We’ve all heard that dust is at least partly made up of dead skin cells. However true or untrue that may be, living tissue that is growing rapidly, such as a cancerous solid tumor, does indeed shed dead cells.
When a person has a tumor that is growing, it sheds dead cells and their contents—including a unique DNA signature—into the bloodstream. A Redwood City, CA-based company called Guardant Health has developed a technology that is able to pinpoint the tiny fractions of tumor DNA in a blood sample from a person with a cancer, subsequently allowing Guardant to analyze the tumor for mutations and help physicians prescribe therapies, according to CEO Helmy Eltoukhy. Different mutations occur in a tumor over time, even in tumors of the same type, and potentially require different treatments.
Called Guardant360, the technology is intended to replace invasive and expensive surgical biopsies, in which doctors remove a piece of the tumor to sequence and monitor its how the tumor changes over time. Guardant announced this morning it has received almost $100 million in a Series D financing round led by OrbiMed Advisors to attempt to bolster the use of its diagnostic tool nationally and to potentially develop other uses for the test, such as to identify cancer in earlier stages, Eltoukhy says.
“The only way of keeping ahead of those diseases and tracking those mutations has been through surgery, through doing a tissue biopsy and physically cutting a piece of the tumor out and sequencing it,” he says. “What we’re able to do is essentially get the same, or sometimes better performance to tissue biopsy, but through two teaspoons of blood.”
With the tumor DNA found in the blood, the company can accurately construct the genome of the tumor, helping physicians choose what drugs may best treat the cancer. Guardant can also monitor the tumor for mutations to help prescribe new treatments.
A typical biopsy can cost around $14,000, plus a few thousand more for sequencing costs, while Guardant charges “a little over $5,000” for its service, Eltoukhy says. Biopsies also are typically invasive procedures, with higher associated risks than drawing blood samples, and require potentially painful recovery time, he says.
Founded in 2012 by Eltoukhy and a colleague at San Diego, CA-based Illumina, AmirAli Talasaz, Guardant has now raised about $200 million in total venture funding. Previous investors Khosla Ventures, Sequoia Capital, Lightspeed Venture Partners, Pejman Mar, Formation 8, and Heritage Group also participated in the Series D round.
Guardant is using the new funding to gain greater adoption among the 10,000 or so oncologists in the U.S. Though the company has had 2,000 of those oncologists order tests for 20,000 patients so far, many of those phsyicans are those already familiar with genetic testing, Eltoukhy says.
“There are a lot who don’t use it with everyday care patients,” he says. “A good portion of the money will go toward expanding our education component in the market, really showing what the utility is.”
Other companies developing similar diagnostic technology, known generally as a liquid biopsy, as Xconomy reported in a detailed profile of Guardant in 2014. Those companies include Epic Sciences of San Diego, CA and Houston,TX-based ApoCell.
Eltoukhy contends that Guardant has the industry’s most comprehensive liquid biopsy. While some of its competitors only test certain genetic hot spots, Guardant says it studies 70 genes for four potential alterations.
Guardant has also expanded its work with pharmaceutical companies, in an attempt to help identify cancer patients who might be candidates for clinical trials, Eltoukhy says. Only about 3 percent of eligible patients actually get enrolled in clinical trials, and the ease of Guardant’s blood test makes it more appealing than requiring potential patients to have biopsies, especially if they aren’t selected, he says.
“We can accelerate these trials dramatically, and we can accelerate our view of what’s happening with the drug and during the trial,” Eltoukhy says.
Guardant also hopes to build a version of the test that would allow for pre-symptomatic detection of cancer, or even to detect whether a patient who has already been treated may get a cancer back, Eltoukhy says.
“If you can cut it out early while it’s still curable, that will, until we have more powerful therapies, be the most efficient way of eradicating the disease,” he says.