Another HIV vaccine candidate fails in clinical trial

There is more hope on the horizon, experts say, despite J&J's setback.
A vaccine pharmacist prepares blind samples as part of an HIV vaccine trial on March 16, 2022 in Masaka, Uganda.

A vaccine pharmacist prepares blind samples as part of an HIV vaccine trial on March 16, 2022 in Masaka, Uganda. Luke Dray/Getty Images

The National Institute of Allergy and Infectious Diseases (NIAID) announced on January 18 that a Phase 3 clinical trial of a human immunodeficiency virus (HIV) vaccine in development from Johnson & Johnson (J&J) has failed. The vaccine proved to be ineffective at preventing infection.

Janssen, the vaccine division of J&J, began running this trial in 2019. It was stopped after a scheduled review, which revealed that there were roughly as many new HIV infections among people in the vaccine arm as in the placebo arm.

The trial, which is part of the Mosiaco study, had 3,900 volunteers across multiple countries, including Argentina, Brazil, Italy, Mexico, Peru, Poland, Puerto Rico, Spain, and the United States. The trial focused on cisgender and transgender people who have sex with men due partially to these populations’ vulnerability to the virus.

[Related: The first woman has been cured of HIV using donor stem cells.]

“We are disappointed with this outcome and stand in solidarity with the people and communities vulnerable to and affected by HIV,” said Penny Heaton, Janssen’s head of global therapeutics and vaccines, in a statement. “Though there have been significant advances in prevention since the beginning of the global epidemic, 1.5 million people acquired HIV in 2021 alone, underscoring the high unmet need for new options and why we have long worked to tackle this global health challenge. We remain steadfast in our commitment to advancing innovation in HIV, and we hope the data from Mosaico will provide insights for future efforts to develop a safe and effective vaccine. We are grateful to our Mosaico partners and the study investigators, staff and participants.”

This vaccine was given in four injections over one year and was based on “mosaic” immunogens, where the vaccine is built using components (or pieces) that feature elements of multiple HIV subtypes. The goal was for the vaccine to start an immune response to a broad range of HIV strains and used a common cold virus (adenovirus 26) to deliver antigens. This is the same the same antigen delivery system that J&J’s COVID-19 vaccine used. It was the only HIV vaccine in late-stage clinical trials.

In an interview with The New York Times, former NIAID director Anthony Fauci said that the news is “disappointing, but it isn’t the end of the effort toward developing a vaccine. There are other strategic approaches.”

Multiple HIV vaccine candidates have stalled over the past few decades. In 2021, Imbokodo trial (a Phase 2b trial of a similar vaccine candidate) stopped when data indicated that it was not preventing infections. The vaccine was being studied in women in sub-Saharan Africa.

According to some experts, this defeat sets progress towards a vaccine back by three to five years, but other options are in early-stage trials. In January 2022, Moderna began Phase I clinical trials for an HIV vaccine that uses the same mRNA technology as the pharmaceutical company’s COVID-19 vaccine.

Additionally, a small phase 1 clinical trial of another experimental two-dose HIV vaccine found that it could induce crucial broadly neutralizing antibody precursor B cells in 97 percent of study participants without significant side effects. These results were published in the journal Science in December 2022. “At the most general level, the trial results show that one can design vaccines that induce antibodies with pre-specified genetic features, and this may herald a new era of precision vaccines,” said William Schief, study co-author and researcher at The Scripps Research Institute, in a December press release.

[Related: The first people have received an experimental mRNA HIV vaccine.]

HIV is no longer a death sentence in wealthy countries due to medications that reduce viral load, or the amount of the virus in the blood. There are currently pills and bimonthly injections that can prevent infection in HIV negative individuals. However, these medications can be inaccessible to the people who need it most, and HIV treatment must be taken for the rest of a patient’s life after diagnosis.

HIV still infects about 1.5 million people each year and kills roughly 650,000. The virus attacks the body’s immune system and destroys white blood cells, weakening immunity against other opportunistic infections.

“The ultimate prevention modality for any infection, particularly viral infection, is a vaccine that’s safe and effective,” Fauci said. “That’s the reason why the field is going to continue to pursue very active research in that area.”

According to the Centers for Disease Control and Prevention (CDC), some of the best ways to prevent HIV infection using wearing condoms during sexual intercourse, not sharing needles, and continually testing for sexually transmitted disease and infections.