New data in women 15 to 55 years of age show that the GlaxoSmithKline (GSK) cervical cancer candidate vaccine induces an immune response to cancer-causing human papillomavirus types 16 and 18 in the bloodstream, which highly correlates to antibody levels in the cervico-vaginal secretions.
Furthermore, these antibodies to cancer-causing virus types 16 and 18 were detected and sustained for one year following completion of the vaccination course. These data were presented Tuesday at the AmericanCollegeof Obstetrics and Gynaecology (ACOG) annual meeting.
"Cancer-causing human papillomavirus is very effective at hiding from the immune system because it exists within the cervical epithelium, away from the bloodstream," said DrTino F Schwarz, Stiftung Juliusspital Wuerzburg, Germany, the lead study investigator. "This emphasizes the need for a cervical cancer vaccine to be effective in the cervix, at the site of infection. These data show there is a correlation between the vaccine inducing high antibody levels to the cancer-causing virus types in the bloodstream and the presence of antibodies in cervico-vaginal secretions, potentially providing antibodies where they are needed most."
This study is a subset of data from 90 women participating in a larger, open, age-stratified trial of 666 women between 15 to 55 years of age. Blood samples were collected at several time points after the first vaccine dose, and cervico-vaginal secretions were collected at 18 months. Samples were measured for immune response against cancer-causing virus types 16 and 18. Results from the study show that antibodies to cancer-causing virus types 16 and 18 in the cervico-vaginal secretions were detected across all age groups.
The results also show that antibody levels in the bloodstream were in the same range as those seen in a separate efficacy study of females 15 to 25 years of age, which indicate that the GSK cervical cancer candidate vaccine has shown to provide in the trials a 100 per cent efficacy for 5.5 years in preventing precancerous lesions due to cancer-causing virus types 16 and 18.
"These results are exciting, as they confirm that the higher the antibody levels in the blood, the higher the levels in the cervico-vaginal secretions, and present at the site of infection, where they are needed most," said James Tursi, MD, director of medical affairs, North Americaat GlaxoSmithKline. "These data are critical in helping us to better understand how our cervical cancer candidate vaccine formulated with the novel adjuvant, AS04, helps provide protection against cancer-causing virus types."