AACR: Love and Confusion with Biomarkers

In a panel discussion at the American Association for Cancer Research's annual meeting, Anna Barker, deputy director of the National Cancer Institute, expressed both feelings of love and confusion with biomarkers. "Biomarkers are kind of in the eye of the beholder," she told attendees. "Biomarkers are promising, but they have limitations right now, in terms of what we [as researchers] believe biomarkers to be, and, for example, what the regulators might think they are." Biomarkers, Barker explained, are not the same as diagnostics — biomarkers intended for clinical use must be qualified and validated under Food and Drug Administration rules, whereas diagnostic tests can be cleared by the FDA's Center for Devices and Radiological Health with data supporting their satisfactory analytical and clinical performance. As such, she said, one validated biomarker could potentially translate into many commercially available tests. "You can have a diagnostic that is not qualified as a biomarker, so it's a little confusing right now," Barker said. "One of the things that we all have to think about is when you're developing a biomarker, is it a biomarker or is it a test? It turns out that those are not the same thing — at least not if you're going to go after regulatory approval." The FDA qualifies biomarkers with data supporting a specific context of use, Barker said, which the agency terms "fitness for purpose." This FDA definition has evolved over the last three years, and it has been "confusing to people," she added. Still, Barker has hope for biomarkers as cancer diagnostics. "We love proteins, and we think they're going to be great biomarkers, but we don't have very many. We love nucleic acids and genes as biomarkers — and some of those are doing some interesting things right now in trials," she said. "So, the potential for biomarkers is vast, that's why we have so much interest — we have so many meetings, we talk about them pretty incessantly."