RIO Trial Demonstrates Long-Acting Immune-Based Therapy can achieve Sustained HIV Control
We are delighted to report promising results of the primary outcome of our RIO Trial, which tested long-acting immune-based therapies for HIV. The study recruited 68 participants across 12 clinical sites in the UK and Denmark, who stopped their antiretroviral treatment and received either a placebo or broadly neutralising antibodies (bNAbs). The results, presented at the Conference on Retroviruses and Opportunistic Infections (CROI) in San Francisco, USA, on 10th March 2025, showed that 75% of participants who received bNAbs were able to control the virus for 20 weeks, compared to 11% who received a placebo over the same timeframe.
This study is the first to show sustained viral control using these immune-based therapies, marking a significant step in HIV treatment research. The bNAbs not only targeted HIV directly but also stimulated the immune system, with some participants achieving undetectable levels of HIV in their reservoirs, which are cells that harbour latent infections.
While these results are still preliminary, they suggest bNAb therapies could offer a new path to managing HIV and possibly lead to a cure.
The study is still ongoing, with follow-up of the participants still part of the protocol continuing until 2027. Final results of all remaining protocol defined endpoints are anticipated towards the end of 2027, while a new arm of the study called Arm C will also be opening to recruit new participants in the coming weeks.
You can access the Imperial College London (Trial Sponsor) press release of the trial results here.
Professor Sarah Fidler was also invited to present the RIO Trial at the official CROI press conference, on 10th March 2025. Professor Fidler gave a short summary of the trial and how it demonstrated for the first time that long-acting immune-based therapy has shown sustained viral control in multiple participants. The session included a Q&A segment, where she was asked about how the RIO Trial compares to another HIV bNAb trial presented at CROI, and the potential for wider public implementation of long-acting immune-based therapy.
Time stamps of where you can watch about the RIO Trial:
Professor Fidler presents (3:05 – 6:22)
Press questions (16:04 – 20:10)
The RIO Trial was funded by the Gates Foundation, the National Institutes of Health (NIH) USA, the National Health Service (NHS) UK, and the Stavros Niarchos Foundation.
This research was also supported by funding from the National Institute for Health and Care Research (NIHR) Imperial Biomedical Research Centre (BRC), a translational research partnership between Imperial College London and Imperial College Healthcare NHS Trust, which also supports Imperial Clinical Trials Unit (ICTU) and Imperial Clinical Research Facility (ICRF).
The study team is deeply grateful to the trial funders, NHS partners in the UK and Denmark, community partners, laboratory and management teams, and Sponsor, without all of whom this research would not have been possible.
