New Study Uncovers Significant Proportion of Potential False Negatives in Widely Used HPV DNA Test which could lead to Cervical Cancer
SAN DIEGO and ANN ARBOR, Mich., July 13 /PRNewswire-FirstCall/ -- Results from a study published by the University of Michigan have shown that as many as 15% of women in the study group determined to be negative for the presence of human papillomavirus (HPV) in the cervix, via the most commonly used test for HPV DNA, may actually be infected with the virus at clinically relevant viral loads. PCR-MS detected the presence of high-risk HPV in nearly half (46.7%) of women who tested negative by the Hybrid Capture 2 (HC2) test, which is standard of care in many countries. Approximately 9,000 American women are diagnosed with cervical cancer each year despite regular cervical screening. The study, titled, Development and Evaluation of a PCR and Mass Spectroscopy-based (PCR-MS) Method for Quantitative, Type-specific Detection of Human Papillomavirus, will be published in the September 2009 edition of Journal of Virological Methods. The assay used in this study is exclusively licensed by SEQUENOM (Nasdaq: SQNM).
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"We found that nearly half of the 75 women who had been called HPV-negative by the HC2 test had detectable levels of HPV DNA by the PCR-MS method," said Divya Patel, PhD, MPH, of the University of Michigan, one of the study investigators, and lead author of the recently published paper. "More importantly, because the PCR-MS method also measures the quantity of HPV relative to the number of human cells in the sample, or 'viral load,' we determined that about 15% of these samples had HPV loads comparable to the HPV loads found in women called HPV-positive by the HC2 test. While further work to define clinically meaningful HPV detection thresholds is required, our results suggest that a type-specific, quantitative PCR-MS based test may be an important advance in the early detection of cervical cancer."
Study Methodology
- 199 cervical scrapings from women who had been routinely screened for HPV DNA using the HC2 test, the most widely used clinical HPV test, and 77 tissue samples taken from tumors in confirmed cervical cancer patients were analyzed using a prototype assay developed by the late Dr. David Kurnit at the University of Michigan (subsequently, the assay has been exclusively licensed by SEQUENOM and known as the AttoSense(TM) HPV assay).
- Utilizing SEQUENOM's proprietary MassARRAY((R)) system that couples standard polymerase chain reaction (PCR) techniques with mass spectrometry (PCR-MS), study samples were simultaneously screened, genotyped and quantified for each of 13 HPV genotypes highly associated with cervical cancer.
Results Summary
- Nearly half (46.7%) of the 75 cervical scraping samples that were negative for high-risk HPV by the HC2 test were positive by PCR-MS, and approximately 15% of these samples contained a higher viral load than the clinically validated cut-off of the HC2 test.
- Eighteen (14.5%) of 124 cervical scraping samples that were positive by HC2 for high-risk HPV were negative by PCR-MS. In all these cases, degenerate DNA sequencing failed to detect any of the 13 high-risk HPV types included in the HC2 test, reflecting false positive results in the HC2 test.
"This is another example of how the precision of PCR-MS can be applied to solve important medical and scientific problems," said Charles Cantor, PhD, chief scientific officer of SEQUENOM. "Showing exceptional analytical performance in a proof-of-concept study is a significant step in designing an assay with great clinical performance.
