FDA staff members identified no significant concerns regarding the safety, accuracy, risks, or benefits of the Galleri multicancer early detection (MCED) blood test in a briefing document released ahead of a Medical Devices Advisory Committee meeting scheduled for Wednesday.
The prescription, qualitative in vitro diagnostic test, developed by Grail, is designed to screen adults aged 50 and older for the early detection of multiple cancer types. In the briefing materials, agency staff noted that the majority of U.S. cancer deaths stem from cancers lacking guideline-recommended screening programs.
“Blood-based multicancer detection tests offer the potential to detect multiple types of cancer through a single blood draw,” the staff wrote. “Screening tests, such as Galleri, that detect cancers for which there are no guideline-recommended screening options may provide detection of cancers that would otherwise go undetected, thereby helping to address an unmet medical need.”
The document cautioned that risks associated with false-positive and false-negative results inherent to blood-based screening warrant careful consideration.
While FDA staff typically highlight positive or negative aspects of a device prior to an advisory meeting, they adopted a largely neutral stance on the data from the PATHFINDER 2 study and the randomized NHS-Galleri trial.
PATHFINDER 2 was designed to evaluate the safety of the Galleri test—specifically the diagnostic workup triggered by MCED results—and to assess test performance in individuals eligible for cancer screening. The NHS-Galleri study was a prospective, randomized controlled trial enrolling participants aged 50 to 77 with no clinical suspicion of cancer to evaluate the test’s performance for population screening in the U.K. when added to standard care.
Data presented at the American Society of Clinical Oncology annual meeting in May indicated the NHS-Galleri trial did not meet its primary endpoint of reducing late-stage (Stage III or IV) cancer incidence across a dozen tumor types lacking current screening options, though it did detect more early-stage (Stage I and II) cancers.
The FDA briefing document did not review that primary endpoint. Instead, it focused on test performance and safety data from participants with one year of follow-up in PATHFINDER 2, alongside data from the intervention arm of the first (prevalent) screening round of the NHS-Galleri trial.
Results from PATHFINDER 2 showed Galleri achieved a 12-month episode sensitivity of 35.0%, specificity of 99.85%, positive predictive value (PPV) of 77.0%, negative predictive value (NPV) of 99.07%, and cancer signal origin (CSO) prediction accuracy of 94.3%.
In the NHS-Galleri cohort, the test demonstrated a 12-month episode sensitivity of 31.6%, specificity of 99.74%, PPV of 66.2%, NPV of 98.89%, and CSO predictive accuracy of 91.9%.
On Wednesday, the Molecular and Clinical Genetics Panel will vote on three key questions:
- Whether there is reasonable assurance that Galleri is safe for use in patients meeting the proposed indication criteria.
- Whether there is reasonable assurance that Galleri is effective for that patient population.
- Whether the benefits of the test outweigh the risks for these patients.
The FDA will also seek the panel’s advice on appropriate labeling, including warnings and risk mitigation strategies, and on how best to communicate the test’s performance and limitations to healthcare providers and patients. While the agency is not bound by the committee’s recommendations, it typically follows their guidance.
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