An experimental HIV vaccine appears to have passed its first test in humans. In a newly released study, the vaccine candidate produced the sort of immune response that scientists had been hoping for in 97% of recipients. Importantly, the vaccine also seemed to be safe and well-tolerated.
The vaccine candidate is known as eOD-GT8 60mer and was developed by researchers from the Scripps Research Institute. The Phase I trial testing eOD-GT8 60mer, first announced in 2018, was sponsored by the International AIDS Vaccine Initiative (IAVI). It’s part of a large collaboration between scientists at Scripps, the National Institutes of Health, the Fred Hutchinson Cancer Center, and other groups in the U.S. and Sweden. It involved 48 healthy participants, 36 of whom were given two doses of the vaccine eight weeks apart (these participants were divided into a low- and high-dose group).
HIV infection can be now effectively managed through lifelong antiviral therapy. But the virus has the ability to craftily change its structure once inside the body, making it hard for the immune system to recognize it for long. This means that sustained immunity to the virus, at least in most cases, has remained out of reach. But we’ve known for decades that some people can produce broadly neutralizing antibodies to the virus that can keep up with it. And scientists have been chasing after the elusive HIV vaccine capable of creating these antibodies ever since.
A new method for obtaining these antibodies, known as the germline-targeting strategy, is represented by eOD-GT8 60mer. In simple terms, the first dose of vaccine tries to prime a rare and select group of B cells into a state where they could produce these antibodies. Subsequent boosters are then supposed to reactivate these cells, eventually leading to durable and broadly neutralizing antibodies against HIV. And in the findings of this new trial, published Friday in Science, the first part of this strategy appears to be working.
The researchers found that 35 out of 36 volunteers appeared to generate the precursors to these broadly neutralizing antibodies and that this immune response only grew in strength following the second dose.
“The hope is that if you can induce this kind of immunity in people, you can protect them from some of these viruses that we’ve had a very hard time designing vaccines for that are effective,” Timothy Schacker, the program director in HIV medicine at the University of Minnesota Medical School, who was not involved in the research, told CNN. “So this is an important step forward.”
Phase I trials are primarily designed to test the safety of an experimental treatment. And the vaccine also did have a favorable safety profile, the researchers wrote, with no severe vaccine-related adverse reactions reported. The findings are timely as well, given that yesterday was World AIDS Day.
This study is only a proof of concept, though, the authors note. It will take more research in humans to confirm the early findings seen here, and to show that broadly neutralizing antibodies can be reliably coaxed through boosters. Any truly effective vaccine would also likely have to create a broad T cell response to HIV since T cells are often a crucial aspect of our immunity to germs. But if this research does continue to pan out, then scientists may one day be able to create vaccines that not only provide lasting protection against HIV, but other evasive diseases like hepatitis C, flu, and covid-19.
Another Phase I trial of eOD-GT8 60mer is already ongoing, and other similar vaccine candidates are being tested out in early human trials as well.