The U.S. FDA approved the PMA application for the Shield test by Guardant Health Inc., a diagnostic for colorectal cancer (CRC) that avoids some of the issues with alternative diagnostic methods. There are lingering questions about Medicare coverage and physician adoption, however, the answers to which may take a year or two to emerge.

Guardant won the support of an FDA advisory hearing for the test in May, although the 6-3 vote in favor was reflective of questions about the ability of the Shield test to pick up cases of advanced adenoma. The committee also wrestled with the prospect that patients would abandon colonoscopy in favor of the Shield test, but lagging compliance with CRC screening recommendations makes it difficult to counter the argument that there is a pressing need for a blood-based diagnostic.

Even the relatively un-invasive nature of fecal tests has failed to inspire a robust level of patient compliance with screening recommendations, a fact which did not prevent an employee of the National Institutes of Health from speaking out against the Shield test at the May FDA advisory hearing. This test is not the first liquid biopsy for CRC to win the FDA’s seal of approval, but the previous example lacked the combination of sensitivity and specificity to carve out a place in the Medicare national coverage determination (NCD).

The labeled indication for the Shield test is as a qualitative method of detection of CRC in average-risk individuals at least 45 years of age. Analysts with Leerink Partners said the labeled indication could have been more problematic as the FDA had the option of requiring that the labeled indication be that of a second-line test. Leerink’s analysts indicated that they expect the CMS to cover the test in the CRC screening NCD for a per-test payment of $895.