Cancer blood test moves one step closer to FDA approval

The future of cancer screening could fit inside a single vial of blood.

An independent FDA advisory panel voted yesterday to recommend Galleri, a cancer-screening blood test designed for adults 50+ from biotech company Grail. The FDA isn’t required to follow its advisers’ recommendation, but often does.

How it works: Galleri can screen for up to 50 types of cancer from a single blood draw, most of which aren’t routinely screened for today. It’s designed to detect cancer-specific methylation patterns in DNA fragments, which are often present before symptoms of cancer later appear.

Plenty of promise, but also some question marks

The advisory committee reviewed two major clinical studies conducted by Grail, the interpretation of which has been somewhat controversial.

• On one hand, the clinical studies did not show a reduction in overall mortality while using Galleri tests, nor a reduction in the combined number of Stage III and IV cancers.
• But later updates to one of Grail’s studies showed it reduced Stage IV cancer diagnoses not combined with Stage III, suggesting the test may have shifted cancer diagnosis to earlier stages.

Grail says its Galleri test should be used alongside standard cancer screenings like colonoscopies and mammograms, and not as a replacement.

Zoom out: No multi-cancer screening blood test has ever received FDA approval, making Galleri a potential bellwether for hundreds of companies pursuing similar technology. Approval could also open the door to Medicare and private insurance coverage.