Gardasil May Have Some Competition

By: Grete Dudek, CIS Compliance Associate
gretedudek@cis-partners.com

A little over one year after Dana Zelig’s article “CDC and FDA Stand by Merck’s Gardasil” (1) was published on the Pharma Compliance Blog, the FDA and CDC released a statement saying that they “continue to find that Gardasil is a safe and effective vaccine.” (2) The timing of this report is interesting, because Gardasil, a Human Pappillomavirus (HPV) vaccine manufactured by Merck, and Cervarix, an HPV vaccine manufactured GlaxoSmithKline, are both going before the FDA Vaccines and Related Biological Products Advisory Committee on September 9th. (3) The Committee will be debating whether or not to expand the use of Gardasil, which is currently only recommended for females ages 9-26, to also include males. The thought is that if men are vaccinated as well, not only will they be protected from genital warts and certain cancers, they will also prevent the spread of HPV to girls and women. The second topic to be addressed by the Advisory Committee meeting is the approval of Cervarix. If Cervarix is approved, Gardasil will face competition from another HPV vaccine for the first time in U.S. markets; the drugs are currently both approved in other countries around the world.

Although the vaccines were both developed to protect against HPV, there are some notable differences between them. Gardasil is a tetravalent vaccine, meaning it contains and protects against 4 strains of HPV- two that cause 70% of cervical cancer, and two that cause 90% of genital warts. Cervarix protects against two strains, the same two most common cancer causing strains as Gardasil, but is designed with an adjuvant to promote long term anti-body production. Cervarix has also been shown to protect against the five most cervical cancer-causing strains of HPV (4), and GSK released information at the International Human Papillomavirus conference in Sweden that Cervarix “generated a significantly higher immune response (neutralising antibodies and B cells) compared to Gardasil (5)”. Gardasil, too, has been shown to protect against strains of HPV other than the four contained in the vaccine.

A second HPV vaccine entering the U.S. market might refuel the debate on whether young girls should be vaccinated. The CDC has recommended that girls as young as 11 or 12 get vaccinated, but when the states tried to make the vaccine mandatory for school entry, parents refused, saying that the vaccine could promote promiscuity. Although the vaccines are safe, there is concern that “even a rare thing may be too much of a risk (6),” especially for healthy young girls, and women who have regular Pap tests. Cervical cancer “particularly affects girls who don’t have access to health care and Pap tests, (6)” and “since 80 percent of the 280,000 cervical cancer deaths a year occur in poor countries (7),” these vaccines could be particularly valuable in developing countries. With limited access to healthcare, Pap tests or other regular cervical cancer screenings, women in developing countries are at risk for late detection of cervical cancer. The World Health Organization (WHO) has approved Gardasil and Cervarix for use in developing countries, allowing the UN and non-profit organizations to purchase and distribute the vaccines to those who need them most.

Sources:
1. http://pharmacomplianceblog.blogspot.com/2008/08/cdc-and-fda-stand-by-mercks-gardasil.html
2. http://www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/VaccineSafety/ucm179549.htm
3. http://www.fda.gov/AdvisoryCommittees/Calendar/ucm178920.htm
4. http://www.fiercepharma.com/story/glaxos-cervarix-wards-more-hpv-strains/2009-07-07
5. http://www.gsk.com/media/pressreleases/2009/2009_pressrelease_10051.htm
6. http://www.nytimes.com/2009/08/19/health/research/19vaccine.html?em
7. http://www.reuters.com/article/rbssHealthcareNews/idUSL948126520090709