JJ's HIV vaccine trial discontinued due to ineffectiveness

The virus' ability to mutate rapidly prevents it from being identified by the host's immune system. Further, during an infection, the virus infects the T-lymphocytes, the very cells tasked to fight an infection, turning it into a reservoir from which new waves of infection can be easily launched.

The Mosaico Study

The investigational vaccine candidate developed by Janssen consisted of a mosaic of different subtypes of HIV presented to the immune system through a vector called adenovirus serotype 26 (Ad26.Mos4.HIV). The different subtypes were delivered through four vaccination visits in one year.

A mix of soluble gp140 proteins, a component of the viral envelope that plays a crucial role in the virus interacting with the host cells, was also administered during visits three and four. These proteins were administered along with aluminum phosphate, which serves as an adjuvant to increase the immune response against the infection.

The trial began in 2019 and included 3,900 cisgender men (men who have always identified as male) and transgender individuals who have sex with cisgender men and transgender individuals at over 50 sites in Europe, South America, and the U.S.

Failure of the trial

The vaccinations were completed in October 2022. Data available from the trial was reviewed by the Data and Safety Monitoring Board (DSMB) to find that the trial did not meet its primary endpoint of protecting individuals against HIV infection. Therefore, the company has decided to discontinue the trials and notify the participants.

The findings were not completely surprising since the Phase 2b trial of the vaccine carried out in sub-Saharan African countries in cisgender women also showed that the vaccine was ineffective. That trial was halted in 2021, the press release added. The study investigators ensured that individuals who contracted HIV during the trial received prompt treatment and care.

The DSMB did not identify any safety issues with the vaccine regimen showing that the technology could still be deployed for developing vaccines against other diseases or for HIV as well.

"We are disappointed with this outcome and stand in solidarity with the people and communities vulnerable to and affected by HIV," said Penny Heaton, M.D., Global Therapeutic Area Head, Vaccines at Janssen Research & Development. "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."

There are many treatment options that are now available to treat HIV infection, even though a cure is still not available. In the U.S., oral pills and shots have been approved that help in the prevention of the infection. Since these options remain inaccessible to people who need them the most, a vaccine is a preferable way of preventing the virus from spreading.

In 2021 alone, 1.5 million people have been estimated to have acquired the virus. Moderna began a Phase I trial for its mRNA vaccine candidate in May last year.