The immune response against the virus that causes cervical cancer is stronger and sustained following vaccination with GlaxoSmithKline's (GSK) candidate HPV vaccine formulated with the innovative AS04 adjuvant compared to using the same vaccine formulated with a conventional aluminium salt adjuvant. 1
Data from the first studies to directly compare two different formulations of GSK's HPV vaccine has revealed that the antibody response induced by the vaccine formulated with the innovative AS04 adjuvant was higher, compared to the same vaccine formulated with a conventional aluminium salt adjuvant. This enhanced immune profile observed with the AS04 formulation was shown to persist for at least 3.5 years post-vaccination. 1
Furthermore, these data, published in Vaccine, showed that the AS04 adjuvanted vaccine also induced a more robust immune memory response - specifically, the AS04 formulation elicited an increased number (2.5 to 5.2 fold) of HPV 16/18 specific memory B-cells - compared to that observed after vaccination with the same vaccine formulated with a conventional aluminium salt adjuvant.
In previously published studies, GSK's HPV vaccine, formulated with the innovative AS04 adjuvant, has demonstrated sustained efficacy up to 4.5 years against HPV 16/18 infections, associated abnormal cytology and precancerous lesions (CIN). 2,3
Clinical trials are currently ongoing to determine the duration of protection that results from HPV vaccination. They aim to establish whether the higher antibody levels seen following vaccination with the AS04 adjuvanted HPV vaccine will have a positive impact on long term protection.
Dr Philippe Monteyne, Head of Global Vaccine Development of GSK Biologicals, said: "For a HPV vaccine to be effective, it must induce a strong immune response and provide protection that lasts. These new data demonstrate a genuine immunological benefit with the AS04 adjuvant by contributing to a strong and sustained vaccine-induced immune response of high quality."
What is an adjuvant?
The word adjuvant comes from the Latin word adjuvare which means 'to help'.
Adjuvants are substances, which when used in combination with antigens in vaccines, enhance the immune response. The use of adjuvants in vaccines is very common. Vaccines have conventionally been formulated with aluminium salt as the adjuvant.
About GSK's AS04 adjuvant
GSK's candidate HPV vaccine is formulated with the innovative adjuvant AS04. AS04 is composed of aluminium salt and monophosphoryl lipid A (MPL). MPL is an immunostimulant, capable of directly activating key immune mechanisms. The combination of aluminium salt and MPL has been shown, in these studies, to further enhance the immune response to antigens included in the vaccine compared to aluminium salt alone.
About the studies
In these studies, GSK's HPV vaccine, formulated with the innovative AS04 adjuvant, and the same vaccine formulated with a conventional aluminium salt adjuvant were compared to assess the quality of the immune response generated after vaccination.
In human studies, subjects received a three-dose course (at 0, 1 and 6 months) of GSK's HPV vaccine formulated with either the innovative AS04 adjuvant or a conventional aluminium salt adjuvant. Following vaccination, antibody levels and immune memory B-cells were measured.
Results in human subjects showed that enhanced antibody levels induced by the AS04 adjuvanted HPV vaccine were 1.5 and 2.1 times higher for HPV 16 and HPV 18 respectively, at 3.5 years post-vaccination, compared to those induced following vaccination with the same vaccine formulated with a conventional aluminium salt adjuvant.
The studies also demonstrated the ability of the AS04 adjuvanted vaccine to increase the number of immune memory B-cells. One month following completion of a three-dose course of GSK's HPV vaccine formulated with the innovative AS04 adjuvant, observed numbers of memory B-cells were 2 and 3.6 times higher for HPV 18 and HPV 16 respectively than those observed following vaccination with the same vaccine formulated with a conventional aluminium salt adjuvant. Recent observations have indicated that immune memory B-cells play a key role in the persistence of antibody levels following vaccination.
Full results of the studies may be viewed online at:
sciencedirect or Vol. 24 of Vaccine, publication date 14 August 2006.
About GSK's candidate HPV vaccine
GSK's HPV vaccine has been developed to prevent infection and precancerous lesions caused by the two most common HPV types associated with cervical cancer, HPV 16 and 18. In addition, GSK's candidate HPV vaccine has shown protection against incident infection with the third and fourth most common HPV types associated with cervical cancer, HPV 45 and 31. 2,3 HPV types 16, 18, 45 and 31 are collectively responsible for approximately 80 per cent of cervical cancers globally. 2,3
GSK submitted a marketing application for its HPV vaccine to the European Agency for the Evaluation of Medicinal Products (EMEA) in March 2006.
An ongoing Phase III clinical trials programme involving more than 30,000 women worldwide continues.
About HPV and cervical cancer
Cervical cancer and precancerous lesions together represent a significant health and psychological burden for women in the UK. 4-9
In the UK each year, almost 3,000 new cases of cervical cancer are reported 5 and there are more than 1,000 deaths. 4 It is the second most common cancer in women under the age of 35 years.5
Cervical cancer is not hereditary. It is caused by high risk types of human papillomavirus (HPV). Two high risk types of the virus, HPV 16 and 18, together cause approximately 70 per cent of cervical cancers. 12
Anyone who has had a sexual relationship is at risk of infection with HPV, as it is very common and easily transmitted through skin to skin contact in the genital area. 13-14 Up to 80 per cent of sexually active women will be infected with a type of HPV at some point in their lives. 16-17
Most infections will be cleared naturally but, if infection persists, women are at risk of developing cervical cancer. It is not possible to predict which women with persistent infection will go on to develop precancerous lesions and/ or cancer. 17
Risk of exposure to high risk HPV can continue throughout a sexually active woman's life 18 and prior HPV infection may not always provide sufficient immunity to protect against subsequent infections. 12, 13, 19, 20
Detection and treatment of precancerous lesions through screening has reduced cervical cancer incidence and mortality in the UK, highlighting the importance of attending regular cervical screening. 6
It has been estimated that without a screening programme, up to 5,000 more UK women would die each year from cervical cancer. 21
About GlaxoSmithKline and GlaxoSmithKline Biologicals
GlaxoSmithKline - one of the world's leading research-based pharmaceutical and healthcare companies - is committed to improving the quality of human life by enabling people to do more, feel better and live longer. For company information please visit gsk.
GSK Biologicals (GSK Bio), one of the world's leading vaccine manufacturers, is headquartered in Rixensart, Belgium, where the majority of GlaxoSmithKline's activities in the field of vaccine research, development and production are conducted. GSK Bio employs more than 1,500 scientists, who are devoted to discovering new vaccines and developing more cost-effective and convenient combination products to prevent infections that cause serious medical problems worldwide.
In 2005, GSK Bio distributed more than 1.2 billion doses of vaccines to 165 countries in both the developed and the developing world, an average of more than 3 million doses per day.
References
1. Giannini SL et al. Vaccine 2006
2. Harper D et al. Lancet 2006; 367: 1247-1255
3. Harper D et al. Lancet 2004;364:1757-65
4. Ferlay J et al. Globocan 2002: Cancer incidence, mortality and prevalence worldwide. IARC Cancerbase No. 5. Version 2.0, IARC Press, Lyon, 2004. www.depdb.iarc.fr/globocan/GLOBOframe.htm
5. CancerStats Jan 2003
6. Cervical Screening Programme England 2004/5. National Statistics Bulletin 2005/09/HSCIC
7. Office of National Statistics. Cancer registration statistics 2002
8. Rogstad KE. BJOG 2002; 109 (4):364-8
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11. Bosch FX et al. J Clin Pathol 2002; 55: 244-65
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13. Baseman J and Koutsky L. J Clin Virol 2005
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15. Koutsky L. American Journal of Medicine 1997; 102 (5A); 3-8
16. Moscicki A-B et al. J Pediatr 1998: 132: 277-84
17. Choma K. Am J Nursing 2003; 103(2): 42-50
18. Grainge et al. Em Infect Dis 2005; 11 (11): 1680-1685
19. De Jong A et al. Cancer Res 2004; 64: 5449-55 20. Franco EL and Harper DM. Vaccine 2005; 23: 2388-94
21. Peto et al. Lancet 2004 (July 17); 364: 249-256
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