Research into what has been described as the last chance to develop an AIDS vaccine within this decade has been terminated, researchers announced at a conference in Harare, Zimbabwe, on Wednesday.
The trial, called Prepvacc, is testing two different vaccine regimens in about 1,500 volunteers in East and Southern Africa. After several other high-profile trials failed, a researcher at Prepvacc described the study this summer as a vaccine against AIDS until the 2030s"Last stand"。
Speaking at an international conference on HIV and sexually transmitted infections in Africa, the researchers said the study had been terminated early after an independent data monitoring committee concluded that it was nearly impossible to demonstrate efficacy.
Despite the disappointment, many AIDS vaccine researchers may not be surprised by the news. Prepvacc is considered a groundbreaking study, both as one of the first large African-led trials of an AIDS vaccine and one of the first to incorporate Prep.
But the trial used some older vaccine designs that some scientists doubt will provide adequate protection.
Pontiano Kaleebus, a researcher at Prepvacc, said in a statement:"As a result of this failure, now'Nowhere in the world is the efficacy of HIV vaccines being tested'。
Current efforts are limited to early, small-scale trials aimed at testing new technologies to give a chance at fighting the most sinister virus humanity has ever encountered. Caleb said it must now"More urgency"to advance these technologies.
He said:"We have come so far on the road to preventing AIDS, but we must look forward to a new generation of vaccine approaches and technologies to lead us forward once again. "We must also look forward to a new generation of leaders. We set up Prepvacc to increase our capacity in Africa so that we can conduct future trials ourselves and develop those who will lead trials in Africa.
The new strategy includes the adoption of HIV"Wanted"Encoded into another, more benign chronic virus, HIV is sent to specific immune cells"Wanted"。More popular is a species called"Phylogenetic mapping"(germline targeting), in which researchers use a series of different injections to induce the immune system to produce perfect, energy"Extermination"Antibodies to HIV.
Moderna, the National Institutes of Health, and i**i (formerly the International AIDS Vaccine Initiative) have all invested in the latter.
Mark Feinberg, CEO of the International AIDS Vaccine Initiative, said in an emailed statement:"Despite these results, the International AIDS Vaccine Initiative remains optimistic about the development of an AIDS vaccine. We believe that new methods aimed at inducing broadly neutralizing antibodies to HIV are the most promising way forward. "
Eugene Ruzagira, the head of the trial, said he hopes the Prepvacc data will eventually inform new work. While no new volunteers will be given any more medications, the researchers remain blinded to who is using which regimen and will continue to follow participants into next year. After that, they will look at blood samples and data to try to decipher exactly what went wrong.
Ruzajira said"The option of giving up a job is out of the question. The work needs to continue"。
However, some researchers are skeptical that the new technology can lead to a vaccine for HIV. Although the AIDS vaccine field has been struggling for 40 years, some companies have developed other ways to stop transmission in the long term: Prep injections every few months can virtually eliminate the risk of infection. Products are currently being developed for semi-annual injections and once-a-year injections.
Long-acting prep may raise the bar for the effectiveness of HIV vaccines, while also making vaccine trials more difficult. For example, researchers may no longer be able to compare a new vaccine to a placebo.
Prepvacc was an early attempt to conduct vaccine trials while providing patients with different forms of oral Prep. A partial study comparing two oral prep will continue.
Longtime vaccine researchers say that if one of the early-stage programs proves promising, the next vaccine study may require more out-of-the-box trial designs.