FDA Panel Backs Blood Test for Detecting Over 50 Cancer Types

An advisory panel to the U.S. Food and Drug Administration (FDA) has recommended supporting the Galleri blood test, which can detect signals of more than 50 types of cancer from a single blood sample. This recommendation moves the test closer to regulatory approval in the United States, though the FDA's final decision is expected in the coming months and is not bound by the panel's vote. The panel voted seven to two, with one abstention, that the potential benefits of the test outweigh the risks for individuals aged 50 and older. While the vote on safety was unanimous, the efficacy vote was closer, six to four.

Developed by GRAIL, the Galleri test is part of a new generation of early cancer detection methods. It analyzes cell-free DNA in the blood for methylation patterns, chemical changes in DNA that can indicate cancerous activity. If a suspicious signal is detected, the test also estimates the tissue or organ of origin to guide further diagnostic efforts. Professor Ido Wolff, Director of Oncology at Ichilov Hospital, explained that the test aims to find cancer at its earliest, non-metastatic stages, particularly in individuals over 50 where cancer incidence is rising. He emphasized that Galleri is intended to supplement, not replace, existing screening methods like mammograms or colonoscopies.

Data presented to the FDA, including from the U.S. PATHFINDER 2 and U.K. NHS-Galleri studies, showed the test had a specificity of over 99%, meaning very few false positives. In cases where the test detected cancer, subsequent diagnosis confirmed cancer in about 77% of U.S. study participants and two-thirds of U.K. participants. However, the test identified only about one-third of all diagnosed cancers during the follow-up period. The test's ability to predict the cancer's origin was highly accurate, with over 94% accuracy in the U.S. study and 92% in the U.K. study, aiding in directing subsequent imaging and investigation.

While the NHS-Galleri study, involving over 142,000 participants, did not meet its primary endpoint of reducing combined stages 3 and 4 cancer incidence, it did show a reduction in stage 4 diagnoses. Professor Wolff noted that repeated testing over time showed increasing benefit, with long-term projections suggesting a potential 20% reduction in advanced, fatal tumors. However, the studies have not yet definitively proven that the test reduces cancer mortality. The Galleri test is currently available privately in Israel through Oncotest for 4,200 shekels, but it is not included in the national health basket.