Researchers have found that an investigational HIV vaccine regimen was well-tolerated and generated immune responses against the deadly virus in healthy adults. The findings by APPROACH — an early-stage clinical trial — are based on “mosaic” technology that combines immune-stimulating proteins from four different HIV strains, representing different types of virus from around the globe.

The new vaccine regimen — called as “Ad26 mosaic” — were well-tolerated and capable of generating anti-HIV immune responses in healthy HIV-negative adults.

Importantly, Ad26 mosaic was found as most protective in pre-clinical studies in animals elicited among the greatest immune responses in the study participants.

“A safe and effective HIV vaccine would be a powerful tool to reduce new HIV infections worldwide and help bring about a durable end to the HIV/AIDS pandemic,” said Anthony S. Fauci, Director at the National Institute of Allergy and Infectious Diseases (NIAID) in Maryland.

“By exploring multiple promising avenues of vaccine development research, we expand our opportunities to achieve these goals,” Fauci added.

The results were presented at the ninth International AIDS Society Conference on HIV Science in Paris.

For the study, APPROACH involved nearly 400 volunteers in the US, Rwanda, Uganda, South Africa and Thailand who were randomly assigned to receive one of seven experimental vaccine regimens or a placebo.

The Ad26 mosaic vaccine delivers its four immunogens to human cells through an adenovirus (common cold virus) that is genetically engineered to cause infection but not illness.

The results showed that Ad26 is safe and triggered a strong immune response to the different HIV strains in the volunteers.

The promising, early-stage results from the APPROACH study support further evaluation of these candidate vaccines to assess their ability to protect those at risk of acquiring HIV, the researchers said.

The APPROACH findings, as well as results expected in late 2017 from another early-stage clinical trial called TRAVERSE, will form the basis of the decision whether to move forward with a larger trial in southern Africa to evaluate vaccine safety and efficacy among women at risk of acquiring HIV.