WASHINGTON, Dec. 16 (UPI) -- An experimental vaccine now before the Food and Drug Administration for review appears to be 100-percent effective in preventing vaginal cancer, vulvar cancer and genital warts in women who get vaccinated on schedule, researchers said Friday.
In fact, even in women who fail to comply with the three-dose vaccination schedule against human papilloma virus there is a 95-percent reduction in the risk of developing the precancerous changes.
"I'm very excited about these results because of the science involved and because of what it means to women," Diane Harper, associate professor of medicine at the Dartmouth Medical School in Lebanon, N.H., told United Press International.
Friday's announcement at the Interscience Conference on Antimicrobial Agents and Chemotherapy, sponsored by the American Society for microbiology in Washington, comes on the heels of a report two months ago showing that the vaccine, Gardasil, being developed by Merck & Co., was 100-percent effective in preventing cervical cancer.
The vaccine is targeted against four major strains of human papilloma virus. Two of the strains cause 70 percent of cervical, vaginal and other cancers; the other two strains are responsible for 90 percent of genital warts. There are more than 100 strains of human papilloma virus, a sexually transmitted disease. About 500,000 cases of cervical cancer worldwide are diagnosed each year, and 290,000 women die of the disease worldwide every year.
In the study Harper reported Friday, 2,261 women were vaccinated according to the protocol, receiving one initial inoculation and then a shot at one month and another at six months. After 18 months, none of those women developed genital warts or neoplasias -- precursors of vaginal or vulvar cancer.
On the other hand, 40 cases of genital warts or those dangerous neoplasias occurred among the 2,279 women who were administered sham injections on the same schedule.
"That means the vaccine was 100 percent effective," Harper said.
When looking at the "real-world" results, which included women who failed to get their inoculations on time or who did not get all three inoculations, 2,620 women received some active vaccine. and of that group three women were diagnosed with genital-tissue changes.
There were 2,628 women on the placebo schedule who received at least one inoculation. There were 59 of the lesions seen among these women.
"That means that even women who did not fulfill the inoculation schedule as they were supposed to still achieved 95 percent protection," Harper said.
"All the data we have seen on this vaccine looks wonderful," said Paul Offit, chief of the division of infectious diseases at the Children's Hospital of Philadelphia. "Occasionally we do see things that are phenomenally successful."
Offit told UPI that the vaccine appears to prevent the early changes that are linked to development of cervical and other genital cancers. It usually takes decades for those changes to become invasive cancer.
Harper noted that the vaccine is designed to protect women from being infected with human papilloma virus, and the women in the study were tested before entering the trial to make sure they were free of infection. The vaccine has yet to be tested to determine if it can prevent clinical changes from occurring in women already infected. Researchers also do not know how long the vaccine will protect individuals from infection.
Carlos Sattler, director of clinical research for Merck, the sponsor of the study, told UPI ongoing trials include seeing if the vaccine can prevent infection in men, and to see if the vaccine will protect boys and girls aged 9 to 15 from infection.
In the trial Harper reported, the subjects were sexually active women between the ages of 16 and 23.
