Blood Plasma Assay for Circulating Tumor HPV DNA

(“liquid biopsy” for HPV related squamous cell carcinoma/NavDx)

What is the Blood test for Circulating Tumor HPV DNA?

A test for circulating tumor HPV DNA (ctHPV DNA) is designed to detect the presence of human papillomavirus (HPV) DNA in the blood of patients with HPV-driven oropharyngeal squamous cell carcinoma (OPSCC). HPV is a significant risk factor for developing OPSCC, and its presence in tumor tissue can indicate the underlying cause of the cancer.

One company’s test, marketed under the trade name “NavDx,” works by isolating circulating tumor DNA from a blood sample. Since cancer cells can release DNA fragments into the bloodstream, the ctHPV DNA test analyzes these fragments specifically for HPV genetic material. The detection of ctHPV DNA is useful for several clinical applications:

1. Diagnosis: Pretreatment ctHPV DNA is detectable in ~90–97% of patients with HPV-positive oropharyngeal cancer. Sensitivity* is lower for cervical cancer (pooled sensitivity ~36%) and varies by the size and extent of disease.

2. Treatment response monitoring: ctHPV DNA levels correlate with tumor burden and decline with effective therapy. Rapid early clearance (≥95% reduction) during treatment predicts radiographic response and favorable outcomes.

3. Minimal residual disease (MRD) detection: Persistent or detectable ctHPV DNA after surgery or chemoradiotherapy is associated with heightened recurrence risk.

4. Post-treatment surveillance: Two consecutively positive ctHPV DNA tests during surveillance carry a PPV* of 94% and NPV* of 100% for disease recurrence, with a median lead time of 3.9 months before clinical detection. Patient-level estimates from a multi-center study of 1,076 patients showed PPV* of 95% and NPV* of 98%.

5. Early detection (this remains investigational): Emerging data suggest ctHPV DNA may be detectable in plasma up to 7.8 years before clinical diagnosis of HPV-positive oropharyngeal cancer, with 79% sensitivity* and 100% specificity*.

The plasma ctHPV DNA test is a valuable tool for diagnosing and managing HPV-driven oropharyngeal squamous cell carcinoma. It is new, however, and its application to patient care has yet to be understood fully. The College of American Pathologists 2025 guideline update notes that while ctHPV DNA testing is increasingly used clinically for surveillance, no survival benefit from early detection has yet been demonstrated, and ctHPV DNA should not be used to guide clinical care outside of a clinical trial at this time. Standardization of assay methodologies and prospective validation remain ongoing priorities

Definitions:

PPV = positive predictive value = The percentage of positive test results where the disease is truly present.

NPV = negative predictive value = The percentage of negative test results where the disease is truly absent.

Sensitivity = The percentage of test results that detect the disease when the disease is truly present.

Specificity = The percentage of test results that do not detect the disease when the disease is truly absent.