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Gardasil 9 efficacious in preventing HPV

The nine-valent HPV vaccine, Gardasil 9, safely and effectively protects against HPV infection and long-term disease, and may potentially reduce 90% of cervical cancers worldwide, according to phase 3 study results published in The Lancet.

The two-valent Cervarix (GlaxoSmithKine) and the quadrivalent Gardasil (Merck; qHPV) effectively protect against disease caused by HPV 16 and 18 — which alone are responsible for an estimated 70% of all cervical cancers — but not all HPV types associated with cancer, according to the researchers. Recently, scientists developed an improved 9-valent vaccine (Gardasil 9, Merck; 9vHPV) to target five more HPV types associated with cervical cancer (HPV 31, 33, 45, 52 and 58) in addition to HPV 6, 11, 16 and 18, which were already targeted in qHPV.

“Based on epidemiological studies, the 9vHPV vaccine could prevent approximately 90% of cervical cancer, 90% of HPV-related vulvar and vaginal cancer, 70 to 85% of high-grade cervical disease in females, and approximately 90% of HPV-related anal cancer and genital warts in males and females worldwide,” Anna R. Giuliano, PhD, director of the Center for Infection Research in Cancer at Moffitt Cancer Center, said in a press release.

Giuliano and colleagues conducted a double blind, immunogenicity and safety study to determine the efficacy of 9vHPV for up to 6 years after the initiation of the vaccine, as well as antibody responses for more than 5 years. They recruited 14,215 women aged 16 to 26 years from 105 sites in 18 countries. Participants had no history of abnormal cervical cytology or abnormal cervical biopsy results and no more than four lifetime sexual partners.

Between Sept. 26, 2007, and Dec. 18, 2009, participants were randomly assigned 1:1 to receive three intramuscular injections of either 9vHPV (n = 7,106) or qHPV (control; n = 7,109) vaccine over the course of 6 months. The researchers examined participants’ gynecological exams for evidence of infections or diseases, and tested their blood sera for antibody levels against HPV.

The researchers found that 9vHPV was 97.4% effective at preventing incidences of high-grade cervical disease (cervical intraepithelial neoplasia grade 2 or 3, adenocarcinoma in situ or invasive cervical carcinoma), vulvar disease (vulvar intraepithelial neoplasia grade 2 or 3 or vulvar cancer) and vaginal disease (vaginal intraepithelial neoplasia grade 2 or 3 or vaginal cancer) related to HPV 31, 33, 45, 52 and 58. The incidence rate for these three diseases was 0.5 cases per 10,000 person-years for the 9vHPV group and 19 cases per 10,000 person-years for the qHPV group. The 9vHPV vaccine also greatly reduced the risk for HPV 31, 33, 45, 52 and 58-associated cervical cell abnormalities, biopsies and definitive therapies.

From 1 month to 3 years after vaccination, HPV 6, 11, 16 and 18 geometric mean titers were noninferior in the 9vHPV group compared with the qHPV group, indicating similar antibody protection. There were no significant differences in serious adverse events between the two vaccines.

“We’re on the verge of a dramatic change that will positively affect all individuals, particularly women, in the United States,” Warner K. Huh, MD, coauthor from the division of gynecologic oncology at the University of Alabama at Birmingham, said in a separate news release.

“With this new vaccine, there is a very legitimate opportunity to wipe out cancers that are caused by HPV, particularly cervical cancer in women,” he added.

“Looking forward, with widespread vaccination, it is highly likely that cervical cancer will evolve into historical interest only, and screening, like Pap smears, might go away altogether,” he continued. “HPV vaccines are one of the most scrutinized vaccines ever, but multiple studies have demonstrated the vaccine to be safe and well-tolerated.”

Attaining widespread use of 9vHPV among young women will be challenging however, Huh noted.

In an accompanying editorial, Lynette Denny, MD, PhD, from the department of obstetrics and gynecology at the University of Cape Town in South Africa, wrote that while the findings of Huh and colleagues prove that the 9vHPV vaccine is safe and effective, there are several essential issues that need to be addressed, including cost-effectiveness, affordability, implementation of the vaccine, functional health systems and good adherence.

“The extra protection provided by the 9vHPV is unlikely to make any difference to the lives of women in [low-income and middle-income countries] if access is limited by cost, logistical, political and health-system constraints, despite attempts by many societal sectors to bring HPV vaccination to [low-income and middle-income countries],” she noted. “It is essential that the international community pay attention to the gross inequities that exist in cervical cancer prevention efforts, and although the research presented in this paper is robust, credible and done to the highest standards, it might still be far from providing an intervention that will save the lives of women in [low-income and middle-income countries].” – by Alaina Tedesco

Disclosures: Huh reports he has received consultant fees from Merck. Denny reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.