A key advisory committee that reviews medical devices for the Food and Drug Administration will meet today to vote on whether the agency should approve the first multi-cancer blood test. Grail, the company that makes the Galleri blood test under review, says it can detect up to 50 forms of cancer, many of which are not routinely screened for today.
The panel of independent experts will hear from Grail, FDA officials and the public before voting on a recommendation. The FDA often follows the advice from its panels, but does not have to. Ultimate approval by the agency could mean insurance reimbursement for the test, which costs $949.
There are hundreds of companies chasing the promise of blood tests to detect cancer, which is done with a simple blood draw and could help detect disease earlier by looking for genetic material or other cancer markers shed in blood or saliva. Grail says its Galleri test should be additive to standardized cancer screenings, like colonoscopies and mammograms, and not be used as a replacement.
While blood tests for cancer already exist in the market, none that screen for multiple cancers has undergone safety and accuracy reviews to win FDA approval so far. Many doctors and patients hope such technology will ultimately help detect disease earlier, when more treatment options could be possible.
The financial incentives to win FDA approval also became far more powerful after Congress approved Medicare to cover multi-cancer detection tests that are greenlighted by the agency. Based on its promise, the FDA expedited its review of Galleri, which is the furthest along in that approval process.
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As such, Galleri is seen as a kind of bellwether for the whole industry — and for the potential use of a blood test to screen for cancers in general.
“It’s a new era for early cancer detection, and if the FDA approves it, it validates the overall concept,” says Cristian Tomasetti, director of City of Hope cancer center’s early detection and monitoring division. In 2018, Tomasetti was part of a team that developed a competing blood test technology that is the basis of a test made by Exact Sciences (since purchased by Abbott), which is also pursuing FDA approval. (Tomasetti is no longer involved with that company.)
The questions to answer
The FDA laid out key questions for the committee to answer about Galleri, centered on whether the clinical data show the test detects cancers reliably and early enough to justify use of such terms in its marketing. The agency also wants to consider harm from false results, and potentially require the company to include caveats in its marketing, such as warnings that a false negative does not rule out the presence of cancer, nor a positive detection signifying cancer.
The advisory committee will review two major clinical studies conducted by Grail, including one involving more than 140,000 patients in the U.K.’s National Health System, and another of over 35,000 North American patients, all over the age of 50. The interpretation of those studies has been somewhat controversial. On the one hand, the Galleri tests did not meet their primary end point of reducing mortality overall, nor did it reduce the combined number of Stage III and IV cancers. But in subsequent updates to its NHS study, Grail clarified that Stage IV cancer diagnoses (not combined with Stage III) decreased over its three-year study period, suggesting tests may have shifted cancer diagnosis to earlier stages.
While the trials have not fully proven the test’s benefit, the key underlying question to the inquiry — not just for the FDA, but also for patients and doctors — is whether the Galleri test is accurate enough and can reliably catch cancers early enough to reduce deaths from cancer.
Tomasetti acknowledges that Galleri’s tests did not meet their end points in their clinical studies. But he says that’s in large part because the study specified very ambitious goals, such as showing reductions in mortality within a short period of three years. Mortality reductions are typically measured over the long term. Tomasetti says there are other problems that arise from the short duration of the studies; namely, in the initial years of testing, one would expect to detect more late-stage cancers that already existed in the population.
“This is kind of a technicality,” that the study didn’t meet its initial endpoint, Tomasetti says. “To me, it doesn’t mean that the study — in terms of substance — failed to show evidence of what [multi-cancer detection tests] can actually do.” He says longer-term studies are needed to confirm that using the tests regularly will help shift diagnoses from Stage IV to earlier stage diagnoses. Based on the totality of data, Tomasetti says he thinks the FDA appears poised to approve Galleri’s test.
Oncologist Tom Beer agrees. Beer is chief medical officer for Abbott Cancer Diagnostics, working on a multi-cancer test called CancerGuard, which is also seeking FDA approval. Beer also sees patients in his clinical practice in Oregon, and says 70% of cancer diagnoses and deaths are from diseases like pancreatic cancer, for which no screening exists.
“I’m keenly aware every week when I’m in the clinic, of how many patients are diagnosed with cancers that we don’t screen for,” he says.
