Investigators Advance PrEPVacc Trial To Evaluate HIV Vaccine Efficacy

Investigators are moving into the post-recruitment phase of the PrEPVacc trial—a non-licensed study based in Africa that will provide insights on 2 investigational combination HIV vaccine regimens and a novel oral pre-exposure prophylaxis (PrEP) to prevent HIV vaccine—according to a recent press release.

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In March 2023, the trial finished enrolling participants from countries in East and South Africa, which include Masaka, Uganda; Mbeya, Tanzania; Dar es Salaam, Tanzania; and Durban, South Africa, who volunteered to participate in the study assessing possible treatment combinations to prevent HIV in this part of the world.

“Congratulations to all the PrEPVacc teams on reaching their enrolment targets for the trial. They have worked hard and skillfully through very challenging periods during the COVID-19 pandemic in order to successfully and safely reach this point,” said PrEPVacc trial director Eugene Ruzagira, in the press release.

Currently, PrEPVacc is the only HIV vaccine efficacy trial to be conducted anywhere in the world. It is also the first HIV vaccine efficacy trial to be conducted in East African countries. The PrEPVacc trial will compare 2 HIV vaccines against saline placebo:

• A vaccine regimen that combines a DNA- and protein-based vaccine.
• A vaccine regimen that combines DNA, modified Vaccinia virus Ankara (MVA), and a protein-based vaccine.

In addition, PrEPVacc will compare the efficacy of emtricitabine-tenofovir alafen (Descovy; Gilead) to standard of care emtricitabine-tenofovir disoproxil fumarate (Truvada; Gilead). They are aiming to identify how oral PrEP can be best combined with a vaccine to prevent HIV.

Prior to PrEPVacc, investigators conducted a preliminary preparedness study titled Registration Cohort. During the preparedness study, local people joined a community advisory board or community working group and, on behalf of study participants and the community, raised concerns about rates of HIV infection and PrEP roll-out to investigators.

Following Registration Cohort, investigators screened 2215 healthy adults aged 10 to 40 years for enrollment in the PrEPVacc study. Investigators eventually enrolled 1512 participants, among whom 1504 started vaccinations in what will be a 4-dose series, 623 are still receiving vaccines, and 671 completed all vaccinations in the series.

During the 2 weeks following dose 3, participants will be given emtricitabine-tenofovir alafen or emtricitabine-tenofovir disoproxil fumarate. Participants will continue to take a form of PrEP that is equivalent to emtricitabine-tenofovir disoproxil fumarate thereafter, and investigators will evaluate efficacy and PrEP adherence patterns.

PrEPVacc is not a licensure trial, rather it is being conducted to evaluate vaccine safety and efficacy, which, if positive, may warrant the need for further clinical trials. The study is being led by the Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit.

“We have already shared outcomes of our social science work with relevant stakeholders and we are committed to sharing news about all results that emerge from PrEPVacc with the study participants and their communities first,” Ruzagira said in the press release. “The study is scheduled to disseminate its findings by December 2024.”

Reference

Business Announcement. African-led PrEPVacc HIV prevention study completes its enrolment. News Release. June 9, 2023. Accessed on June 12, 2023. https://www.eurekalert.org/news-releases/992032