- Guardant Health said that its blood test to screen for cancer caught 83% of colorectal cancer cases.
- Guardant says this could unlock an $20 billion market for colorectal cancer screenings.
A new era in cancer screening could be starting soon.
Instead of having to undergo uncomfortable procedures like colonoscopies, it might be possible to detect cancer from a simple blood draw — also known as a liquid biopsy. On Thursday, Silicon Valley-based biotech Guardant Health announced that its blood-based cancer screening test correctly caught colorectal cancer cases in 83% of people who had the disease. It also correctly predicted that people did not have colorectal cancer 90% of the time.
In a press release, the company said that it would use these study findings to submit the test for FDA approval in the first quarter of 2023.
"We've been working steadily for many years to reach this milestone," Guardant Health co-CEO AmirAli Talasaz said in an investor call on Thursday evening. "As of today, blood-based CRC screening is a reality."
Guardant's stock tumbled after the results were announced
Not everyone was excited about the trial's results, and Guardant's stock tumbled 27% on Friday morning. SVB Securities analyst Puneet Souda said that while the results are likely good enough for the test to gain approval, it won't be a first choice for colorectal cancer screening.
That's in part because the test was only able to correctly detect advanced adenomas, or noncancerous tumors that indicate a risk for colorectal cancer, 13% of the time. A competing product called Cologuard is more effective at detecting similar types of precancerous lesions, using a stool sample. The stock of Exact Sciences, which makes Cologuard, climbed 26%.
Colorectal cancer is one of the most common cancers in the US, according to the American Cancer Society, with almost 45,000 new cases diagnosed each year. It's also deadly — it's the third leading cause of cancer-related deaths in both men and women, and is expected to cause more than 52,000 deaths in 2022. In 2020, it was the cause of death of Black Panther star Chadwick Boseman.
But colorectal cancer is also preventable, and the death rate has been steadily dropping thanks to increased screenings in the past several decades. Currently the US Preventive Services Task Force recommends that adults in the US start getting screened for colorectal cancer at age 45 using a variety of screening tests, such as stool tests, sigmoidoscopies and colonoscopies. People who aren't at high risk for colon cancer need a colonoscopy once every 10 years.
The study results could still unlock a multi-billion dollar market
Guardant's late-stage clinical trial, called ECLIPSE, is the most robust study to date showing the effectiveness of a blood-based screening test for cancer. The test works by detecting tiny particles called circulating tumor DNA, or ctDNA, that are shed by cancerous tumors into the bloodstream.The ECLIPSE trial tested the company's blood test, called Shield, on more than 20,000 patients.
In the Thursday investor call, Guardant estimated that the total market for the colorectal cancer screening alone could be $20 billion.
The company already has several products on the market, including Guardant360CDx, an FDA-approved blood test to test cancer genomic markers that could help show what treatments the cancers are susceptible to. Additionally, Shield is already available in a limited number of doctors offices.
The company also expects that the test will be included in national colorectal cancer screening guidelines by 2026.
According to the research firm Sentieo, Talasaz has said at multiple conferences that the cash price of the test will be $895.
It remains to be seen who will be on the hook for paying for these tests. Guardant does not yet know whether the blood test will be covered by Medicare, Medicaid, or private insurance companies, though the test is accurate enough that coverage seems likely according to guidelines for the Centers for Medicare and Medicaid Services.
Five years from today, Talasaz told Insider in October, "We could have a blood-based screening test for colon cancer using blood for over 130 million people in the United States with no out of pocket cost."
Are colonoscopies a thing of the past?
Unfortunately, a blood-based test won't be completely replacing colonoscopies any time soon.
Colonoscopies are still the gold standard of colorectal cancer screening, despite involving sedation and hours of unpleasant physical preparation. That's because, Souda told Insider in a May interview, colonoscopies are an interventional procedure as well as a diagnostic procedure. In other words, not only are they a screening tool, but they can also be used to snip off precancerous polyps if they are found.
But liquid biopsies are a more comfortable test. Talasaz said that in doctors offices that are already using the blood test, more than 90% of patients are willing to take the test — compared to about 70% of eligible patients that get current forms of screening. And more patients screened means more chances for early cancer to be detected, and lives to be saved.
Guardant is the first in a series of companies working on similar tests
Guardant is the first company to cross the finish line with a late-stage clinical trial to validate its liquid biopsy test. Other biotech companies including Freenome, GRAIL, and Exact Sciences are also developing their own liquid biopsy tests to detect early-stage colorectal cancer.And while colorectal cancer is the first cancer that is being studied for a blood-based screening, it certainly won't be the last. In January, Guardant enrolled its first patient into a clinical trial to determine whether it could use its blood test to detect lung cancer in high-risk adults.
Not all cancers will be able to be detected via blood though, because not all tumors shed DNA into the bloodstream. "There are certain cancers that are just not going to be amenable to liquid biopsy," Souda said.
This article was updated on December 16, 2022 with analyst comments and stock reactions for Guardant and Exact Sciences.