While a vaccine already exists to prevent human papillomavirus (HPV), the main cause of cervical cancer, more than 20 therapeutic HPV vaccine candidates are in development, said the WHO.
The world body has released a report to guide developers about the preferred product characteristics (PPCs) for any new therapeutic vaccines in priority disease areas – primarily low and middle-income countries (LMICs).
Eliminating cervical cancer, which kills one woman every 90 seconds, is a major public health initiative for WHO, reports Health Policy Watch. Goals of its current strategy are to vaccinate 90% of girls with preventive vaccines, screen 70% of women with high-performance tests like DNA screening, and treat 90% of women with cervical cancer or precancerous cells in the cervix by 2030.
Millions have missed out
A therapeutic vaccine “is likely to be especially beneficial for adult women who did not receive the HPV vaccination before contracting the virus and in poorer countries, where millions of women still lack access to effective cervical screening and cancer treatments”, said the agency.
Although the HPV preventive vaccine targets school children before they become sexually active – most countries offer it to boys too – only 28 of the 47 countries in the WHO African Region had introduced prophylactic HPV vaccine into their national immunisation programmes by January.
Nigeria introduced it in parts of the country last October, while others do not yet have it as part of their immunisation programme.
Complementary vaccines
An expert group convened by the WHO said therapeutic vaccines would be useful in places where it has been difficult to scale up cervical cancer screening and treatment, and as “an alternative, simpler treatment to reduce loss to follow-up” of women who are effectively treated after a positive test.
“A wide variety of approaches has been used to develop therapeutic HPV vaccine candidates, including peptide, protein, DNA, RNA, and bacterial- and viral-vectored vaccine platforms,” according to the WHO.
Vaccine candidates have mainly targeted the regression of CIN2/3 lesions and invasive cervical cancer, while a few focusing on clearance of high-risk HPV infection are now in phase 1 and 2 studies.
Vaccines in development include candidates from Barinthus Biotherapeutics, TheraVectys and Genticel.
Therapeutic HPV jabs would ideally have “high efficacy in both clearing high-risk HPV infection to prevent development of cervical pre-cancers, and treating high-grade pre-cancers that have already developed”, said the WHO.
At a minimum, first-generation vaccines would be expected to clear infection and/or prevent high-grade cervical pre-cancer due to HPV types 16 and 18.
These vaccines could be given to adult women through population-based vaccine delivery – without a diagnostic test if that were not available.
Therapeutic HPV vaccines that could reverse the progression of high-grade cervical pre-cancers (at a minimum HPV 16 and 18) could be used as an alternative or adjunct to existing cervical treatments in women with cervical pre-cancer, according to positive screening tests.
HPV guide
See more from MedicalBrief archives:
HPV one-dose jab campaign to now include private schools
Global meta-analysis finds one in five men possibly has cancerous HPV
HPV vaccine cuts cervical cancer by nearly 90% — UK population registry study
Single HPV vaccine dose may be effective against cervical cancer