Progress on HPV Vaccine Offers Great Hope to Developing Countries
Data published earlier this month have created an opinion among many in the public health and research communities that we are on the brink of significantly eliminating the threat of cervical cancer. This would be a public health boon to many developing countries, which bear the brunt of the 230,000 annual deaths from this cancer.
According to the results of a phase II clinical trial published earlier this month in The Lancet involving more than 1,100 women, a human papillomavirus (HPV) vaccine was safe and effective at preventing viral infections, as well as the abnormalities in the cells often associated with them. The vaccine targets two HPV types, 16 and 18, which together cause about 70 percent of all cervical cancers. Although the women in the Lancet study were only followed for 27 months, the study provides evidence that immunization with this type of HPV vaccine can confer a high degree of protection against infection with specific types of HPV and could be a valuable tool in the battle against the primary cause of cervical cancer. Encouragingly, similar results with longer follow-up were reported a few weeks ago at an American Society of Microbiology meeting with an HPV vaccine that targets HPV type 16.
It was Drs. Mark Schiffman, Allan Hildesheim, and colleagues in the Division of Cancer Epidemiology and Genetics (DCEG) who made the initial discoveries that linked infection with HPV to the development of cervical cancer. And the companies producing these vaccines - GlaxoSmithKline (GSK) and Merck, respectively - did so based on technology developed by NCI scientists, led by Drs. John Schiller and Doug Lowy in NCI's Center for Cancer Research (CCR). Work by Drs. Lowy, Schiller, and CCR colleagues laid the foundation for a "virus-like particle" HPV vaccine and the subsequent development and testing of the vaccine in animal models and early stage human trials that set the stage for the promising results seen in these recent phase II trials. NCI involvement in HPV vaccine development has not abated. As reported recently in the NCI Cancer Bulletin, DCEG has initiated an 8-year, phase III study involving 12,000 to 15,000 women in Costa Rica to test GSK's HPV 16/18 vaccine. Costa Rica is just one of many developing countries that could benefit from an HPV vaccine. Cervical cancer rates there are alarmingly high, especially in coastal areas, where access to basic health care is extremely limited. Most developing countries do not have the infrastructure to operate cancer screening programs, lack the systems to ensure that women with a positive Pap smear get appropriate follow-up care, and must overcome cultural barriers that limit the effectiveness of available screening programs.
In addition to our efforts in HPV vaccine clinical trials, Drs. Schiller, Lowy, and colleagues are continuing their research in this area. Among other things, they have developed the first high-throughput assay that can allow researchers developing HPV vaccines to more efficiently and affordably perform tests to determine if the vaccines can induce an immune response against other oncogenic HPV types. They have made this assay available to other researchers, generating increased interest and potentially accelerating the production of vaccines that protect against multiple HPV types.
As was highlighted in the recent international issue of the Bulletin, NCI has a mandate to prevent and ease the suffering and death due to cancer worldwide. We have seen exciting advances in our international collaboration over the past decade and, with NCI leading the way in research to pursue new paths of cancer prevention and treatment, we are committed to translating these advances into a reduced global burden of cancer.
Dr. Andrew C. von Eschenbach