New research suggests that Gardasil, the vaccine developed to protect women against some strains of the cervical cancer-causing human papilloma-virus (HPV), is also effective in preventing HPV infections in men.
The clinical trial, conducted by researchers from the University of California, San Francisco (UCSF) with financial backing from Gardasil manufacturer Merck, may help to get the vaccine approved for use in men in Canada.
Results of the trial were presented at the 25th annual International Papillomavirus Conference in Sweden in May. Lead researcher Joel Palefsky noted that Gardasil appears slightly less effective in preventing HPV infection in men than in women.
“The numbers right now look not quite as good as the girls’ but still very, very good,” says Palefsky. “The vaccine was nearly 100 percent effective [in women] so you obviously can’t do better than that.”
Palefsky says the vaccine would still make an effective preventative health tool for everyone because the same strains of HPV that cause most cervical cancers in women also cause a majority of anal cancers in men.
“They’re entirely the same,” he says. “That’s why we’re optimistic that if boys do get vaccinated with the same vaccine that girls are using, it should prevent a substantial number of anal cancers.”
HPV is sexually transmitted. The US Centers for Disease Control suggests that gay men are as many as 17 times more likely to develop anal cancer than are heterosexual men.
“On a per-individual basis the risk is clearly much higher in MSM than the general population,” says Palefsky. “That’s presumably due to anal sex, though we also know that you don’t have to have anal sex to get anal HPV infection.”
In an email to Xtra, Vincent Lamoureux, a spokesperson for Merck, declined to say if the company was preparing a Supplemental New Drug Submission application to Health Canada to get the vaccine approved for men.
“As a matter of policy we cannot comment on our communications with Health Canada since this is proprietary information,” wrote Lamoreux.
In 2006 Health Canada approved Gardasil for use in girls and women aged nine to 26. But even though the vast majority of girls and women who become infected with HPV get the virus from men, and even though Gardasil would likely protect gay men from increased cancer risks, a Health Canada spokesperson says approval of Gardasil for use in men must still be secured through traditional channels.
“Health Canada does not rely on publications to authorize a new product or a new indication for any product,” spokesperson Gary Scott Holub wrote in an email. “The main reliable evidence must come from properly designed and well-executed clinical trials, which are submitted by the sponsor to provide the needed demonstration of safety and efficacy.”
Holub also notes that the regulatory approval process, which can take between 130 and 300 days, is conducted separately for each submission and that it is “not easier or faster to obtain market authorization for use of Gardasil in males” simply because the vaccine was approved in women.
Even if the vaccine were approved in Canada, Palefsky says policy makers and parents would need to be convinced before Gardasil is provided free for school-aged boys.
“If you’re asking is there going to be a bigger hurdle to getting boys vaccinated routinely compared with girls, I think the answer is yes,” he says. “It won’t be easy to sell the vaccine on that basis to Johnny’s mom, especially since it’s unlikely Johnny will have come out at the time when he would most benefit from vaccination, which is prior to initiation of sexual activity.”