Merck, the manufacturer of the quadrivalent HPV vaccine Gardasil, already being administered in many countries to girls as young as 12 to help prevent cervical cancer, has announced findings of a trial that shows it is also effective for women as old as 45.
The drugmaker announced details of an investigational study where Gardasil reduced the rate of infection due to four strains of sexually transmitted human papillomavirus (HPV) in women up to the age of 45, at the 24th International Papillomavirus Conference (IPC) in Beijing, China, yesterday, Sunday November 4th.
Gardasil is a quadrivalent, recombinant vaccine designed to reduce infection due to HPV strains 6, 11, 16 and 18 and trials have already shown it be to effective for girls and women aged 9 to 26 years in the prevention of cervical cancer, precancerous or dysplastic lesions, and genital warts. In trials it was shown that by protecting against the four HPV strains that cause most of the diseases, it prevented 70 per cent of cervical cancer cases and 90 per cent of genital warts cases.
In the latest international, multi-center, trial involving more than 3,800 women, the three dose vaccine was also shown to prevent 91 per cent of persistent infection, low-grade cervical abnormalities and pre-cancers, as well as external genital lesions caused by the four strains of HPV in women aged 24 to 45.
The women in the trial had no history of genital warts; hysterectomy; LEEP (loop electrosurgical excision procedure) or biopsy-diagnosed cervical HPV disease in the five years previous to enrollment. They were also all free of infection from at least one of the four HPV strains when they were enrolled in the study and remained free of infection from the same strains when they finished the three doses of vaccine or placebo.
Dr Eliav Barr, executive director of Biologics Clinical Research and head of the HPV Vaccine Program, Merck Research Laboratories said in a press statement that:
“Women remain at significant risk for acquiring HPV infections and developing HPV-related diseases throughout their lifetime.”
“These data build on the clinical program for GARDASIL and will help us to understand the potential benefit that GARDASIL may have in women through age 45,” added Barr.
The drugmaker will be submitting the results of the trial with an application to the US Food and Drug Administration (FDA) before the end of the year to extend approved indication of the vaccine for women up to 45. The FDA approved Gardasil in June 2006 and the vaccine is recommended for use in the US for girls and women aged 11 to 26 by the Centers for Disease Control and Prevention (CDC).
Researchers tracked the incidence of persistent infection, cervical intraepithelial neoplasia (CIN) and external genital lesions caused by the four HPV strains (6, 11, 16 and 18) and diseases caused by HPV 16 and 18.
The results showed that:
- There were 4 cases of of persistent infection, CIN or external genital lesions (genital warts and vaginal and vulvar lesions) caused by HPV 6, 11, 16 or 18 in the vaccine group compared to 41 cases in the placebo group.
- This equated to a 91 percent reduction in incidence (at 95 per cent confidence interval, or CI) over an average follow up of 1.65 years.
- There were 4 cases of of persistent infection, low-grade cervical abnormalities and pre-cancers, and external genital lesions caused by HPV types 16 and 18 alone, in the vaccine group, and 23 cases in the placebo group.
- This equated to a 83 per cent prevention rate (at 95 per cent CI) for diseases caused by HPV types 16 and 18 alone.
- The vaccine prevented 100 per cent of persistent infections, external genital lesions, and low-grade cervical abnormalities and pre-cancers, caused by HPV strains 6 and 11.
- It also reduced abnormal Pap test results related to HPV 16 and 18 by 94 percent (at 95 per cent CI).
- The most common adverse events related to the injection site (redness, pain, pruritis, swelling, warmth) and were higher in the vaccine than the placebo group (76.4 versus 64.2 per cent).
Gardasil is widely available in the US, and all the country’s 55 immunization programs have adopted it. In addition to the US, the vaccine is approved in 85 countries throughout the world, including all of the European Union, Australia, Brazil, Canada, Mexico, New Zealand and Taiwan.
HPV is a common infection, and it is estimated that some 20 million people in the US have it and that 80 per cent of women will have acquired it by the age of 50. In most people HPV is self-limiting and disappears by itself. But for some women, the higher risk HPV strains can lead to cervical cancer if untreated.
Nearly half a million cases of cervical cancer are diagnosed worldwide every year, and 240,000 women die from it each year. It is the second most common cause of cancer death in women worldwide.
Click here for prescribing information on Gardasil (from the manufacturer, PDF file).
Written by: Catharine Paddock