HPV Serum Antibodies Predict Survival in Oropharyngeal Cancer Patients

June 18, 2015

Detection of antibodies against HPV16 in the blood of patients with HPV-positive oropharyngeal carcinoma correlates with improved survival.

Detection of antibodies against human papillomavirus type 16 (HPV16) in the blood of patients with HPV-positive oropharyngeal carcinoma correlates with improved overall survival (OS) and progression-free survival (PFS), according to the results of a new study published in Clinical Cancer Research.

Because oropharyngeal cancer patients have different levels of HPV16 antibodies, the study suggests that these immune reactions may be due to different biological interactions of the patient’s immune system and the tumor. If validated, the levels of these antibodies may be used as prognostic indicators in these patients.

In this study, Erich M. Sturgis, MD, professor in the department of head and neck surgery at the University of Texas MD Anderson Cancer Center in Houston, and colleagues examined the potential prognostic relevance of HPV16 antibody levels in HPV-positive oropharyngeal cancer patients. Prior studies have suggested that those with HPV-positive tumors have better responses to therapy and better survival outcomes compared with patients with HPV-negative oropharyngeal cancer. One recent study reported a 68% reduced risk of death among patients who tested positive for a specific HPV antibody compared with those in whom the antibody was not detected.

Sturgis and study coauthors analyzed blood samples from 209 patients with previously untreated oropharyngeal carcinoma; the HPV16 tumor status was known and 96 patients had HPV-positive disease. Patients had blood drawn prior to starting treatment, 6 weeks after the end of their initial treatment, and at 6-month intervals for as long as 3 years. The samples were screened for six HPV16-associated antibodies.

Patients who tested positive for three of the six antibodies-the E antibodies against the E1, NE2, and E6 proteins-had improved OS and PFS compared with patients who tested negative. The 5-year estimated OS among patients positive for any of the three E antibodies was 87.4% vs 42.2% for patients who did not have any detectable E antibodies (P < .001).

PFS was 82.9% for patients positive for any of the E antibodies and 46.1% for those who had no detectable E antibodies (P < .001). Those who tested positive for all three E antibodies had an 80% reduced risk of death and a 70% reduced risk of disease progression.

These E proteins are known antigens, functioning in HPV-related carcinogenesis.

The presence of antibodies against two viral capsid proteins-L proteins-did not correlate with better patient outcomes

“If this testing became commercially available it could not only be used as a means of identifying people who are at risk for oropharyngeal and other HPV cancers, but may also allow identification of HPV-related oropharyngeal cancer patients at greater or lower risk for cancer recurrence and death,” said Sturgis in a statement.

According to the study, detecting HPV16 antibodies in patients’ blood samples may be a noninvasive way to identify HPV16-positive tumors. Additional blood-based biomarkers may improve the validity of the prognostic value of these antibodies, stated the authors. Prospective trials are needed to validate the results of this study.