GlaxoSmithKline has announced the initiation of the first study of its kind designed to compare the immunogenicity of its cervical cancer candidate vaccine, Cervarix versus Gardasil.

The primary objective of the head-to-head trial is to compare the immune responses to HPV types 16 and 18 in US women 18 to 26-years-old. secondary objectives include evaluating the immune responses to HPV 16 and 18 in women 27 to 35-years-old and 36 to 45-years-old. In addition, the study will compare immune responses to other cancer-causing HPV types.

Initial study results are anticipated 12 months after study enrolment is completed, and extended follow up will continue for another 17 months.

"Vaccination to prevent cervical cancer may be the most significant healthcare breakthrough for women in our lifetime," said Dr Mark M Blatter, Medical Director of Primary Physicians Research in Pittsburgh, PAand study investigator. "This unprecedented trial, which will enrol more than 1,000 women, will provide the first scientific evidence to demonstrate how the two vaccines differ with respect to inducing strong and sustained immune responses in women who may be appropriate for vaccination."

Data published in Vaccine in August 2006 demonstrated GSK's cervical candidate vaccine, formulated with the proprietary adjuvant system AS04, induced higher antibody levels and more robust immune memory response compared to the same HPV vaccine composition conventionally formulated with aluminium hydroxide adjuvant alone. Furthermore, data published in The Lancet in April 2006 provided evidence that GSK's cervical cancer candidate vaccine demonstrated protection up to 4.5 years against persistent infection with HPV 16 and HPV 18 - the two most common cancer-causing HPV types - and protection from pre-cancerous lesions.

Protection was also demonstrated against infection with the third and fourth most prevalent cancer-causing types of HPV, namely types 45 and 31. Collectively, HPV types 16, 18, 45 and 31 are responsible for approximately 80 percent of cervical cancer cases globally.

"GSK is focused on protecting women from cervical cancer, a devastating disease that often strikes women in the prime of their lives," said Gary Dubin, vice president, HPV Vaccines, GSK. "By conducting this study, we hope to further the scientific understanding of the role of strong and sustained immune responses to HPV vaccination for the benefit of all women."