The only HIV vaccine currently in Phase III human trials is considered a failure, and research has been halted. The experimental vaccine, which is being tested in thousands of participants in Europe, North and South America and Africa, has failed to shift the focus of current research to a few other candidates who are only in early human trials.
The trial, dubbed "Mosaico," began in 2019 as one of three promising late-stage real-world tests of several types of HIV vaccines that have been in development for more than a decade. Mosaico is the hope of the latter of the three major trials.
The first trial began in 2016 and recruited more than 5,000 people in South Africa. The trial, dubbed "Uhambo," is testing a vaccine regimen that combines two different experimental HIV vaccines. Early data analysis showed that Uhambo stopped in 2020 after a similar number of HIV infections were detected in both the vaccine and placebo groups.
The second trial, called "Imbokodo," began in 2017 and focused on about 2,500 women in sub-Saharan Africa. The study is testing a vaccine similar to the Mosaico trial, offering a variety of different HIV antigens in a single injection. Imbokodo was discontinued in mid-2021 after interim data analysis again found that the vaccine did not provide protection against HIV infection.
Now, in a new joint statement from the National Institutes of Health, Johnson & Johnson, and the HIV Vaccine Testing Network (HVRT), Mosaico has officially ceased production and development. Mosaico's story is sad. After recruiting about 3900 men at 50 trial sites, interim data analysis showed similar rates of HIV infection between the placebo and vaccine groups.
Susan Buchbinder from HVTN and co-chair of the Mosaico trial, expressed disappointment and hope in a statement about the study's failure.
"These results are disappointing for our research partners and others who have worked for decades to develop a vaccine to end the HIV/AIDS pandemic," Buchbinder said. While HIV continues to prove uniquely challenging for developing vaccines, the HIV research community remains fully committed to doing so, with each study bringing us one step closer to that goal.
Penny Heaton, a member of Johnson & Johnson's vaccine research team, also expressed disappointment with the results of years of work and investment. Heaton did say that this is not the end of the pharmaceutical company's investment in HIV treatment.
"We remain steadfast in our commitment to driving innovation in HIV, and we hope that Mosaico's data will shed light on future efforts to develop safe and effective vaccines," Heaton said. We thank our Mosaico partners as well as the study investigators, staff and participants." "
Mosaico's failure is another setback for HIV/AIDS research, which has faced decades of challenging clinical trial failures. Of course, there are several promising new HIV vaccine candidates at different stages of research – mRNA vaccines in particular have recently achieved exciting preclinical results, but these technologies are only now entering early human testing, and larger trials are still years away.
Larry Corey, another researcher who collaborated with HVT, remains optimistic about the progress being made. Corey said that every failed clinical trial brings new discoveries. Research is streamlining, and even without a successful vaccine, treatments for HIV are constantly improving.
"HIV is an ever-changing and challenging adversary. When our best efforts don't produce the results we expect, we become disappointed. However, we have come a long way since the time when life expectancy after being diagnosed with HIV was short, and many discoveries have been made. "
Transmission electron micrograph showing germination and replication of HIV-1 viral particles (red) from a portion of long-term infected H9 cells (blue). The granules are at different stages of maturation; Curved/semicircular is an immature particle that has begun to form but is still part of the cell. The immature particles slowly change morphology, turning into mature forms and exhibiting the typical "conical or spherical-shaped NIAID."