Guardant Health Inc (GH.O) on Thursday said a pivotal trial of its DNA blood test showed that it detected 83% of colorectal cancers and 13% 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% for colorectal cancer and 20%-25% for advanced adenomas.
Cologuard, a stool-based DNA test, identifies 92% of colorectal cancers and 42% of pre-cancerous polyps, according to data from Exact Sciences (EXAS.O), which markets the test.
Guardant’s shares, which closed at $41.26, were down 39% at $25 in after hours trading. Shares of Exact Sciences were up 25% at $55.99 after hours.
“We are showing for the first time that a blood test can really detect colorectal cancer with high sensitivity,” AmirAli Talasaz, Guardant’s co-chief executive, said in an interview.
Guardant said that a subsequent colonoscopy ruled out colon cancer in 10% of people who tested positive with its DNA blood test.
About 70% of adults aged 50 to 75 are up-to-date with colorectal cancer screening based on all current testing types, according to the U.S. 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 U.S. Food and Drug Administration early next year, and “hopefully we get FDA approval in the very early part of 2024.”
Guidelines from the U.S. 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 currently enrolling patients in a different trial of its DNA blood test for detecting lung cancer, Talasaz said.