Two preventive HPV vaccines are on the market today; they protect healthy, often pre-sexually active girls and women from acquiring HPV infection. However, they are not effective against pre-existing HPV infections and have no therapeutic effect on neoplasia or cancer caused by HPV infection (Hildesheim et al., 2007; Hung et al., 2008).

Relying on the progressive coverage provided by regular vaccination of the younger generations is also unsatisfactory as it is estimated that it will take at least 30 years, from the implementation of mass vaccination with prophylactic vaccines and assuming 70% coverage, to reduce HSIL and cervical cancer caused by HPV16 and/or HPV18 by 50% (Garnett et al., 2006). Because mass vaccination is rarely achieved, it can therefore be assumed that it will actually take substantially longer to generate a broad immunity status in the general population.

This is of great concern since there are currently millions of sexually active women worldwide with progressive HPV disease at any given point of time (de Sanjose et al., 2007). Consequently, the availability of therapeutic vaccines for HPV affected women will constitute a way to accelerate the control of cervical cancer (Kanodia et al., 2008; Brinkman et al., 2007).