By Spy Uganda
The pharmaceutical company Johnson & Johnson has ended a phase 3 trial for an HIV vaccine after it proved ineffective.
The company said that the Mosaico study (also known as HPX3002/HVTN706) was not effective at stopping the transmission of HIV, although there were no safety issues with the vaccine.
“We are disappointed with this outcome and stand in solidarity with the people and communities vulnerable to and affected by HIV,” said Dr. Penny Heaton, Global Therapeutic Area Head, Vaccines, Janssen Research & Development.
“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.”
Despite the setback, there are multiple other HIV vaccine candidates being tested globally.
The news about the Johnson & Johnson vaccine comes weeks after a phase 1 study of a different experimental HIV vaccine showed promise.
The findings published December 2022 found that when a two-dose regimen of the vaccine is administered eight weeks apart, an immune response is triggered that may fight against HIV.
However, experts caution that it is early days in the testing process, since it is in the Phase 1 trial.
The vaccine, called eOD-GT8 60mer, was found to induce what are known as broadly neutralizing antibody precursors in the small group of volunteers. Broadly neutralizing antibodies is an approach that targets the core part of the virus, which remains unchanged even when a virus mutates. Among the participants, the vaccine induced the broadly neutralizing antibody precursor in 97% of the recipients.
“This is a case of a long journey beginning with first steps. We know that we do not have an effective vaccine against HIV and several previous attempts to create a vaccine have not been very successful,” said Dr. William Schaffner, professor of preventive medicine and health policy, and professor in the Division of Infectious Diseases at Vanderbilt University School of Medicine.
Previous vaccine candidates have failed in part because the virus mutates so rapidly.
“The current strategy and idea is because HIV mutates so much, on an hourly basis, it’s been very difficult to create an effective vaccine. Broadly neutralizing antibodies is the approach that gets to the core part of the virus, which is the part of the virus that doesn’t change,” said Dr. Jeffrey Klausner, clinical professor of population and public health sciences at the University of Southern California Keck School of Medicine. “This part of the virus is independent of these mutations.”
The start of the Phase 1 clinical trial began in 2018 and was designed to evaluate the safety of the experimental vaccine. During this phase, 48 adult volunteers were enrolled at George Washington University in Washington, D.C. and Fred Hutchinson Cancer Research Center in Seattle.
Eighteen of the participants received a 20-microgram dose of the vaccine and then a second dose eight weeks later. Another 18 of the participants received a 100-microgram dose and then the same eight weeks later. Finally, 12 participants received two doses of a saline placebo.
Following the first dose, the research found the recipients of the experimental vaccine had produced antibodies that could help protect against HIV infection. These antibodies then increased after the second dose.
The results are promising, but experts are remaining cautiously optimistic. The next step will be a Phase II investigation, which is like a Phase I study, only larger. Following a potentially successful Phase II study, then research would move to Phase III, which will determine whether or not the vaccine actually provides protection against the acquisition of HIV infection.
“We are not there yet by any means. We have a lot of stories and hope from vaccines in the past,” said Klausner. “Most of us in the field are cautiously optimistic. It’s promising, but it’s early days.”