"Pre-cancerous sensitivity, which was the key metric investors were looking at, was well below expectations," Wedbush Securities analyst Zarak Khurshid said, adding that "lower pre-cancer sensitivity may limit the eventual addressable opportunity for the test."
Khurshid was expecting a 55% detection rate for pre-cancerous polyps. Exact Sciences Chief Executive Kevin Conroy, speaking to investors on a conference call, acknowledged that the test's detection rates in the study were not as high as expected, even though they met the trial's main goals.
But he said the data confirm the value of the test in detecting cancer and pre-cancerous conditions. "We don't believe this will be an impediment in any way to the ultimate adoption of this test by physicians and patients," Conroy said.
"I understand that people may be disappointed, but clinically, it just won't make that much difference."
More accurate test
Exact's non-invasive test, called Cologuard, was developed to be a more accurate alternative to currently available non-invasive screenings and an option for people who are not getting a recommended colonoscopy.
The study compared the performance of the test to colonoscopy and faecal immunochemical testing that looks for blood in a stool sample.
The test met the study's primary goals for cancer detection rates. It also met its secondary goals of detecting larger polyps and demonstrating non-inferiority to the FIT screening.
While a colonoscopy is considered the most accurate method of detecting colon cancer and polyps, many people avoid the test, which involves inserting a flexible tube into the colon. Nearly half of those over age 50 have not been screened as recommended.
The trial was conducted on 10 000 patients between the ages of 50 and 84, who were at average risk for colorectal cancer.
Madison, Wisconsin-based Exact Sciences plans to submit the study data to the US Food and Drug Administration as part of its approval application.
Colorectal cancer is the third most-commonly diagnosed cancer in the United States, responsible for about 50 000 deaths a year.