Geoffrey R. Oxnard, MD
Preliminary research has shown the potential application of cell-free DNA (cfDNA) in detecting cancer and directing treatment decisions, explained Geoffrey R. Oxnard, MD; however, the approach requires clinical validation before it can be used in practice.
, Oxnard, an associate professor of medicine at Harvard Medical School and a thoracic oncologist at Dana-Farber Cancer Institute, discussed the use of cfDNA as a potential method of cancer detection and subsequent assessment of treatment response in patients with solid and hematologic malignancies.
OncLive: What are some ways in which cfDNA is being used to detect cancer?
: CancerSEQ is an assay that uses a next-generation sequencing (NGS) panel to look for key mutations in addition to proteomics. GRAIL is developing a broad genome-wide assay that looks across the entire genome for any abnormal signals; this is done by deleting the white cell signals and leaving the hidden signal that may be related to cancer. [However], there's a long road ahead of us before we will be able to develop a test that can help healthy patients know whether they have cancer or not.
Additionally, who are the right patients for this and what is the performance of an assay in that regard? What sensitivity should we expect? How accurately can I tell a patient they’re going to recur or not? Just like in advanced cancer, sensitivity is going to be average. We're not going to have 100% certainty that a patient is going to recur or not, but we do want to make sure that a test that says, “Cancer is present after surgery,” is reliable. Those are the kinds of assays I hope we can offer our patients sometime soon.
What work still needs to be done in order to get to that point?
Reports so far are largely preliminary validation rather than a rigorous clinical validation in an intended-use population. I treat [patients with] resectable stage II lung cancer, so I want to see how this test behaves in a cohort of 100 patients with resected stage II lung cancer; it's a simple requirement. I don't want an assay that's still in development. I want a rigorous, blinded statistical demonstration of its accuracy before I offer it to patients with stage II lung cancer. That kind of data are missing.
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