First findings from RIO study shared by community representative on HIV i-Base

Posted on by Maathini Balachandran

Simon Collins, HIV i-Base community representative for the RIO study, provides a comprehensive summary and insightful commentary on the initial findings presented at the CROI 2025 conference.

Image taken from HIV i-Base

RIO is a randomised (1:1) placebo-controlled study looking at whether participants receiving two LS-bNABs (Arm A) could maintain viral load suppression off-ART during an analytic treatment interruption (ATI), for longer than participants who received a placebo (Arm B). Criteria to restart ART during the ATI included viral load >1000 copies/mL for six weeks or confirmed >100,000 copies/mL. The primary outcome included the time to loss of viral suppression up to week 20.

All participants were cisgender men, median age 39 years (range:  22 to 58), 85% were white British, with three Black and three Asian participants. Median CD4 count at baseline was 800 cells/mm3 (range: 272 to 1468).

Although previous studies have shown that bNAbs can sustain viral suppression, this is the first study to show a post-bNAbs vaccine-like immune response. People who received bNABs developed stronger immune activation markers compared to participants receiving the placebo and these enhanced immune responses against HIV were associated with greater viral load suppression.

These results included one participant who experienced viral load rebound during an ATI but not sufficiently high to meet the criteria to restart ART. Instead, viral load spontaneously resuppressed to undetectable levels and viral suppression has now been maintained for more than 18 months off-ART.

Simon comments “these exciting early results are the first randomised placebo-controlled data showing a significant impact of bNAbs on maintaining viral load for more than a year in some participants and a possible case where this vaccine-like effect might generate HIV remission. The next step in analyses that are already ongoing is to try to understand why only some participants experience such potent and durable responses.”

Read the full article here