A new HIV treatment developed by researchers at Imperial College London has enabled patients to remain drug-free for up to two years, offering a potential alternative to the daily pill that currently dominates management of the virus.
In a trial involving 68 participants, three quarters were able to stop taking antiretroviral therapy (ART) for five months, half could pause treatment for a year, and roughly a quarter achieved a drug-free period of two years. The results, published in The Lancet HIV, mark what scientists describe as the first time a therapy based on broadly neutralising antibodies (bNAbs) has shown viral load control of this duration and magnitude in a randomised, placebo-controlled study. Professor Sarah Fidler, of Imperial College London and a consultant HIV physician at St Mary’s Hospital, said: “These results open new possibilities for HIV treatment and bring us closer to our goal of finding a cure.”
Currently, the 113,500 people living with HIV in the UK rely on daily ART, a pill that prevents the virus from replicating but is not a cure. The therapy transformed HIV from a fatal diagnosis to a manageable condition by stopping progression to Aids, yet it costs the NHS more than £400m each year. The UK government has set an ambition to end new HIV transmissions by 2030 through increased testing, prevention awareness and efforts to tackle stigma. Latest surveillance data for 2024 shows new diagnoses falling by 4 per cent across the UK, from 3,169 in 2023 to 3,043 in 2024, though challenges remain: in England, 42 per cent of new cases in 2024 were diagnosed late, and certain groups — including young people aged 15–24, ethnic minorities and heterosexual men — remain harder to reach.
How the antibody therapy works
The experimental treatment is a mixture of two broadly neutralising antibodies (bNAbs) — immune proteins that act as a physical barrier to bacteria and viruses. Unlike standard ART, which blocks the virus’s replication machinery inside infected cells, bNAbs target conserved regions on the viral envelope, enabling them to neutralise a wide range of HIV strains. They also engage the host immune system through Fc effector functions, which may help clear infected cells. Crucially, researchers believe bNAbs can reduce the size of the HIV reservoir — the collection of latent infected cells that current ART cannot reach and which is a major obstacle to a cure.
The trial, known as the RIO study, was a collaboration between Imperial College London, the University of Oxford and Rockefeller University in New York. Participants were recruited from Britain and Denmark between 2021 and 2024 and assigned to receive either the bNAb drug or a saline placebo. The therapy proved more effective than placebo: primary results showed that three quarters of those receiving bNAbs controlled the virus off ART for more than 20 weeks. Further follow-up found that at 48 weeks, half of participants remained undetectable, and one third were still undetectable at 72 weeks — approximately one year after their last treatment. This suggests the potential for lasting HIV remission or long-term treatment-free control.
However, scientists acknowledge challenges. bNAb monotherapy can lead to resistance, so combination therapies — like the two-antibody mix used here — are essential to maintain suppression. Pre-existing resistance, high production costs and logistical complexities also need to be addressed. Other research in the field is exploring combinations of bNAbs with drugs such as lenacapavir, a capsid inhibitor. Gilead Sciences has received Breakthrough Therapy Designation for a combination regimen involving its own bNAbs (teropavimab and zinlirvimab) for potential twice-yearly dosing.
Future directions
Scientists behind the Imperial study now aim to extend the therapy’s antiviral effects so that a larger proportion of patients can benefit for longer. The development of bNAb-based treatments represents a significant shift towards long-term remission or even a functional cure — a goal that has been pursued for decades. Alongside this work, other avenues such as long-acting injectable therapies (including cabotegravir), gene editing approaches like CRISPR, and therapeutic vaccines are under investigation.
Professor Fidler, whose research focuses on novel therapies toward an HIV cure, emphasised that the results bring the field closer to a fundamental change in how the virus is managed. The drug-free periods achieved in the trial, if replicated and extended in larger studies, could free patients from the burden of daily medication and reduce the significant long-term costs of HIV care — estimated in the UK to range from £73,000 to £404,300 per person over a lifetime, with antiretroviral drugs accounting for roughly two thirds of that figure.
