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Medical Device Daily Senior Staff Writer

One of the most deadly cancers, colon cancer, also happens to be one of the most preventable types of cancer because it can take up to 10 years for pre-cancerous colon polyps to turn malignant. Unfortunately, the invasive nature of colonoscopy, coupled with the fact that not everyone who should be screened for colon cancer has easy access to a gastroenterologist, means that only a fraction of the at-risk population is screened for the disease.

A new stool-based DNA colon cancer screening test, one that can be completed by the patient in the comfort of their own home, has recently demonstrated that it is capable of detecting cancer and pre-cancerous polyps almost as well as colonoscopy. Exact Sciences (Madison, Wisconsin) reported that preliminary analysis shows that its Cologuard colorectal cancer screening test met or exceeded all primary and secondary endpoints of its recently completed Deep-C pivotal clinical trial. The trial was designed to evaluate the test's use for the detection of colorectal cancer and pre-cancerous polyps.

Preliminary, top-line data show that Cologuard demonstrated 92% sensitivity for the detection of colorectal cancer and 42% sensitivity for the detection of pre-cancerous polyps, including 66% sensitivity for polyps equal to or greater than 2 centimeters. The test also achieved a specificity of 87% during the trial.

These detection rates are "statistically very similar to a colonoscopy," Exact Sciences President/CEO Kevin Conroy told Medical Device Daily. "Colonoscopy detects about 95% of cancers," he said, compared to the 92% sensitivity seen with the Cologuard.

Sensitivity measures a test's ability to correctly identify positive results, the percentage of patients who were determined by colonoscopy to have pre-cancerous polyps or cancer who had a positive Cologuard test. Specificity measures a test's ability to correctly identify negative results, the percentage of patients who were determined by colonoscopy not to have pre-cancerous polyps or cancer who had a negative Cologuard test. The trial included 10,000 patients between the ages of 50 and 84 who were at risk for colorectal cancer.

"We are extremely pleased with these results, which we believe strongly support the power and potential clinical use of the Cologuard screening test," Conroy said. "We believe our test could become a great tool in the fight against this terrible disease."

Exact Sciences will submit data from the DeeP-C study to the FDA as part of its pre-market approval (PMA) submission. The Cologuard test was the first device accepted into the FDA-CMS parallel review pilot in December 2011. "It takes two years, potentially, off the time period from FDA approval to Medicare coverage, it saves us the cost of running a separate study for the Medicare population," Conroy said during a webinar hosted by Avalere Health (Washington) last month (Medical Device Daily, March 22, 2013).

The DeeP-C clinical trial achieved all of its endpoints. The co-primary endpoints for the Deep-C study were the sensitivity and specificity of the Cologuard screening test for colorectal adenocarcinoma. The trial included two sets of co-secondary endpoints. The first included sensitivity and specificity of the test for advanced adenomas. The second included non-inferiority of Cologuard to FIT for cancer sensitivity and superiority to FIT for advanced adenoma sensitivity.

"We developed a tremendous test in Cologuard and we wanted to develop that test in the right way, with the right collaboratory, the Mayo Clinic," Conroy said.

Enrollment was conducted at 90 sites to gain a broad demographic sampling of patients, Exact Sciences noted. The study is one of the most extensive colorectal cancer screening studies ever conducted in the U.S. It compared the performance of the Cologuard test to colonoscopy and fecal immunochemical testing (FIT).

"The DeeP-C trial evaluated Cologuard's ability to detect both pre-cancerous polyps and cancer in a large, average-risk patient population," said principal study investigator Thomas Imperiale, MD, professor of medicine, associate director for research for the division of gastroenterology at Indiana University School of Medicine (Indianapolis) and a member of the IU Simon Cancer Center. "There is a significant unmet clinical need for an accurate, convenient, non-invasive colorectal cancer screening test. The data from the DeeP-C trial are very promising. Cologuard may well be a future solution for identifying slow growing polyps much before they develop into cancer."

Each patient result from the Cologuard test was compared to the patient's colonoscopy result and the histopathologic diagnosis of any lesions that were discovered during colonoscopy and biopsied. The study population included 64 cancer patients and 752 patients with pre-cancerous polyps.

Exact Sciences' Cologuard screening test is designed to detect specific changes in a patient's DNA that appear in the stool and often indicate the presence of colorectal cancer or the pre-cancerous polyps most likely to develop into it. The test also identifies the presence of blood in the stool, another indicator of possible colorectal cancer. The latest American Cancer Society colorectal cancer screening guidelines include stool-based DNA testing as a recommended screening option.

"On the pre-cancer detection side the really powerful news coming out of this study is that we saw a 66% detection rate for a 2 centimeter size pre-cancerous polyps and larger, and that detection rate is really outstanding for a non-invasive test," Conroy said.

Ultimately, the Cologuard test has the potential to do for colorectal cancer what the Pap test did for cervical cancer, Conroy said. Because the test is designed to allow the patient to collect the sample at home, the company has built in what Conroy called a compliance engine, giving it the ability to follow up with the patient and answer any questions they have about how the collection works and make sure that they actually return the collection kit.

"We want to be part of the solution," he said. "The best way to cure Colon cancer is to prevent it."

Amanda Pedersen, 912-660-2282;

Published  April 22, 2013

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