GSK Cervical Cancer Vaccine Demonstrates Protection For Up To 6.4 Years, Latest Data Shows
The vaccine protects against strains of the human papillomavirus (HPV) - 16 and 18 - which between them account for 70% of cervical cancer.2
The researchers, led by Dr Diane Harper, of the Dartmouth Medical School, New Hampshire, looked at protection against cell changes that can lead on to cervical cancer, known as CIN1, CIN2 and CIN3.
The researchers state: "Over a total of 6.4 years of follow-up, vaccine efficacy was 100% against HPV 16/18 associated CIN1+ (0 vs 15 cases) and 100% against CIN2+ (0 vs 9 cases)."
The study followed 776 women aged 15 to 25 years for up to 6.4 years, with the women being tested for HPV every six months. The new data is being presented at the American Society of Gynecologic Oncologists conference in Tampa, Florida.
These data also show that virtually all women in the study maintained high levels of antibodies against HPV 16 and 18 at every time point up to 6.4 years. These antibody levels were several times higher than those following natural infection over the extended period of time.
The study also confirmed substantial cross-protection against two other strains of HPV-45 and 31 - which are closely related to 16 and 18. Between them HPV 45 and 31 cause nearly 10% of cervical cancer globally.2 The vaccine showed 78% efficacy in preventing incident infection caused by HPV45, and 60% efficacy in preventing incident infection caused by HPV31.
The results also include safety data from up to 6.4 years which, the researchers state, was "comparable in both vaccine and placebo groups".
The findings were welcomed by Dr Anne Szarewski, Clinical Consultant at the Wolfson Institute of Preventive Medicine, London, and by Professor Margaret Stanley, Professor of Epithelial Biology at Cambridge University.
Dr Szarewski said: "This is excellent news, showing that Cervarix continues to give strong protection as the duration of follow up becomes longer. It is also important that cross-protection against other important HPV types continues to be shown, as this should make the vaccine more effective than was first thought."
Professor Stanley said: "The fact that efficacy persists out to 6.4 years is pretty significant. This is an important trial because the women in it were negative to all high risk types of HPV when the study started. This is the closest we are going to get to the group due to be vaccinated in the school programme - young women unexposed to the virus."
She added: "Getting this length of efficacy with 100% protection is important. It seems unlikely that a booster will be needed, although longer studies will be needed to confirm this."
Further data from the latest study is to be released in May at the European Society for Paediatric Infectious Diseases conference in Graz, Austria.
Notes
About the study
This was an extended follow-up (EFU) analysis of women who participated in the initial efficacy study of GSK's cervical cancer vaccine. The initial study was a double-blind, controlled trial of 1,113 young women between 15-25 years of age, randomised to receive three doses of Cervarix®, formulated with the AS04 adjuvant system, or three doses of a control substance (aluminium hydroxide) on a 0, 1 and 6 month schedule. The study follow-up started after the first dose of the vaccine.
This extended follow-up study looked at study endpoints for 776 women from the same cohort of women for a period of up to 6.4 years. The trial was conducted in 28 centres in Brazil, Canada and the U.S. and evaluated the efficacy, safety and immunogenicity of the vaccine for the prevention of infection with cancer causing virus types 16 and/or 18, and other cancer-causing virus types, as well as associated Pap smear abnormalities and cervical precancerous lesions.
In the extended follow up study, women were evaluated for the presence of human papillomavirus DNA by PCR using cervical samples and annual cervical cytology evaluations were performed. Women were referred for colposcopy following protocol guidelines. Women were also assessed for long-term immunogenicity and safety.
UK facts
Despite a highly successful screening programme in the UK, each year approximately 3,000 women develop cervical cancer and 1,000 women die of the disease. 3
Cervical cancer is the second most common cancer in women (after breast cancer) under the age of 35 in the UK.3 Cervical cancer can affect women of all ages but the peak age for diagnosis is 35-39. 4
HPV is very common. Up to 75% of sexually active women will be infected with HPV at some point in their lives. 5
National cervical screening policy in England is that women aged 25-49 are invited every three years, and women aged 50-64 every five years.
Overall across all ages from 25 to 64 some 4.3 million women were invited for cervical screening in England in 2006-07. Of these 3.2 million accepted and were screened. Some results could not be read and needed to be repeated. 6
Of the 3.1 million women aged 25- 64 who did have a result in 2006-07, 93.5% were negative. However 3.3% showed borderline changes, 1.9% showed mild dyskaryosis, 0.6% showed moderate dyskaryosis, 0.6% showed severe dyskaryosis and 0.1% showed cancer.
References
1. Harper D, Gall S, et al. HPV-007 Efficacy Abstract. "Sustained Immunogenicity and high efficacy against HPV-16/18 related cervical neoplasia: Long-term follow-up through 6.4 years in women vaccinated with CERVARIX (GSKS HPV 16/18 AS04 Candidate vaccine)" To be presented at: SGO's Annual Meeting on Women's Cancer. March 10, 2008 Tampa Convention Centre, Florida, USA.
2. Munoz N et al. Against which human papillomavirus types shall we vaccinate and screen? The international perspective. International Journal of Cancer 2004; 111(2):278-85.
3. Cancer Research UK statistics. (Accessed January 2008).
4. ONS. Registrations of cancer diagnosed in England (Series MB1 no.35). 2004.
5. Koutsky L. Epidemiology of genital human papillomavirus infection. The American Journal of Medicine1997; 102(5A):3-8.
6. Cervical Screening Programme England 2006-07. Department of Health Information Centre for Health and Social Care.
GlaxoSmithKline
GSK cancerului de col uterin vaccin demonstreazã de protecþie de pânã la 6,4 ani, Ultimele date aratã - GSK Cervical Cancer Vaccine Demonstrates Protection For Up To 6.4 Years, Latest Data Shows - articole medicale engleza - startsanatate