NEW YORK (Reuters Health) – GlaxoSmithKline’s Cervarix vaccine against human papillomavirus (HPV) is significantly more immunogenic than Merck’s Gardasil in HIV-infected women, though both are highly immunogenic, according to Danish and German researchers.
In men the difference was less pronounced, they found.
As Dr. Lars Toft told Reuters Health by email, “in HIV-infected women, the bivalent HPV vaccine (Cervarix) provides significantly higher levels of neutralizing antibodies against HPV-16 and -18 when compared to the quadrivalent HPV-vaccine (Gardasil).”
“These results,” he said “are similar to those previously reported in healthy women but it is the first time that the two HPV-vaccines have been compared directly in people with HIV. In HIV-infected men, the results are a bit more ambiguous. However, that is not of great clinical importance since only the quadrivalent vaccine is approved for use in men.”
In a paper online November 23 in the Journal of Infectious Diseases, Dr. Toft of Aarhus University Hospital in Aarhus, Denmark, and colleagues note that persistent infection with oncogenic HPV genotypes cause approximately 600,000 cancers worldwide every year and people with HIV are at increased risk.
In fact, the U.S. and Australia are among countries that now recommend routine HPV-vaccination of HIV-infected individuals, but little is known about immunity induced in this group.
To investigate, the researchers randomized 92 men and women to receive three doses of Cervarix or Gardasil at 0, 1.5 and 6 months. Immunogenicity was monitored for up to 12 months.
At 7 and 12 months, anti-HPV-18 antibody titers were higher in the Cervarix group. No significant between-group differences were seen in anti-HPV-16 antibody titers.
Women given Cervarix had higher HPV-16/-18 antibody titers compared to men. There were no such gender-specific differences in the Gardasil group.
There were no serious adverse events but mild injection site reactions were significantly more common with Cervarix (91.1% versus 69.6%).
The researchers note that the study “was not powered to compare the two vaccines on clinical endpoints and with only 15 female subjects per vaccine group, it was not powered to detect gender-related differences.” In addition, “the significance of the magnitude of neutralizing antibody titers remains elusive.”
Nevertheless, they say, “Our study emphasizes the need to carefully design and interpret clinical studies with enhanced focus on differences between male and female participants.”
Dr. Toft went on to stress that, “From our small study, we cannot possibly make any reasonable comments as to which vaccine would be more suitable among HIV-infected women. Only a head-to-head vaccine trial designed with clinical endpoints could determine that.”
“We can say,” he concluded, “that both vaccines are highly immunogenic and likely to protect HIV-infected women against infection with the HPV types that most frequently cause cervical cancer. Also, the quadrivalent vaccine is likely to protect HIV-infected men against infection with the HPV types that most frequently cause anal cancer.”
The study was funded by various Danish foundations and by Aarhus University and the Danish Medical Association. One of the authors has received royalties from Loyola University Chicago related to sales of Cervarix, and two others have receives lecture fees from GSK.
J Infect Dis 2013.