Vaccines that can treat HPV could help save hundreds of thousands of lives lost to cervical cancer

While a highly effective vaccine exists to protect against human papillomavirus (HPV), which causes cervical cancer, millions of women in low- and middle-income countries - which account for the majority of cervical cancer cases - are still at risk. HPV vaccines only started to be rolled out in Africa a decade ago, so many won't have had access to the vaccine in time, nor do they have much access to screening and treatment.

For these women, 'therapeutic' vaccines against HPV - i.e. a vaccine given after an HPV infection rather than before - could be lifesaving.

Yesterday, the World Health Organization (WHO) issued a report on the preferred characteristics of these therapeutic HPV vaccines - including which populations a vaccine should be useful for, safety and efficacy, and immunisation strategies - as a way of guiding researchers and manufacturers.

"Therapeutic HPV vaccines could be a catalytic innovation [...] increasing options for the millions of women who have already acquired HPV and reducing their risks of developing life-threatening cancer in the future"

- Dr Sami Gottlieb, a medical doctor and epidemiologist within WHO's Department of Sexual and Reproductive Health and Research

Stopping cervical cancer

Cervical cancer is one of the leading killers of women. It claims the life of one woman every two minutes - in 2020, cervical cancer killed 342,000 women, 90% of whom lived in low- and middle-income countries.

HPV is one of the most common STIs globally and by the age of 45, around four in five men and women will have had at least one HPV infection. In 90% of people, the body will clear the virus; in some people, however, HPV can cause cancers including cervical cancer.

The HPV vaccine prevents about 98% of HPV infections, which means it is critical to stopping cervical cancer. It is given to young girls between the ages of 9 and 14 years to prime their immune systems before they have any sexual contact.

However, as the HPV vaccine is still relatively new and only now beginning to reach lower-income countries in large numbers, millions of women are not protected against the virus, and the cervical cancer that can result.

Therapeutic vaccines

Vaccines are typically used as prophylactics to prime our immune systems in case we encounter pathogens that cause deadly diseases. However, advances in immunotherapy are ushering in a new wave of therapeutic vaccines that are used after an infection, to stimulate our immune systems to fight hard against a pathogen that is already in our bodies.

The first therapeutic vaccine to be approved by the US Food and Drug Administration (FDA) was in 2010 for Provenge, used to treat men with advanced prostate cancer. Since then, other therapeutic vaccines have been in development against HIV and HPV.

There are currently over 20 therapeutic HPV vaccine candidates at different stages of development, with several in clinical trials. The goal of these therapeutic vaccines is to destroy cells that have already been infected with the virus and begun to transform into precancerous or cancerous cells.

In high-income countries, where screening for changes in cervical cells is more routine than in lower-income ones, precancerous or cancerous cells can be detected by screening and biopsy and treated through surgery. However, many women in lower-income countries have no access to either screening or surgery: a therapeutic vaccine could make a huge difference.

Complementing existing approaches

The WHO is targeting the elimination of cervical cancer worldwide and sees therapeutic vaccines as complementary to existing approaches.
"To eliminate cervical cancer, it will be essential to expand access to existing interventions now - lifesaving preventive vaccinations, timely screenings, and effective treatment - all are critical for success," said Dr Sami Gottlieb, a medical doctor and epidemiologist within WHO's Department of Sexual and Reproductive Health and Research.

"Therapeutic HPV vaccines could be a catalytic innovation to complement these efforts, increasing options for the millions of women who have already acquired HPV and reducing their risks of developing life-threatening cancer in the future."

The WHO report calls on vaccine makers to ensure the products are designed to be effective in low- and middle-income countries, where more than 90% of cervical cancer-related deaths occur.

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