GSK’s cervical cancer vaccine, Cervarix®, is superior to Gardasil® in generating a significantly greater antibody response at seven months in women aged 18-45 against the two main cancer causing human papillomavirus (HPV) subtypes 16 & 18. These results, from the first of its kind, head-to-head study, will be presented at the 25th International Papillomavirus Conference (IPV) in Malmö, Sweden.
The comparative study looked at two key measures of immune response, neutralising antibodies and memory B cells, believed to play an important role in how well a vaccine will protect women from HPV infection and subsequent cervical cancer over the long term. Although, it should be noted that the minimal antibody level associated with protection against the early stages of cervical cancer are still unknown.
The trial, which was designed to show non-inferiority between the two vaccines, showed antibody levels for Cervarix® were more than two times higher than those for Gardasil for HPV type 16 and more than six times higher for HPV type 18 at seven months in all women (aged 18-45). These results were statistically significant (p<0.0001).
Results showed that at seven months Cervarix® induced 2.7 times more memory B cells than Gardasil® for both HPV types 16 and 18 (p<0.0001) in women with no detectable B-cell response before vaccination. These results are very exciting as memory B cells are critical in secreting antibodies, thus maintaining the body’s first line of defence against infection. Memory B cells also help the body to swiftly generate high levels of antibodies if exposed to the virus in the future.
Dr. Anne Szarewski, Clinical Consultant at the Wolfson Institute of Preventive Medicine commented: “These results are very promising. In September 2008, the Government launched the cervical cancer vaccination programme, using Cervarix® to, vaccinate girls aged 12–13 and 17–18 against HPV. This study offers evidence for the first time that the two available HPV vaccines do not generate the same level of response against HPV 16 and 18, the two most common cancer causing virus types. Vaccines need to provide long-term protection, as women remain vulnerable to infection and potential development of related lesions throughout their life.”
Tolerability and safety results of the head-to-head study showed acceptable results for both vaccines. Cervarix® did induce more localised reactions (e.g. redness and swelling at the site of injection); however, these were short-lived, with a median duration of 3.3 days or less, and did not negatively affect patient compliance. The full results from this comparative study will be published in a peer reviewed journal.
Follow-up results from a second placebo controlled study, Immunogenicity and safety of HPV-16/18 AS04-adjuvanted vaccine up to 7.3years, designed to specifically evaluate the immunogenicity and safety of Cervarix® showed that the vaccine provided high (11-13 fold above natural infection levels) and sustained antibody levels for up to 7.3 years after vaccination, the longest follow-up reported to date for any licensed cervical cancer vaccine2. In the study, Cervarix® demonstrated a favourable safety/tolerability profile
