By Wilson da Silva
SYDNEY – Clinical trials of a vaccine for cervical cancer could begin by the mid-1990s, Australian researchers said on Wednesday.
Dr Robert Tindle and Dr Ian Frazer of the University of Queensland said their research team had successfully halted cervical cancer in mice using an experimental vaccine developed over the past three years.
TD “We have induced immunity (against cervical cancer) in mice using an experimental vaccine,” Tindle said by telephone from Brisbane. “We hope to extrapolate the results to humans in the next couple of years.”
“The evidence is very reassuring (that it can be applied to humans),” said Tindle, an immunologist at the university’s laboratory in Brisbane’s Princess Alexandra Hospital.
Tindle said some studies suggest that small quantities of the virus which can cause cervical cancer, called the human papilloma virus or HPV, are present in 50 to 70 per cent of people but for some reason remain inactive in the body.
The virus commonly causes genital warts, but only six of the 60 known virus strains have been linked to cervical cancer. The cancerous strains all carry a protein, known as E-7, which is suspected of triggering the cancer.
The other 54 strains have not been linked to cervical cancer and mostly lie dormant in the body, often causing the warts.
In women who develop cervical cancer, the body’s immune system appears to ignore the E-7 protein, Tindle said. The body’s immune system even learns to tolerate the HPV, said Tindle, whose team is collaborating with groups in Germany and Britain.
“We’re probably ahead of the other groups, we know more about the E-7 protein than anyone else,” he said.
The researchers believe their vaccine makes the tell-tale E-7 protein more recognisable to the body’s immune system, which then destroys the virus.
But it will take years to understand what parts of the E-7 protein the human immune system recognises easily, and to learn how to safely trigger an immune response.
Once perfected, the vaccine could provide treatment for cervical cancer sufferers even late into an infection.
First trials, due to begin in three to five years, are likely to involve women who already have the cancer.
They will later be expanded to those who have returned abnormal pap smears indicating pre-cancerous activity. Pap smears are common gynaecological tests that many women in industrialised countries take annually.
Eventually the vaccine would be available to all women, Tindle said.
“Cervical cancer is a common treatable disease if it is detected early but pap smears are not even available in two-thirds of the world,” said Frazer, director of the laboratory.
He said cervical cancer is a leading killer of women in developing countries.
Obvious genital warts develop in five to 10 per cent of sexually active women, and one in 1,000 women infected is likely to develop cervical cancer if the condition remains untreated, Tindle said.
Frazer said the team’s research could also lead to the development of more effective pap smears.