A hydrocarbon double-stapled peptide called D26, based on HIV's own gp41 protein, can directly inactivate free HIV particles (not just block replication), resists enzymatic breakdown, has a long half-life, and remarkably shows detectable oral absorption.
Detectable oral absorptionexceptionally rare for a peptide drug — D26's double-staple design provides protease resistance enabling it to survive the digestive tract, plus extended half-life and HIV sanctuary site penetration
What the researchers found
The double-stapled peptide D26 efficiently inhibits HIV-1 infection and directly inactivates cell-free virions, with high protease resistance, extended in vivo half-life, enhanced sanctuary site penetration, and detectable oral bioavailability.
Why it matters
HIV can hide in sanctuary sites (brain, testes, gut tissue) where current drugs barely reach, contributing to the inability to cure the infection. A long-acting peptide that penetrates these sites, directly kills free virus, AND can potentially be taken orally would be a game-changer for HIV treatment — addressing multiple unmet needs simultaneously.
The numbers in context
Double-stapled peptide D26; based on gp41 LLP3 motif; inhibited HIV-1 infection and inactivated cell-free virions.
How the study worked
Designed and synthesized a hydrocarbon double-stapled helical peptide based on the HIV-1 gp41 LLP3 motif. Tested for HIV-1 inhibition, direct virion inactivation, proteolytic stability, pharmacokinetics (half-life), tissue distribution (sanctuary site penetration), and oral absorption compared to linear/non-stapled version.
Who was studied
Preclinical HIV-1 inactivation studies
What this study cannot tell us
Preclinical study — D26 has not been tested in humans. Oral bioavailability is described as 'detectable' not 'high' — it may not be sufficient for therapeutic dosing orally. Manufacturing double-stapled peptides at clinical scale is challenging and expensive. HIV resistance to D26 has not been assessed. Long-term safety of a gp41-derived peptide is unknown.
How to read the evidence
Preliminary — preclinical proof-of-concept with promising pharmacokinetic properties demonstrated in laboratory and animal studies, but no human clinical data yet.
When this study was published
Published in 2024 in Journal of Medicinal Chemistry, a top-tier journal for drug design and medicinal chemistry research.
The bigger picture
Peptide drugs have historically been limited by rapid breakdown in the body and inability to be taken orally. Double-stapling technology addresses both problems at once by locking the peptide into a protease-resistant helix. D26 demonstrates that stapled peptides can achieve what was once considered nearly impossible — oral bioavailability for a peptide therapeutic. Beyond HIV, this approach could revolutionize peptide drug delivery across many disease areas.
Questions still open
- Is D26's oral bioavailability high enough for therapeutic dosing, or will injectable formulations still be needed?
- Can HIV develop resistance to D26's virus-inactivation mechanism, given that it targets the virus's own structural protein?
- Could the double-stapling approach be applied to other antiviral peptides targeting different viruses?
Common questions
What does 'double-stapled' mean for a peptide?
Why is it important that D26 kills free virus particles?
Read the original research
Discovery of a Double-Stapled Short Peptide as a Long-Acting HIV-1 Inactivator with Potential for Oral Bioavailability.
Journal of medicinal chemistry, 67(12), 9991-10004
Citation
Wang, Chao; Zhang, Wenpeng; Xu, Ling; Tu, Jiahuang; Su, Shan; Li, Qing; Zhang, Tao; Zheng, Longbo; Wang, Huan; Zhuang, Xiaomei; Tang, Xuan; Yuan, Yu; Meng, Guangpeng; Lu, Lu; Xiao, Junhai; Wang, Qian; Jiang, Shibo. (2024). Discovery of a Double-Stapled Short Peptide as a Long-Acting HIV-1 Inactivator with Potential for Oral Bioavailability.. Journal of medicinal chemistry, 67(12), 9991-10004. https://doi.org/10.1021/acs.jmedchem.4c00150