Research on Cervical Cancer Vaccines

National Cancer Institute
Monday, 12 April 1999

When people become sexually active, many are exposed for the first time to the human papillomavirus (HPV). Scientists have found that exposure to the virus has significant health implications, particularly for women, because after HPV enters the body, some strains — including HPV-16 and HPV-18 — can, over time, trigger cancers of the cervix. In fact, researchers now believe HPV causes more than 90 percent of cervical cancer in the United States and throughout the world.

These discoveries have raised the possibility that cervical cancer might be prevented with vaccines. Much like a childhood booster shot, youngsters who are innoculated early in life with an inactive, non-infecting particle of HPV might be able to train their immune systems to recognize the virus and later destroy active HPV when they are exposed to it.

In recent years, work on HPV vaccines has progressed rapidly. Some of this progress stems from the development of recombinant DNA techniques that mass produce virus-like particles, that mirror the chemical structure of proteins found on the outer coat of HPV, the part of the virus that immune cells encounter and attack. Each particle then can be tested in the laboratory for its ability to induce an immune response, an indication of whether or not a particle is a viable candidate as a vaccine.

Researchers also are testing other types of vaccines, including a fusion protein, which combines one of the coat proteins with a portion of an HPV protein that is not normally in the virus particle. Also under development are "naked DNA" vaccines, created by combining one or more genes that encode HPV surface proteins with plasmid DNA.

Currently, at least six vaccines are under development worldwide. Below are capsule description of work now under way in the United States or involving American companies:

- National Cancer Institute is testing a virus-like particle from HPV16 in a phase I/II study in people at The Johns Hopkins University, Baltimore. Preliminary results indicate that a low-dose injection of the vaccine induces high levels of protective antibodies against HPV.

- MedImmune, Inc., Gaithersburg, Md., recently completed a phase I vaccine study in people, which was conducted at the University of Rochester in New York. The study, which used a virus-like particle from the outer coat of HPV11, showed that the candidate vaccine produced high levels of antibodies against the virus. The company also has cervical cancer candidate vaccines under development in collaboration with SmithKline Beecham, Philadelphia.

- Apollon Inc., Malvern, Pa., is developing naked DNA HPV vaccines.

- Merck Pharmaceuticals, West Point, Pa., has a collaborative clinical research program on HPV vaccines with the University of Queensland, Australia, and others.

For more information, or to contact National Cancer Institute, see their website at: www.cancer.gov