TaiMed Biologics has published Phase 1b/2a results for its long-acting dual-antibody HIV regimen, with 80% of participants maintaining viral suppression at 24 weeks.

TaiMed Biologics has published clinical data in The Lancet HIV showing that its investigational dual-antibody regimen maintained viral suppression in 16 of 20 participants with HIV after they stopped oral antiretroviral therapy (ART).

The Phase 1b/2a study evaluated TMB-365 and TMB-380 as a long-acting maintenance treatment for adults whose HIV was suppressed on oral ART. The findings were also presented at HIV Glasgow 2026.

The Phase 2a results showed that 16 of 17 participants with available Week 24 data in the per-protocol analysis maintained HIV-1 RNA below 50 copies/mL, equivalent to 94%. In the intention-to-treat population, 16 of 20 participants, or 80%, were suppressed at the same time point.

No participant met the study’s criteria for confirmed virologic failure.

Two antibodies target different stages of HIV entry

TMB-365 is a long-acting monoclonal antibody that targets the CD4 receptor on human cells, which HIV uses to enter and infect them. TMB-380 is a broadly neutralising antibody that targets the CD4-binding site of the HIV-1 gp120 protein.

The combination is designed to block viral entry through complementary host- and virus-targeting mechanisms, without relying on a small-molecule antiretroviral component.

In the Phase 2a study, participants stopped oral ART and received 4,800 mg of each antibody intravenously every eight weeks for 24 weeks. The study did not require pretreatment susceptibility screening for either antibody.

The Phase 1b portion enrolled 30 participants, while a further 20 people entered Phase 2a. The study was conducted at six clinical sites in the USA.

Safety and dosing findings inform Phase 2b

Treatment-emergent adverse events in Phase 2a were mild or moderate. Researchers reported no serious adverse events, deaths, Grade 3 or 4 adverse events, opportunistic infections or acute infusion reactions. Mean CD4 cell counts remained stable during treatment.

Three participants experienced temporary increases in HIV-1 RNA to approximately 200–300 copies/mL, followed by re-suppression. All three weighed more than 90 kg and had lower exposure to TMB-365.

Exploratory analyses identified bodyweight as a factor affecting TMB-365 exposure. The findings informed the introduction of bodyweight-based dosing in the subsequent Phase 2b study.

The study also reported improvements in selected measures of treatment satisfaction, including convenience, flexibility and compatibility with participants’ lifestyles.

“The ability to maintain viral suppression in most participants for 24 weeks with a complete antibody regimen is encouraging, particularly given that participants were enrolled without pretreatment susceptibility screening,” said Martin Markowitz, medical director of TaiMed Biologics and lead author of the publication.

“The ongoing Phase 2b study is designed to build on these findings in a larger population and provide a more rigorous assessment of the regimen’s potential as long-acting maintenance therapy.”

Larger study will assess longer-term potential

TaiMed is developing TMB-365/TMB-380 as a maintenance regimen for people with HIV who have achieved viral suppression on ART. The investigational treatment is intended to reduce reliance on daily oral medication through intravenous administration every two months.

The ongoing Phase 2b study will evaluate the combination in a larger population and provide further evidence on its efficacy, safety and pharmacokinetic profile.

The Phase 1b/2a findings provide early evidence that a complete antibody-based regimen could maintain viral suppression after oral ART is discontinued. However, the small Phase 2a population, short follow-up period and open-label design mean that larger studies are needed to establish whether the approach can offer a reliable long-term alternative to existing HIV maintenance treatment.

The regimen remains investigational and has not been approved by any regulatory authority.