Broadly Neutralizing Antibodies Present Promise in Modulating HIV Rebound After Treatment Interruption
Preliminary data from the ongoing RIO trial, presented at the 2026 Conference on Retroviruses and Opportunistic Infections (CROI), suggest that broadly neutralizing antibodies (bNAbs) may alter the dynamics of viral rebound in individuals living with HIV who discontinue antiretroviral therapy (ART). While not a cure, these findings offer early evidence that immune-based interventions could play a role in controlling the virus after treatment cessation.
Understanding the RIO Trial
The RIO trial is a randomized, controlled study investigating the use of two long-acting broadly neutralizing antibodies – 3BNC117-LS and 10-1074-LS – in individuals who began ART early after HIV infection and have achieved sustained viral suppression. The trial began recruiting participants in 2024 and presented initial results in March 2025 [RIO Trial Website].
Broadly neutralizing antibodies work by binding to conserved regions of the HIV envelope, preventing the virus from entering cells and potentially enhancing the immune system’s ability to clear infected cells. The “LS” modification extends the antibodies’ half-life, allowing them to remain in the circulation for a longer period.
Study Design and Findings
Participants in the RIO trial were randomized to receive either dual bNAbs or a placebo. The study included analytically supervised treatment interruptions (ATI), conducted under strict safety criteria. In the first phase of ATI (ATI-1), viral rebound was observed in all participants, as expected when ART is stopped.
In the placebo arm, viral rebound was rapid and universal, with all participants meeting the criteria for rebound by week 10 of ATI-1. Rebound was defined as either exceeding 1,000 copies/mL for six consecutive weeks or surpassing 100,000 copies/mL for two consecutive weeks [CROI 2025 Poster].
Preliminary data presented at CROI 2026 indicate that exposure to bNAbs may alter the way the virus rebounds following treatment interruption in some individuals [Life4me+ News Story]. Researchers noted that bNAb therapy was associated with an intact reservoir half-life decay approximately seven to eight times faster than previously reported estimates [CROI 2025 Poster].
Important Considerations
Researchers emphasize that these findings do not represent a cure for HIV and do not support individuals interrupting their ART outside of a clinical trial setting. The results presented at CROI 2026 represent only a portion of the ongoing RIO study, and further mechanistic analyses are underway to better understand these observations.
Looking Ahead
The RIO trial continues to investigate the potential of broadly neutralizing antibodies as a means of modulating viral control in people living with HIV. Further research is needed to determine the long-term effects of bNAb therapy and its potential role in future HIV treatment strategies. The 2026 CROI conference, held February 22-25 in Denver, Colorado, featured numerous presentations on HIV research and treatment advances [CROI 2026 Conference Materials].