HPV Vaccine Reduces All Subtypes of HPV Disease

Zosia Chustecka

March 27, 2012

March 27, 2012 — Human papillomavirus (HPV) vaccination substantially reduced the risk for subsequent HPV disease in women who already had 1 bout of HPV-related disease, according to a study published online today in BMJ.

"These are, to our knowledge, the first results in vaccinated women who have undergone treatment for HPV-related disease," write the authors, headed by Elmar Joura, MD, from the Medical University of Vienna in Austria.

The data come from a subgroup of women who participated in trials of the quadrivalent HPV vaccine Gardasil (Merck & Co).

Women who had HPV infection at the time of vaccination and who developed cervical, vulvar, or vaginal HPV disease had a substantially reduced risk of developing subsequent HPV-related disease after the first definitive treatment.

HPV vaccination substantially reduced the risk for subsequent HPV disease — not only that caused by the 4 viral strains in the quadrivalent vaccine (HPV subtypes 6, 11, 16, and 18), but also that caused by other strains of HPV-related disease.

This study "reinforces much of what we already know about the protective properties of the quadrivalent vaccine, including cross-protection against nonvaccine HPV types and vaccine benefit despite HPV exposure," writes Jane Kim, assistant professor of health decision science at Harvard School of Public Health, Boston, Massachusetts, in an accompanying editorial.

Subgroup of Women

The study analyzed data collected from 2 large company-sponsored placebo-controlled trials of Gardasil, known as FUTURE I and FUTURE II. Together, they involved 17,622 women 15 to 26 years of age who were randomized to receive 3 doses of the quadrivalent HPV vaccine or placebo. They were subsequently followed for approximately 4 years.

The analysis focused on a subgroup of 2054 women who participated in these trials and who were subsequently treated for cervical, vulval, or vaginal disease.

More than half of this subgroup (1350 women) underwent cervical surgery (which included any method used to treat cervical disease) — 763 from the placebo group and 587 from the vaccine group.

The researchers calculate that the incidence of any subsequent HPV-related disease in the cervix was 6.6 in the vaccine group and 12.2 in the placebo group — a reduction of 46.2% with vaccination.

When only high-grade disease of the cervix was considered, this reduction is even greater; vaccination reduced the risk for any subsequent high-grade disease of the cervix by 64.9%.

The remaining women in the subgroup (229 in the vaccine group and 475 in the placebo group) were subsequently diagnosed with either genital warts or vulvar or vaginal intraepithelial neoplasia. Here, the incidence of any subsequent HPV-related disease was 20.1 in the vaccine group and 31.0 in the placebo group — a reduction of 35.2% with vaccination.

This was primarily driven by a reduction in the incidence of genital warts (63% reduction after vaccination), the authors note.

In all cases, the reduction was for all subtypes of HPV-related disease, including strains of HPV virus that were not included in the vaccine.

New Findings Welcome

These findings are "welcome," Dr. Kim writes.

This study "moves us closer to understanding the full scope of benefits from HPV vaccination by showing for the first time that vaccine protection against disease can endure beyond the management of HPV-related disease in women already vaccinated," she adds.

However, Dr. Kim takes issue with some of the conclusions drawn by the authors.

This study corroborates previous findings that the benefits of vaccination are not limited to the primary target group of young sexually naïve girls, Dr. Kim explains. The findings highlight the importance of vaccinating at an early age, when exposure to HPV is minimal, to maximize protection against all HPV types targeted by the vaccine.

Most important, she adds, this study examines a unique subgroup of women who were vaccinated before their first treatment for HPV-related disease. The authors suggest that these results could be generalized to women who are considering HPV vaccination after treatment for HPV-related disease, but Dr. Kim disagrees, and suggests that more data are needed.

"Only surveillance of vaccinated populations in the real world can provide clear evidence of the effectiveness of the vaccine in women who have been treated before vaccination," Dr. Kim writes. "As we await this information, it is important to emphasize to providers and decision makers that generalizations of study findings are premature."

The study was funded by Merck & Co. Dr. Joura reports receiving advisory board fees from Merck; and lecture fees from Merck, Sanofi Pasteur MSD, and GlaxoSmithKline. Several coauthors are employees of Merck & Co, and several report receiving funding from Merck and GlaxoSmithKline for HPV vaccine studies, and from other pharmaceutical companies. Dr. Kim has disclosed no relevant financial relationships.

BMJ. Published online March 27, 2012. Abstract, Editorial

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