Guardant's liquid biopsy detects 96% of early-stage colorectal cancer cases with a single blood draw: study

Typically, screening for colorectal cancers requires patients to collect stool samples for regular testing or undergo more invasive procedures like colonoscopies, barium enemas and sigmoidoscopies. Those largely undesirable options have resulted in screening rates well below the Centers for Disease Control and Prevention’s goal to see at least 80% of Americans ages 50 and older undergoing regular colorectal cancer screening.

Guardant Health is aiming to improve those stats. Its Lunar-2 liquid biopsy test is designed to catch colorectal cancer in its earliest stages and requires only a standard blood draw, offering a less invasive and time-consuming alternative to the current standards for screening.

On top of making testing more widely accessible, Guardant’s blood test has also been proven in clinical studies to detect signs of cancer with similar accuracy to colonoscopies and other standard screening methods. Data presented at the American College of Gastroenterology’s annual meeting this month showed that Lunar-2 was able to detect stage 1, 2 and 3 colorectal cancer with 96% sensitivity and 94% specificity.

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The newly presented data came from a retrospective study of just under 700 patients diagnosed with early-stage colon or rectal cancer. The study focused on patients with an average risk of developing the disease and included many with asymptomatic cases—comprising 37% of the group—in an effort to demonstrate the test’s widespread use.

When the analysis was limited just to those patients with stage 1 or 2 colorectal cancer, when signs of cancer are particularly difficult to spot in the blood, Lunar-2’s sensitivity dropped only slightly, to 93%. That number slipped to 90% when the test was used to detect cancer in stage 1 and 2 patients who weren’t yet showing symptoms of the disease.

The study was limited by the fact that it was a retrospective analysis of patients already diagnosed with colorectal cancer, Guardant said. The results will be further validated in the ongoing ECLIPSE clinical trial of the Lunar-2 test, which is aiming to enroll 10,000 average-risk patients by the end of this year. If the study is successful, results will be submitted to the FDA as part of Guardant’s application for Lunar-2’s approval.

Still, these early results show promise for the liquid biopsy’s potential as an “easy-to-use and highly accurate” alternative to colonoscopies and stool-based tests, especially as the COVID-19 pandemic has led to a drop in clinical visits for cancer screening, AmirAli Talasaz, co-CEO of Guardant Health, said in a statement.

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Guardant’s work to validate the Lunar-2 test comes amid the rollout of another of its liquid biopsies, this one to detect the recurrence of colorectal cancer, rather than the onset. The Reveal test, which launched in February, sifts through a blood sample to find minuscule fragments of tumor DNA leftover after a patient has undergone surgery to remove the cancer.

The liquid biopsy returns results in about a week and boasts a sensitivity of about 91%. According to the company, the test can spot recurring cancers up to several months earlier than standard imaging procedures and blood tests.

Both the Reveal and Lunar-2 tests will eventually be expanded to detect signs of other tumors beyond colorectal cancer.