Vaccination and testing for HPV could eradicate CC

According to a cervical cancer (CC) screening expert, Professor Jack Cuzick, from Cancer Research UK, the disease could be eradicated within the next 50 years if countries implement national screening programmes based on the detection of the human papillomavirus (HPV). Cuzick told the recent joint 15th ECCO and 34th ESMO Congress that while the current HPV vaccines protect against two cancer-causing strains of the HPV virus, soon there would be vaccines available that protect against nine types. If vaccination were to be combined with HPV screening, which is much more sensitive than the currently used Pap smear test, then eventually the cancer would disappear in those countries that had successfully implemented national programmes. However, this would require political will and effort at both national and European levels.

The current vaccine holds the promise of eradicating approximately 70 to 75 per cent of CC (caused by HPV types 16 and 18), and there appears to be some additional cross protection amongst types that are closely related to 16 or 18, in particular 31, 45 and a part of 33. There are new vaccines being planned that will vaccinate against nine types; if they are successful, there should be no need to screen women that have been vaccinated at all.

The Pap test relies on subjective assessments by people examining the cells in the smear with a microscope and therefore is open to human error. Cuzick believes that such errors will increase as the proportions of smears with affected cells decline due to increasing numbers of women having been vaccinated. In contrast, the HPV test is almost completely automated, is designed to detect the virus in the smear rather than relying on visual examination and therefore is much less likely to be affected by human error. Cuzick commented: "there's overwhelming evidence that HPV screening is more effective than the Pap smear test, which misses about a third to a half of all high-grade lesions". However, Cuzick warned that the EU and national governments should take the initiative in discussions on implementing screening and vaccination programmes, rather than leaving it to pharmaceutical companies to lead the debate.

During the last fortnight, much data have been reported in relation to CC drug and vaccine trials. Of particular note, results from the PATRICIA (PApilloma TRIal Cervical cancer In young Adults or HPV 008) study showed that GlaxoSmithKline's Cervarix is highly effective at protecting against the two most common CC-causing HPV types, 16 and 18. Furthermore, Cervarix demonstrated efficacy against cervical intraepithelial neoplasia 2+ lesions associated with 12 additional HPV types beyond 16 and 18, including HPV 31, 33 and 45.

In addition, Phase I trial results of ADXS11-001 have shown 36-month survival in three of the 13 evaluable patients treated with Advaxis' therapeutic cancer vaccine, which treats women who have already developed CC as a result of HPV infection, indicating the possibility of persistent immune protection. Further, interim safety and immunogenicity data from a Phase I trial of Inovio Biomedical's VGX-3100 showed that the therapeutic CC vaccine was generally safe and well tolerated, plus it achieved significant cellular and humoral immune responses at the lowest dose administered. VGX-3100 is a DNA vaccine targeting the E6 and E7 proteins of HPV types 16 and 18.

Alice Rossiter - Cancer Drug News Editor