For people living with HIV

What is the aim of the RIO study?

The RIO study is looking at whether a new type of treatment can keep viral load undetectable without antiretroviral treatment (ART). This will involve asking all participants to stop ART for a short time. 

The study will measure how long viral load stays undetectable without ART. It will also look at what happens to the HIV virus and immune system in blood samples. When virus becomes detectable in a blood test (viral rebound) you will be asked to re-start your ART.

RIO is funded by the Bill & Melinda Gates Foundation. Imperial College London is the trial Sponsor and the trial is coordinated by Imperial College London, The University of Oxford and The Rockefeller University.

Which treatments are being used? 

The treatment involves using two bNAbs (pronounced bee-nabs). 

bNAb stands for broadly neutralising monoclonal antibody. 

Antibodies are natural proteins produced by the body to fight infections. The bNAbs in the RIO trial are immune-based treatments that are being studied both to treat HIV and to prevent HIV infection. 

The two bNAbs in the RIO study are called 3BNC117LS and 10‑1074‑LS. Both are long-acting formulations – which is why only one dose is needed in the study. 

They will be given once in two separate infusions. An infusion is when medicines are delivered through a needle into a vein. Each infusion will take about 30 minutes but this visit might take up to a whole day.

bNAb infusion into a vein in the arm

How many people will take part? 

The study will enrol 72 people from several HIV centres in the UK and one HIV centre in Denmark. 

Where will the study take place? 

Regular monitoring visits will take place at your normal HIV clinic. 

The infusions take place at Hammersmith Hospital in London for the UK participants. This is part of the Imperial College Healthcare NHS Trust.

For Danish participants, the infusions will take place at the Aarhus University Hospital in Aarhus.

The study will pay for your time and travel costs for these visits.

What is involved in the study? 

The study will randomise 72 people to one of two groups.

This means that you cannot chose which group you join. This will be decided by chance by a computer. You will have an equal chance of being in either group. 

The study will then compare the results in each group, group A and B. 

The first part of the RIO study is ‘double blind’. This means that neither you, nor your doctor or nurse will know which group you are in. 

After viral rebound off-ART you will find out which group you were in. In the second part of the study, people in Group B can then have the active bNAbs.

Summary of RIO study design

Group A will receive active bNAbs in saline and stop ART. 

Group B will receive a placebo infusion of saline and stop ART. The placebo is an inactive infusion that looks the same as the bNAbs. 

After stopping ART you will be closely monitored every week for the first eight weeks. Monitoring will then continue every two weeks. 

The study will compare the time it takes for viral load to become detectable (viral rebound) in the two groups. Viral load is expected to rebound more quickly in people who received the placebo infusions than the bNAbs.

How is the study affected by coronavirus? 

To make sure that you are as safe as possible to stop ART while there is a risk of COVID-19, we will check that you do not have any symptoms of COVID-19 infection, just before you plan to stop taking your ART medicine. 

You will be tested for COVID-19 at the start of the study and this might happen again at future visits, if you develop symptoms. 

Your study doctor or nurse will also ask you some questions at each visit. They will take your temperature, to check if you have had any symptoms of COVID-19. If you have a positive test for COVID-19 while off ART your doctors will re-start your ARTs. 

All your study visits will take place in a safe COVID-19 free area of the hospital/s where no cases of COVID-19 will be seen. If you are unwell (COVID-19 positive or self-isolating) and cannot come to the hospital, we will try to arrange a home visit for the collection of HIV VL blood sample. If you have any questions about COVID-19 and your safety, then you can discuss it with the study team. 

If you do not wish to take part in the study due to COVID-19 then your care will not be affected.

How can I take part?

The RIO study is now recruiting in the UK and Denmark.

Please contact your local clinic or the participating clinical sites for more information.

The trial protocol is available from