Hillary Sloane, Senior Director of Medical Affairs at Haystack Oncology, Quest Diagnostics, summarizes study data showcasing a new way to monitor treatment response and detect recurrence in HPV-associated head and neck cancer, presented at ASCO 2026.
The following transcript has been edited for clarity.
My name is Hillary Sloan, and I lead clinical development for Haystack MRD by Quest Diagnostics.
Haystack MRD is a tumor-informed blood test designed to detect minimal residual disease (MRD), by measuring circulating tumor DNA (ctDNA) in the blood. At the American Society of Clinical Oncology, or ASCO, 2026 annual meeting, we presented new data across multiple tumor types, including gastric cancer and head and neck cancer. And today, I'd like to highlight the study in head and neck cancer, which was conducted in collaboration with Doctors Nishant Agarwal and Ari Rosenberg at the University of Chicago.
This was a study focused on patients with HPV-associated oropharyngeal squamous cell carcinoma. Many of these patients have favorable outcomes, but treatment can be intensive and associated with substantial long-term side effects. For these patients, better tools are needed to understand who's best responding to treatment, which patients are most likely to recur, and importantly, to be able to detect that recurrence early. Existing data suggests that ctDNA could help refine response assessment, support response adaptive treatment strategies, and improve surveillance after therapy for these patients.
In the study we presented at ASCO, we evaluated two related but distinct blood-based biomarkers: tumor-informed ctDNA, which tracks patient-specific tumor mutations, and circulating tumor HPV DNA, or ctHPV DNA, which tracks viral DNA from the HPV virus that's driving the cancer. Both were measured using next-generation sequencing-based assays from Haystack Oncology by Quest Diagnostics.
Our goal was to compare these two approaches within the same patients over time and determine whether they provide overlapping or complementary information. Both assays demonstrated 100 percent detection prior to treatment, and across 85 longitudinal samples collected during treatment and in the surveillance setting, results were highly concordant with an overall percent agreement of 91 percent.
When both analytes were present, changes in ctDNA and ctHPV DNA were highly aligned, but ctHPV DNA was consistently detected at higher absolute levels. And in cases where ctHPV DNA was positive but ctDNA was negative, this occurred during neoadjuvant treatment monitoring and appeared to reflect earlier clearance of ctDNA, with ctHPV DNA clearance lagging by several weeks to months.
Taken together, these findings support the potential role of blood-based biomarkers in the treatment of HPV-associated head and neck cancers, and both tumor-informed ctDNA and ctHPV DNA are highly concordant but may provide distinct information about treatment response over time. Ongoing analyses will really define how these tools can optimally be integrated into response assessment, treatment adaptation, and surveillance strategies.
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