Liquid Biopsy and Colorectal Cancer

A liquid biopsy option for potential colorectal cancer patients.

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide, accounting for more than 600,000 deaths each year. When diagnosed early, before cancer has spread, the relative five-year survival rate for CRC is 90%, but only approximately four out of 10 CRC cases are detected early. Among individuals undergoing surgical treatment for CRC, recurrence occurs in 30-50% of all cases, the majority of which present in the first 2-3 years following the initial diagnosis and treatment. Unfortunately for these patients, current recurrence monitoring tests frequently fail to detect disease at a point when clinical intervention has the best chance to be effective.

Clinical Genomics, a private company developing diagnostic tools for colorectal cancer, recently launched a blood-based test for CRC recurrence monitoring. Colvera is a qualitative test that indicates the presence or absence of two genes—BCAT1 and IKZF1—that become epigenetically silenced in CRC. The test measures hypermethylation—a change associated with cancer development in these two genes—as a means to detect circulating tumor DNA (ctDNA), the fragments of genetic material that leak from a tumor into the bloodstream.

Unlike DNA mutations, which may be frequent in cancer but can also vary widely between patients and may undergo mutation shifts as disease progresses, methylation is a stable feature in tumors that is readily measured. Colvera is not intended to stratify the risk of recurrence in colorectal cancer patients, but rather to identify the presence of disease at the time of testing by detecting the presence of BCAT1 and IKZF1 gene methylation. Methylation of these genes is an early molecular change in the neoplastic pathway, and its detection may enable earlier diagnosis of recurrence and initiation of appropriate follow-up testing and treatment.

Peer-reviewed data recently published in Cancer Medicine compared the sensitivity and specificity of the test with those of CEA in patients undergoing surveillance for recurrent CRC following induction of remission. The data demonstrated that Colvera detected twice the number of recurrence cases as carcinoembryonic antigen (CEA) testing, the standard blood test used for CRC recurrence monitoring.

The new method only requires a peripheral blood sample, and the test can be administered along with other CRC surveillance tests, including CEA. It does not require specialized equipment or modifications to clinical protocol, allowing physicians to incorporate the test as part of their routine CRC recurrence monitoring program. As a blood-based test that has been shown to detect significantly more CRC recurrence cases than CEA, it has the potential to fill an urgent unmet clinical need and may help to improve patient outcomes.

Colvera will be performed in a Clinical Genomics’ dedicated CLIA-registered laboratory in Bridgewater, N.J. Quest Diagnostics, provider of diagnostic information services, will provide specimen collection and logistics services for the test orders, and it is being rolled out nationally in 2017.

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