PRISMA AND EXTEND 2.0 FOLLOW-UP OF STUDY PARTICIPANTS

Human papillomavirus (HPV) infection is necessary for the development of cervical cancer. Worldwide, infection with HPV types 16 and 18 account for approximately 70% of cervical cancer cases. Cervical cancer could be nearly eliminated as a public health problem if prophylactic HPV vaccination and cervical cancer screening with effective diagnostic follow up and treatment of cervical precancers were deployed globally.

Yet, less than 10% of young girls receive HPV vaccination and similarly low proportion of women receive cervical cancer screening globally. Consequently, cervical cancer burden is expected to increase over the coming century despite the 2018 WHO call for cervical cancer elimination as a public health problem. NCI continues to push forward cervical cancer prevention research on both HPV vaccination and screening.

PRISMA

PRISMA is a randomized, controlled clinical trial of 5000 women aged 18-30-years to quantitate the reduction in incident cervical HPV16/18 persistent infections afforded by a single dose of the bivalent and nonavalent HPV vaccines compared to no vaccination, the default standard in the majority of the world for women over the age of 14-years.

In FY23, the window for the first 12-month follow-up visit opened, study forms and manuals were updated, and staff were trained in the follow-up procedures. EXTEND2.0:

The Costa Rica HPV Vaccine Trial (CVT) was a community-based, pre-licensure, randomized clinical trial, to evaluate the VLP-based, bivalent HPV vaccine. One of the more unexpected and novel discoveries showed that, in a post-hoc analysis, protection over four years against HPV16/18 infections among women initially uninfected with these types was uniformly high for recipients of one, two, or three doses after four years of follow-up in the blinded phase of the CVT.

Among women who received a single dose, HPV16 and HPV18 antibody titers (assessed by ELISA) were substantially higher than those among unvaccinated women previously exposed to HPV16/18; titers remained stably elevated from 6-to-48 months post-vaccination, albeit at lower levels than for two or three doses. We initially extended CVT to 7 and 9-years; and further extended the effort for two additional visits from 991 women at years 14 and 16 (EXTEND).

The current study, EXTEND2.0, is for two more visits from 693 women at years 18 and 20. We aim to describe, by dose, the long-term positivity and stability of the antibody response to HPV vaccination.

In FY23, the window for the 18-year follow-up visit opened. Nearly 60% of the eligible women attended the visit with high compliance with blood collection (100%).