequencing giant Illumina, recently announced plans to raise a staggering $1 billion in investor funding to drive development of its pan-cancer screening test.
For that kind of market to emerge, though, liquid biopsy companies will have to figure out how to make the tests more accurate and, more importantly, prove they can actually improve patient outcomes.
Markers in the blood
Traditional biopsies — slicing a tissue sample for a tumor — are a standard tool in oncology to pinpoint a cancer’s mutations and malignancy. After detecting a tumor through a physical exam or imaging, physicians use such biopsies to gather valuable information on the unique attributes of a patient’s cancer.
But tissue biopsies can’t always be obtained and often involved invasive procedures. While some cancers are easily accessed, others are hidden deep inside the body or lurk in critical organs. Beyond the physical challenge, sampling from those tumors can be dangerous to the patients themselves and doesn’t always work.
Luckily, cancer cells share some of the same attributes as normal cells: both shed fragmented strands of DNA and RNA into the bloodstream through apoptosis, or programmed cell death. These strands, known as circulating-tumor DNA (ctDNA) when shed by cancer cells, can be picked up from an intravenous blood draw — giving a potentially transformative way to gather information about a patient’s cancer.
Liquid biopsies use a sample of the blood and then enrichment and next-generation sequencing techniques to identify mutations known to cause cancers from the ctDNA genes.
Liquid biospies can also look for two other types of biomarkers known as circulating tumor cells, or CTCs, and exosomes.
One immediate challenge with liquid biopsies is detection. Circulating tumor DNA is relatively rare compared to the number of hematological molecules found in a blood sample. Circulating tumor cells are even less common.
“The amount of circulating nucleic acid coming out of tumors varies fairly widely, even in patients who often have extensive metastatic disease,” explained Stanley Hamilton, division head of Pathology and Laboratory Medicine at the University of Texas MD Anderson Cancer Center.
The sensitivity of a liquid biopsy to detect ctDNA or CTCs at extremely low concentrations, then, is a crucial factor for proving the test’s utility.