- Guardant is one of several companies aiming to develop DNA blood tests that can detect early-stage cancer.
- Test shows for the first time that a blood test really detect colorectal cancer with high sensitivity.
- Subsequent colonoscopy ruled out colon cancer in 10% of people who tested positive with Guardant's DNA blood test.
Guardant Health Inc on Thursday said a pivotal trial of its DNA blood test showed that it detected 83 per cent of colorectal cancers and 13 per cent of advanced adenomas, a cancer precursor, but the results fell short of a rival stool-based test, sending the company's shares sharply lower.
Wall Street analysts, including Puneet Souda at SVB Securities, had predicted the 20,000-person trial would likely show sensitivity of 85-86 per cent for colorectal cancer and 20-25 per cent for advanced adenomas.
Cologuard, a stool-based DNA test, identifies 92 per cent of colorectal cancers and 42 per cent of pre-cancerous polyps, according to data from Exact Sciences, which markets the test.
Guardant's shares, which closed at $41.26, were down 39 per cent at $25 in after hours trading. Shares of Exact Sciences were up 25 per cent at $55.99 after hours.
"We are showing for the first time that a blood test can really detect colorectal cancer with high sensitivity," Amir Ali Talasaz, Guardant's co-chief executive, said in an interview.
Guardant said that a subsequent colonoscopy ruled out colon cancer in 10 per cent of people who tested positive with its DNA blood test.
About 70 per cent of adults aged 50 to 75 are up-to-date with colorectal cancer screening based on all current testing types, according to the US Centers for Disease Control and Prevention.
"This is a huge unmet clinical need," Talasaz said of a blood test for detecting colon cancer. "There are still 50 million people out there who are not complying with colorectal cancer screening."
He said Guardant expects to finish submitting its data to the US Food and Drug Administration early next year, and "hopefully we get FDA approval in the very early part of 2024."
Guidelines from the US Centers for Medicare and Medicaid Services say the agency will reimburse for blood-based biomarker colorectal cancer screening tests with a minimum sensitivity of 74% if they are approved by the FDA.
Guardant is one of several companies, including Exact Sciences and Illumina's Grail unit, aiming to develop DNA blood tests that can detect early-stage cancer.
Guardant is currently enrolling patients in a different trial of its DNA blood test for detecting lung cancer, Talasaz said.