Tifuvirtide
The second-generation fusion inhibitor: stronger than enfuvirtide in people whose virus had escaped it, abandoned before phase 3
Tifuvirtide (T-1249) is a 39-amino-acid synthetic peptide copied from a region of HIV-1's gp41 envelope protein. Like enfuvirtide, the first approved fusion inhibitor, it jams the machinery HIV uses to merge with a cell, and it was built to keep working where enfuvirtide had failed. In short studies it lowered viral load in heavily treated adults, including adults whose virus was more than a hundred times less susceptible to enfuvirtide. Its development was discontinued in 2004, before any phase 3 trial, and a later review attributes the halt to problems formulating the peptide rather than to a lack of activity.
Used in human trials: 6.25 to 192 mg/day, Daily, Subcutaneous (Trial: dose escalation in treatment-experienced adults) Details ↓
Recommended Dosing
Used in human trials
No manufacturer dose exists for this use: these are amounts given in published trials, not recommendations.
Work out syringe units → · New to syringes? · All dosing data ↓
What is it?
HIV cannot get into a cell without fusing its own envelope with the cell's membrane, and the protein that performs the merger is gp41. A peptide that copies part of gp41 can get in the way of that step by binding the stretch the protein needs to fold against itself. Enfuvirtide, approved in 2003 as Fuzeon, was the first drug built on that idea. Tifuvirtide was the next one: a 39-residue peptide, three residues longer than enfuvirtide and reaching a different part of the same region, developed by Trimeris and taken into people while enfuvirtide was still new.
The two peptides are close relatives with a meaningful difference in their make-up. Both carry a tryptophan-rich stretch at one end, which is what makes them stick to membranes. Only the longer peptide also carries the segment that binds the hydrophobic pocket of gp41, and that extra piece is the reason laboratory groups kept coming back to it: it binds its target harder, it goes into lipid membranes more readily, and it holds more of a helical shape in water.
Its first test in people was an open-label dose-escalation study in 115 adults with advanced HIV and long drug histories, who received the peptide on its own for a fortnight. Viral load fell further as the dose rose, by a median of almost two logs at the highest dose tried, and the problem that would follow the whole class showed up immediately: more than half of the participants reacted at the injection sites.
The study that made the case for a second fusion inhibitor came next. Fifty-three adults were enrolled while their HIV was replicating despite an enfuvirtide-containing regimen; their virus was on average more than a hundredfold less susceptible to enfuvirtide but only twofold less susceptible to the new peptide. They swapped one injection for the other and kept everything else the same, and over ten days viral load fell by a median of 1.26 logs. That is the clearest evidence the class can be sequenced, in the sense that failing one fusion inhibitor does not use up the next.
The longer picture was less flattering. Patients from that programme rolled over into 48 weeks of continued dosing, and the early drop of about 1.5 logs faded to about half a log by the end of the year, while susceptibility fell to roughly ninety-fold below the starting point. Resistance accumulated in the same short stretch of gp41 that enfuvirtide resistance uses, residues 36 to 45, with a substitution at position 50 appearing in about a third of the patients.
Laboratory work filled in why. Growing virus in the presence of rising concentrations selected changes at gp41 position 38, the same position that drives enfuvirtide resistance but with different replacement residues; a virus resistant to the newer peptide was always resistant to enfuvirtide, while the reverse did not hold. A systematic scan of the binding site found that only charged substitutions produced resistance to it, where almost any change produced resistance to enfuvirtide, and none produced resistance to the third-generation peptide that followed. Several studies also found that escape came at a price in viral fitness, though one resistant variant replicated as well as wild-type virus and still killed CD4 cells in human tonsil tissue.
Two other lines of research used it without ever giving it to a person. A Lisbon group spent a decade comparing how the two fusion inhibitors behave at membranes, with fluorescence, atomic force microscopy and simulations, and found the longer peptide binds blood cell membranes about eight times more strongly and disturbs them more. Separately, a formulated gel protected macaques from vaginal infection with three different hybrid viruses, which made it a candidate microbicide; a later group tried to build a slow-release vaginal ring around it. None of that work resumed after the drug programme stopped.
The programme itself ended in 2004. A journal news note recorded the discontinuation of clinical development that year, lay-press newsletters reported the same thing as it happened, and a 2013 review of the class states that the clinical evaluation was halted because of a formulation problem rather than a failure of effect. No phase 3 trial was ever run, no regulator has ever reviewed it, and the one trial still listed on ClinicalTrials.gov is the rollover study, last updated in 2005. Peptides offered for sale under this name sit outside any regulated supply, and nothing is known about what a vial sold that way contains.
Mechanism of Action
HIV-1's gp41 protein pulls the viral and cell membranes together by folding one of its helical regions against another. A peptide copying the second of those regions binds the first one while it is exposed and prevents the fold, so fusion never completes. Tifuvirtide binds a stretch that overlaps enfuvirtide's but is not the same, which is why virus that has escaped enfuvirtide often remains susceptible to it.
Binds gp41's HR1 region
It occupies a part of the HR1 region that overlaps enfuvirtide's target and extends into the hydrophobic pocket, so the six-helix bundle that drives fusion cannot form (PMIDs 19617355, 17428857).
Works outside the cell
Because it acts before entry, it blocked the transfer of virus from dendritic cells into CD4 T cells without blunting virus-specific T cell responses (PMID 18367527).
Sticks to membranes
It partitions into lipid membranes and adsorbs to cholesterol-rich ones, binding blood cell membranes about eight times more strongly than enfuvirtide, which concentrates it where fusion happens (PMIDs 15535700, 20352107).
A narrower route to resistance
In cell culture only charged substitutions at the binding site conferred resistance, where almost any substitution conferred resistance to enfuvirtide (PMID 19617355).
Resistance still arrives
Over 48 weeks of dosing, susceptibility fell about ninety-fold as changes accumulated in gp41 residues 36 to 45 and at position 50 (PMID 18184079).
Published Research
These are studies of tifuvirtide (T-1249) itself, read from their PubMed abstracts: three studies that gave it to people, a plasma assay built for it, a macaque protection study and a cell study of virus hand-off between immune cells, resistance selection and binding-site work in cell culture, susceptibility of HIV-1 groups M and O, a synergy experiment with the other fusion inhibitors, four studies of how it behaves at membranes, a vaginal ring formulation, and two reviews of the class. Studies of enfuvirtide, of the third-generation peptide T-2635 and of lipopeptides built from this sequence are listed under References.
First study in people: 115 adults, 14 days, dose escalation
An open-label phase 1/2 study gave the peptide alone, by injection under the skin, to 115 adults with HIV-1 for two weeks at daily doses from 6.25 mg to 192 mg. The group was heavily treated, with a median CD4 count of 57 cells per microlitre and a median of eleven previous antiretroviral drugs. No dose-limiting toxicity appeared. Viral load fell further at higher doses: the median largest fall from baseline ranged from 0.29 log10 copies/mL in the lowest dose group to 1.96 log10 in the highest. Injection-site reactions were the most common adverse event, in 57% of participants.
Adults whose virus had escaped enfuvirtide: 53 patients, 10 days
Adults with detectable virus while taking an enfuvirtide-containing regimen replaced enfuvirtide with 192 mg of this peptide daily and left the rest of the failing regimen in place. Measured against the susceptibility of fusion-inhibitor-naive virus, their isolates were 116-fold less susceptible to enfuvirtide but only 2-fold less susceptible to the new peptide. Over ten days the median viral load fell by 1.26 log10 copies/mL, and 73% of patients fell by at least one log. Neither baseline susceptibility measure predicted who responded. Injection-site reactions, mostly mild, occurred in 64%.
A year of dosing: the early gain faded and resistance accumulated
Patients who had completed the ten-day study rolled over into continued dosing, with envelope genotype and phenotype measured at weeks 8, 16 and 48. The median viral load fall was about 1.5 log10 copies/mL at week two but only about 0.5 log10 at 48 weeks. Susceptibility drifted from 1.8-fold to about 93-fold below the fusion-inhibitor-naive baseline, alongside further change in gp41 residues 36 to 45, most often G36D or N43K, with a substitution at position 50 in about a third of patients and some changes in the second heptad repeat.
A plasma assay built to measure it
Researchers developed and validated a liquid chromatography-tandem mass spectrometry method that measures enfuvirtide, this peptide and one enfuvirtide breakdown product in human plasma, using deuterated versions of each peptide as internal standards. The assay was linear from 20 to 10,000 nanograms per millilitre for both fusion inhibitors, with precision and accuracy within 13%, and it worked on plasma from patients taking enfuvirtide. The method exists because peptide drugs of this size are awkward to measure, and it is the kind of groundwork a drug programme needs.
A gel protected macaques from vaginal infection
Formulated as a simple gel and applied vaginally, the peptide protected macaques against high-dose challenge with three hybrid simian-human viruses that use different coreceptors, and against a simian virus as well. Half the animals were protected at interpolated concentrations of roughly 40 to 130 micromolar and all were protected at 0.1 to 2 millimolar. In cells, 1 micromolar blocked all 48 viruses of a panel regardless of coreceptor use or genetic subtype, and across 636 envelope-pseudotyped viruses from clinical samples the concentrations halving infection clustered around 10 nanomolar.
It blocked virus hand-off from dendritic cells to T cells
In cocultures of dendritic cells and T cells, virus moved to the contact points between the two cell types within minutes. Adding the peptide did not stop dendritic cells capturing virus or releasing it at those contacts, but it did block the transfer into CD4 T cells and the amplification that follows, with higher amounts needed when mature dendritic cells drove the process. It did not interfere with the stimulation of virus-specific T cell responses, which is what a candidate microbicide would need.
Resistance selected in culture lands on gp41 position 38
Virus passaged in rising concentrations acquired changes in the HR1 region of gp41, most often replacing valine 38 with glutamate or arginine, in 10 of 19 cultures. Both changes were confirmed to cause resistance to this peptide and cross-resistance to enfuvirtide and to the peptide C34, but not to the third-generation inhibitor T-2635. Changes at residues 79 and 90 gave modest resistance to both this peptide and T-2635. Position 38 is the same residue behind enfuvirtide resistance, with different replacements, so the two drugs inhibit in very similar ways.
Only charged substitutions made virus resistant to it
A mutational scan of the peptide binding site in gp41 tested three generations of fusion inhibitors against the same panel. Most substitutions produced resistance to enfuvirtide; only charged amino acids produced resistance to this peptide; none produced resistance to the third-generation peptide T-2635. Comparing the results with structural modelling, the authors sorted resistance into four mechanisms: reduced contact, steric obstruction, electrostatic repulsion and electrostatic attraction. The narrow route to resistance is the clearest laboratory argument for the second-generation design.
Resistance usually cost the virus its fitness, but not always
Sixteen codons of the gp41 binding region were randomized to see where virus can tolerate change. Only positions 37, 38 and 40 accepted substitutions. Passaging those randomized viruses under pressure from this peptide produced highly resistant forms, all with changes in the same motif, and the more resistant a virus was, the less fit and less damaging it tended to be. One exception matters: a variant with roughly tenfold reduced susceptibility grew like wild-type virus and still depleted CD4 cells in ex vivo human lymphoid tissue, with or without the drug present.
HIV-1 group O was less susceptible to it than to enfuvirtide
Isolates from HIV-1 groups M and O were tested against both fusion inhibitors. Group O isolates, which are rare and genetically distant from the group M viruses behind most of the pandemic, turned out to be as sensitive to enfuvirtide as group M viruses but usually less sensitive to this peptide. The authors read that as a sign that natural differences in gp41 may blunt second-generation fusion inhibitors in some lineages, and it cuts against the assumption that the newer peptide is simply stronger everywhere.
Natural gp41 variants that blunt enfuvirtide did not blunt it
Ten sequence variations found in the gp41 binding region of untreated patients were engineered into a laboratory virus. Most did not reduce how well the virus infected cells. Three of the ten, including the L33V change common in subtype D isolates, reduced sensitivity to enfuvirtide about fivefold. None of the ten conferred resistance to this peptide. Natural variation that matters for the first-generation drug therefore need not matter for the second.
Combining fusion inhibitors was strongly synergistic in cells
Mixing enfuvirtide with this peptide, or with the third-generation peptide T-1144, suppressed HIV-1-driven membrane fusion at doses two to three orders of magnitude lower than either drug needed alone, a synergy the authors scored at the strong end of the standard index. The same synergy held against laboratory and patient-derived strains, including enfuvirtide-resistant ones. The explanation offered is that the three peptides carry different functional segments and bind different primary sites in gp41, so they can act cooperatively.
A sequence comparison across HIV-1 group O and HIV-2
The authors aligned the relevant membrane-spanning region of HIV-1 group O and HIV-2 isolates to predict susceptibility on paper. They found wide genetic diversity in both binding regions, enough to compromise enfuvirtide against HIV-2 and group O, but the parts of gp41 that matter for this peptide were comparatively conserved in group O, which they took as a sign of broader activity across HIV-1 variants. For HIV-2 they expected neither peptide to work. This is prediction from sequence, not measurement.
It goes into membranes, and sticks to cholesterol-rich ones
Fluorescence experiments with artificial vesicles measured how readily the peptide leaves water for a lipid membrane. It partitioned strongly into fluid phosphatidylcholine membranes, sitting at the interface rather than deep inside, with a free energy change of -7.0 kilocalories per mole, and it was mostly disordered in that setting. Cholesterol cut the partitioning sharply, but energy transfer measurements showed the peptide adsorbing to those stiffer membranes instead. The authors suggested this membrane behaviour helps concentrate it where fusion happens.
About eight times more avid for blood cell membranes than enfuvirtide
Using a dye that reports changes in a membrane's electrical dipole, the authors watched both fusion inhibitors bind the membranes of human red blood cells and peripheral blood mononuclear cells. Both lowered the dipole potential in proportion to concentration, and quantifying the effect put the affinity of this peptide for cell membranes about eightfold above enfuvirtide's. Vesicles made to model those membranes gave the same answer. Stronger membrane binding, they argue, speeds and increases its delivery to gp41 before fusion begins.
Simulations show more hydrogen bonds, including to cholesterol
Molecular dynamics runs of 100 nanoseconds placed the peptide at phosphatidylcholine membranes with and without cholesterol. It interacted with both, locally rearranging the membrane surface where it sat, and formed hydrogen bonds with several groups on the lipids. Compared with enfuvirtide in the same setup it interacted more, most clearly in the cholesterol-containing membranes, because more of its residues could donate and accept hydrogen bonds, including bonds with cholesterol itself, which enfuvirtide did not form at all.
No fixed shape in water, but more helix than enfuvirtide
Both fusion inhibitors are usually drawn as helices, by analogy with the gp41 sequence they copy, yet such a helix would be unstable in water. Simulations of both peptides in water, alongside two shorter homologous peptides with no antiviral activity, found no stable structure over the time studied and a solvent-exposed surface that changed considerably during each run. The authors read that as several accessible shapes rather than one. This peptide was considerably more helical than enfuvirtide, which they link to its greater potency.
Microscopy of what it does to a supported membrane
Atomic force microscopy paired with fluorescence microscopy compared both fusion inhibitors on supported lipid bilayers with separated fluid, gel and ordered phases. At 15 micromolar this peptide roughened the membrane surface, reduced its fluidity, thinned the fluid regions and disrupted the borders of the gel regions, while enfuvirtide did much less. The authors attribute the difference to its two functional segments working together, the hydrophobic one and the amphipathic pocket-binding one that enfuvirtide lacks.
The extra binding segment explains the stronger membrane effects
This simulation study asked what the two fusion inhibitors do to the lipids themselves, in fluid and in cholesterol-ordered membranes. Both changed measurable structural and dynamic properties of the bilayers, and the longer peptide generally changed them more when adsorbed at the surface. The authors tie that to its having both the tryptophan-rich segment and the pocket-binding segment, where enfuvirtide has only the first, and note that interaction with both the cell membrane and the viral envelope is part of how these peptides work.
A vaginal ring designed to release it slowly
Conventional silicone vaginal rings release large peptides poorly, so this group built rings holding separate rods in which the peptide was dispersed with a water-attracting excipient: sodium chloride, sodium glutamate, lactose or zinc acetate. Rods immersed in simulated vaginal fluid gained weight and swelled to different degrees depending on the excipient, and release of the peptide improved with lactose, sodium chloride or sodium glutamate. The work was formulation research toward a microbicide, years after the treatment programme had been abandoned.
Making kilograms of a 39-residue peptide
A review from the company developing both fusion inhibitors sets out how the peptides were manufactured, which for a 36- and a 39-residue drug given by injection was the central practical problem. The route combined solid-phase synthesis of fragments with condensation of those fragments in solution, plus the analytical controls needed to keep a process of that size reliable. The review describes this peptide as active against viruses that become resistant to enfuvirtide, written while its clinical programme was still running.
A class review that records why it stopped
Reviewing peptide inhibitors of gp41-driven fusion, the author places this peptide as the representative second-generation compound and states plainly that its clinical evaluation was halted because of a problem with drug formulation, not for lack of antiviral effect. The same review describes how easily enfuvirtide resistance arises in cells and in patients, and which later peptides were in trials at the time. It is the clearest published statement of why a drug that worked in two short studies went no further.
The 2004 note recording the discontinuation
A one-page news item in AIDS Reviews, indexed in PubMed without an abstract, reports under its own title that clinical development of the fusion inhibitor was discontinued. It is cited here for the date and the fact, which the lay-press notes of the same months and the later class reviews agree on; it carries no results of its own.
Dosing Data
There is no label and no approved product, so the only amounts that exist are the ones used in its two short human studies. They are recorded here because they are published, not as a protocol: the drug was given as monotherapy or inside a failing regimen, under trial monitoring, and its development stopped more than twenty years ago.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no label and no published test that says what forms or vial sizes Tifuvirtide is sold in. A vial's own label is a seller's claim, not a source.
Mixing a vial: a worked example
No worked example: none of the doses on this page is a fixed amount in mg or mcg injected under the skin or into a muscle (the routes given are: subcutaneous). There is no home-mixing step to show. The reconstitution calculator does the arithmetic for any vial.
Source: the route and amount of each dose row in Dosing Data below.
Storage before and after mixing
Unknown: no label or published stability study on file says how to store Tifuvirtide, before or after mixing. The mixing guide sets out the general rules, with their sources: keep a mixed vial in the fridge, and use it promptly, as the bacteriostatic water label says of any drug dissolved in it. The 28 days often quoted is the limit for an opened multiple-dose vial from a manufacturer, an outer limit set for sterility, not a time a mixed solution has been shown to keep. Nobody has published how long Tifuvirtide stays intact once mixed.
How it is taken
As it was given in human studies: Subcutaneous (Daily; Trial: dose escalation in treatment-experienced adults).
For injection technique, sites and needle disposal, see the mixing guide.
Source: Used in human trials: the route and frequency of each row in Dosing Data below.
What to expect, and when
How long it stays in the body: not established by a measurement cited on this entry.
How long the doses were given: Trial: dose escalation in treatment-experienced adults: 14 days; Trial: adults with virus replicating on enfuvirtide: 10 days, continued to 48 weeks in the rollover study.
When effects appear: unknown; no source on this page gives a time to effect for Tifuvirtide. Results reported in the studies are under Published Research.
Source: Used in human trials, the duration of each row in Dosing Data below.
Side effects, and when to stop or get help
From the Side Effects section: Injection-site reactions in 57% of 115 patients in the first study, and in 64% of 53 patients in the second, where they were described as generally mild (PMIDs 14999611, 15747252); No dose-limiting toxicity was identified up to 192 mg a day over 14 days (PMID 14999611); Loss of effect with continued dosing: the viral load fall shrank from about 1.5 log10 at week two to about 0.5 log10 at 48 weeks as resistance accumulated (PMID 18184079); No study examined it beyond 48 weeks, and none enrolled children, pregnant women or people without HIV. Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Tifuvirtide. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“From the three studies that gave it to people”).
Interactions
Unknown: a PubMed search for human interaction studies of Tifuvirtide (reviewed 2026-11-04) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Tifuvirtide products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder; it checks the measured mass against Tifuvirtide's expected mass, 5,036.6 Da, from this entry's molecular data. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: Discontinued (Never approved). Sport: Prohibited (S0 catch-all).
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
From the three studies that gave it to people. The total human experience is about 170 patients, most of them for two weeks.
Contraindications & Cautions
There is no label to quote and no approved use, so these are limits on what is known rather than formal contraindications.
Legal Status
An investigational drug whose development stopped in 2004. It was never approved anywhere and no application for it is on file.
Frequently Asked Questions
?What is tifuvirtide?
A 39-amino-acid synthetic peptide copied from HIV-1's gp41 envelope protein, developed as T-1249 after enfuvirtide. It blocks the step where HIV fuses with a cell. It reached phase 1/2 studies and was dropped in 2004.
?How is it different from enfuvirtide?
It is three residues longer and binds an overlapping but different part of the same region of gp41, including a hydrophobic pocket enfuvirtide does not reach. In practice that meant virus which had escaped enfuvirtide usually stayed susceptible to it.
?Did it work in people?
In two short studies, yes. Viral load fell by up to about two logs over 14 days of monotherapy, and by a median of 1.26 logs over ten days in people whose virus was replicating on enfuvirtide. Over 48 weeks the effect faded as resistance grew.
?Why was it discontinued?
A 2013 review of the class states that its clinical evaluation was halted because of a formulation problem, and a 2004 journal note records the discontinuation. Nothing published points to a safety finding or a loss of antiviral activity as the reason.
?Is it approved or available anywhere?
No. Drugs@FDA holds no record, the European Medicines Agency's database holds no entry, and no trial has recruited since the rollover study closed. Material sold under this name comes from no regulated supply.
?Was it ever a candidate for HIV prevention?
It was studied as one. A gel protected macaques from vaginal infection with several viruses, and a group later tried to formulate it into a slow-release vaginal ring. Neither line reached a human prevention trial.
References
- [other] PubChem CID 16130644 (tifuvirtide, T-1249): 39-residue sequence WQEWEQKITALLEQAQIQQEKNEYELQKLDKWASLWEWF, N-acetylated and C-terminally amidated, molecular formula C235H341N57O67, molecular weight 5037. Read November 4, 2026. https://pubchem.ncbi.nlm.nih.gov/compound/16130644
- [fda] US FDA, Drugs@FDA and the drug label endpoint (openFDA): no record for tifuvirtide or T-1249. Read November 4, 2026.
- [other] European Medicines Agency, medicines database: no entry for tifuvirtide. Read November 4, 2026.
- [clinical-trial] ClinicalTrials.gov NCT00048217 (T1249-105), "A Rollover Study to Provide Chronic T-1249 to Patients Who Completed Study T1249-102", sponsor Trimeris, phase 1/2, first posted October 30, 2002, record last updated June 24, 2005, overall status unknown (last known: active, not recruiting). The only registered study of T-1249. Read November 4, 2026.
- [pubmed] Eron JJ, et al. "Short-term safety and antiretroviral activity of T-1249, a second-generation fusion inhibitor of HIV." J Infect Dis, 2004;189(6):1075-83. PMID: 14999611.
- [pubmed] Lalezari JP, et al. "T-1249 retains potent antiretroviral activity in patients who had experienced virological failure while on an enfuvirtide-containing treatment regimen." J Infect Dis, 2005;191(7):1155-63. PMID: 15747252.
- [pubmed] Melby T, et al. "Evolution of genotypic and phenotypic resistance during chronic treatment with the fusion inhibitor T-1249." AIDS Res Hum Retroviruses, 2007;23(11):1366-73. PMID: 18184079.
- [pubmed] van den Broek I, et al. "Development and validation of a quantitative assay for the measurement of two HIV-fusion inhibitors, enfuvirtide and tifuvirtide, and one metabolite of enfuvirtide (M-20) in human plasma by liquid chromatography-tandem mass spectrometry." J Chromatogr B Analyt Technol Biomed Life Sci, 2006;837(1-2):49-58. PMID: 16713406.
- [pubmed] Veazey RS, et al. "Tropism-independent protection of macaques against vaginal transmission of three SHIVs by the HIV-1 fusion inhibitor T-1249." Proc Natl Acad Sci U S A, 2008;105(30):10531-6. PMID: 18647836.
- [pubmed] Frank I, et al. "A fusion inhibitor prevents spread of immunodeficiency viruses, but not activation of virus-specific T cells, by dendritic cells." J Virol, 2008;82(11):5329-39. PMID: 18367527.
- [pubmed] Eggink D, et al. "Selection of T1249-resistant human immunodeficiency virus type 1 variants." J Virol, 2008;82(13):6678-88. PMID: 18434391.
- [pubmed] Eggink D, et al. "Detailed mechanistic insights into HIV-1 sensitivity to three generations of fusion inhibitors." J Biol Chem, 2009;284(39):26941-50. PMID: 19617355.
- [pubmed] Chinnadurai R, et al. "Human immunodeficiency virus type 1 variants resistant to first- and second-version fusion inhibitors and cytopathic in ex vivo human lymphoid tissue." J Virol, 2007;81(12):6563-72. PMID: 17428857.
- [pubmed] Chinnadurai R, et al. "Inhibition of HIV-1 group M and O isolates by fusion inhibitors." AIDS, 2005;19(16):1919-22. PMID: 16227804.
- [pubmed] Chinnadurai R, et al. "Effect of naturally-occurring gp41 HR1 variations on susceptibility of HIV-1 to fusion inhibitors." AIDS, 2005;19(13):1401-5. PMID: 16103771.
- [pubmed] Pan C, et al. "Combinations of the first and next generations of human immunodeficiency virus (HIV) fusion inhibitors exhibit a highly potent synergistic effect against enfuvirtide- sensitive and -resistant HIV type 1 strains." J Virol, 2009;83(16):7862-72. PMID: 19493996.
- [pubmed] Poveda E, et al. "Are fusion inhibitors active against all HIV variants?." AIDS Res Hum Retroviruses, 2004;20(3):347-8. PMID: 15117459.
- [pubmed] Veiga AS, et al. "HIV fusion inhibitor peptide T-1249 is able to insert or adsorb to lipidic bilayers. Putative correlation with improved efficiency." J Am Chem Soc, 2004;126(45):14758-63. PMID: 15535700.
- [pubmed] Matos PM, et al. "HIV-1 fusion inhibitor peptides enfuvirtide and T-1249 interact with erythrocyte and lymphocyte membranes." PLoS One, 2010;5(3):e9830. PMID: 20352107.
- [pubmed] Martins do Canto AM, et al. "Molecular dynamics simulation of HIV fusion inhibitor T-1249: insights on peptide-lipid interaction." Comput Math Methods Med, 2012;2012:151854. PMID: 22675399.
- [pubmed] Martins Do Canto AM, et al. "T-20 and T-1249 HIV fusion inhibitors' structure and conformation in solution: a molecular dynamics study." J Pept Sci, 2008;14(4):442-7. PMID: 18069719.
- [pubmed] Franquelim HG, et al. "Decoding distinct membrane interactions of HIV-1 fusion inhibitors using a combined atomic force and fluorescence microscopy approach." Biochim Biophys Acta, 2013;1828(8):1777-85. PMID: 23500616.
- [pubmed] Martins do Canto AM, et al. "Effect of amphipathic HIV fusion inhibitor peptides on POPC and POPC/cholesterol membrane properties: a molecular simulation study." Int J Mol Sci, 2013;14(7):14724-43. PMID: 23860208.
- [pubmed] Murphy DJ, et al. "Sustained release of the candidate antiretroviral peptides T-1249 and JNJ54310516-AFP from a rod insert vaginal ring." Drug Deliv Transl Res, 2016;6(3):234-42. PMID: 26787615.
- [pubmed] Schneider SE, et al. "Development of HIV fusion inhibitors." J Pept Sci, 2005;11(11):744-53. PMID: 16130177.
- [pubmed] He Y. "Synthesized peptide inhibitors of HIV-1 gp41-dependent membrane fusion." Curr Pharm Des, 2013;19(10):1800-9. PMID: 23092277.
- [pubmed] Martin-Carbonero L. "Discontinuation of the clinical development of fusion inhibitor T-1249." AIDS Rev, 2004;6(1):61. PMID: 15168742.
- [pubmed] "T-1249 development hits a snag." AIDS Clin Care, 2004;16(2):15. PMID: 15032178.
- [pubmed] Huff B. "T-1249 development suspended." GMHC Treat Issues, 2003;17(12):6. PMID: 15011643.
- [pubmed] Eggink D, et al. "Resistance of human immunodeficiency virus type 1 to a third-generation fusion inhibitor requires multiple mutations in gp41 and is accompanied by a dramatic loss of gp41 function." J Virol, 2011;85(20):10785-97. PMID: 21835789.
- [pubmed] Reeves JD, et al. "Enfuvirtide resistance mutations: impact on human immunodeficiency virus envelope function, entry inhibitor sensitivity, and virus neutralization." J Virol, 2005;79(8):4991-9. PMID: 15795284.
- [pubmed] Zhu Y, et al. "Exceptional potency and structural basis of a T1249-derived lipopeptide fusion inhibitor against HIV-1, HIV-2, and simian immunodeficiency virus." J Biol Chem, 2018;293(14):5323-5334. PMID: 29425101.
Sources & Citations
Every study on this page was read from its PubMed abstract on November 4, 2026. Regulatory status comes from Drugs@FDA (openFDA), the European Medicines Agency's medicines database and ClinicalTrials.gov, read the same day; the formula and mass come from PubChem CID 16130644. Grey Peptides sells nothing and links to no vendor.
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