New Imbokodo findings show a 4-dose regimen was only about 25% effective in preventing HIV in at-risk women, hindering progress for the vaccine.
The proof-of-concept HIV vaccine Imbokodo study did not meet its pre-defined criteria for efficacy that would warrant continued follow-up assessment, according to an announcement from Johnson & Johnson that would hinder progress toward a potential HIV prophylaxis.
The Imbokodo study, which compared 4 doses of an adenovirus 26-based mosaic vaccine regimen administered over 12 months versus placebo in 2637 cisgender women from 5 sub-Saharan African countries, found the investigational vaccine was just 25.2% effective in preventing HIV in the at-risk population (95% CI, -10.5 to 49.3). Though the regimen was deemed safe by adverse event profiles, the investigators noted a significant rate of HIV infection among vaccinated participants.
Nonetheless, the phase 3 Johnson & Johnson companion Mosaico trial—which is observing a similar vaccine regimen and a protein boost in 3800 men and transgender people from 8 countries in the Americas and Europe—will proceed.
In a statement regarding the Imbokodo trial shortcomings, AIDS Vaccine Advocacy Coalition (AVAC) Executive Director Mitchell Warren expressed measured regret in the continued challenge of HIV vaccination research.
“It is very disappointing that this particular vaccine candidate did not work in this trial, but the trial was well-conducted and got an answer quickly,” Mitchell said. “HIV remains a global threat, and a safe, efficacious and accessible HIV vaccine is still needed to contribute towards curbing new infections and providing a durable end to the pandemic.”
Warren shared hope for more positive outcomes in the Mosaico and PrEPVacc studies—the latter being an African-based combined assessment of investigative HIV vaccines and pre-exposure prophylaxis (PrEP) options in at-risk persons. The trial sought at least 1668 participants aged 18-40 years, and is anticipated to run from 2018-2023.
That said, Warren stressed the need for “diversity and creativity” in pursuing the next HIV vaccine candidates.
“The field must focus on new hypotheses driven by this result and the recent antibody-mediated prevention study results, both of which showed some trends towards efficacy,” Warren said.
In a recent interview with Contagion®, David Koren, PharmD, MPH, BCPS, a Clinical Pharmacist Specialist in ID/HIV at Temple University Hospital, emphasized the need for cross-care collaboration in the pursuit of HIV eradication through products including available PrEP and would-be vaccine options.
“We know that these medications work and are efficacious to do what they’re set out to do,” Koren said. “But we’re not getting them into the hands of the people that need it.”