Grail's Galleri Cancer Blood Test Shows Promising Results, Eyes FDA Review

Grail, a biotechnology company focused on early cancer detection, has unveiled detailed data from its Pathfinder 2 study of the Galleri cancer blood test at the European Society for Medical Oncology (ESMO) 2025 conference in Berlin. The results demonstrate significant improvements in cancer detection rates and accuracy, potentially paving the way for a paradigm shift in cancer screening protocols.

Pathfinder 2 Study Results

The Pathfinder 2 study, which included over 23,000 participants aged 50 and older, showed that the Galleri test detected cancer signals in 216 individuals, with 133 subsequently receiving a cancer diagnosis. This translates to a positive predictive value of 61.6%, a substantial increase from the 43% observed in the previous Pathfinder study conducted in 2022.

Key findings from the study include:

• The test demonstrated a specificity of 99.6%, with a false positive rate of just 0.4%.
• More than half (53.5%) of the newly detected cancers were found at early stages (1 or 2).
• 69.3% of cancers were identified at stages 1 through 3, where curative treatment is still possible.
• The overall episode sensitivity for all cancers was 40.4%.

Dr. Josh Ofman, president at Grail, emphasized the test's ability to predict the cancer's location, stating, "Galleri's ability to accurately predict where in the body the cancer signal comes from also helps to guide a more efficient diagnostic workup."

Implications for Cancer Screening

When combined with standard-of-care screenings for breast, cervical, colorectal, and lung cancers, the Galleri test detected approximately three times as many cancers. This finding is particularly significant given that about three-quarters of the cancers detected by Galleri currently lack recommended screening tests.

The improved performance of the Galleri test in this larger study group suggests its potential to become an integral part of comprehensive cancer screening strategies. By identifying cancers at earlier stages and those without existing screening protocols, Galleri could significantly impact cancer mortality rates and treatment outcomes.

Regulatory Path Forward

Armed with these promising results, Grail is preparing to submit a premarket approval (PMA) application to the FDA. The company plans to include data from both the Pathfinder 2 study and an ongoing large-scale trial in the UK's National Health Service (NHS).

The NHS-Galleri trial, involving over 140,000 volunteers, aims to assess the test's ability to reduce late-stage cancer diagnoses. Results from this study are expected in 2026 and will be crucial in supporting Grail's FDA application.

Grail anticipates completing the PMA submission for Galleri, which has already received breakthrough device designation, in the first half of 2026. If the regulatory process proceeds as planned, FDA approval could potentially be granted in 2027.

While the Galleri test is currently commercially available in the United States, FDA approval would likely facilitate insurance coverage and broader adoption, potentially revolutionizing cancer screening practices across the country.