LL-37 Peptide
Your body makes exactly one cathelicidin. This is it, all 37 residues, and its lead clinical candidate did not clear phase 2b.
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For research use only. Not for human or veterinary use.
What LL-37 Peptide is
The plain-language version, first.
One family, one member. Humans make a single cathelicidin and this is the whole roster.
LL-37 is a 37 amino acid cationic peptide and the only cathelicidin produced by humans, released by proteinase 3 from the 170 residue precursor hCAP18 and acting on bacterial membranes through charge based disruption. Its clinical candidate form ropocamptide failed a phase 2b trial, the sponsor was subsequently liquidated, and the compound has been flagged by the FDA.
Some animals carry a dozen of these. Cows have a small library. Pigs have several.
Humans make one.
One cathelicidin. That is the entire human roster, and LL-37 is it.
It does not start life as LL-37. It gets cut out of a larger precursor protein called hCAP18 by an enzyme, proteinase 3, and the 37 residues that come off are the active part.
So the name is literal in a way names in this field usually are not. Two leucines at the start, thirty-seven residues long. Somebody named it after what it looks like on paper.
A cationic peptide that your own neutrophils are releasing right now, sold here as a research material, and studied almost entirely on skin rather than anywhere else.
What is LL-37?
Mechanism studied, not outcome promised.
Strong positive charge draws it to the more negatively charged membranes of bacteria. Selective, but not absolutely so.
It is cytotoxic to mammalian cells not far above its antimicrobial range. That gap is why it has never been given systemically to a person.
It punches holes in membranes and it also talks to your cells. Two jobs, one peptide.
Look, most antimicrobial peptides do one thing and it is a fairly blunt thing. They are positively charged, bacterial membranes are negatively charged, and physics does the rest.
LL-37 does that. It also does something considerably more interesting.
It signals. It talks to your own cells, influences how they move, and behaves like a messenger rather than just a weapon.
That dual character is why it turns up in immunology papers and dermatology papers and cancer-biology papers, which is a strange spread for a molecule this small.
The research that reached clinic went at epithelial migration, which is why the trial work sat on skin rather than anywhere systemic.
Here's the honest part. A molecule that does two different things is harder to develop, not easier, because now you have two mechanisms and two sets of consequences.
Everything clinical here has been topical. Not injection, not systemic administration, and the distinction is not a technicality.
The research so far for LL-37 Peptide
Where the evidence is thin, we say so.
Roughly 226 people across all registered studies. Topical on venous leg ulcers, or injected directly into melanoma tumours in a four-person study.
Any systemic administration. Any subcutaneous dosing. Any phase 3. There is no human data outside skin and tumour.
A 34-patient trial was positive. The 148-patient phase IIb that followed found no significant improvement over placebo. In both, the lowest dose outperformed the highest. Promore Pharma entered voluntary liquidation in October 2023 with ropocamptide named as its main remaining asset.
The trial exists, it was well run, and it did not deliver. All three matter.
There is a real trial here, it was properly run, and it is worth reading rather than summarising.
Mahlapuu and colleagues, 2021. The HEAL LL-37 trial: 148 patients, phase IIb, double-blind, three arms, fifteen sites in Poland.
In the authors' own words, it did not identify any significant improvement in tissue repair in patients treated with LL-37 as compared with the placebo.
Read that carefully, because it is the useful kind of negative. A well-designed trial that reports honestly is worth more than three positive papers with fifteen animals each.
There is one other trial on the record, NCT02225366 at MD Anderson, which went in a completely different direction and is not about the same question at all.
So the file is: strong basic science, one good clinical trial that did not deliver, and a lot of internet enthusiasm that has not caught up with either.
We would rather tell you the trial did not work than hope you never look it up.
Have a look at the vial sizes we have in stock.
LL-37 Peptide specs
The chemistry, exactly as released.
Who studies LL-37 Peptide
Who tends to order this one, and why.
A research compound does not have one audience. It has a handful of rooms where the same question keeps coming up, and the question is a different question in each of them.
Wound repair
Chronic venous leg ulcers, the indication both clinical trials targeted, always topical and always alongside compression therapy.
Innate immunity
Cathelicidin biology, neutrophil function and the antimicrobial peptide field generally. This is the human reference molecule.
Dermatology and autoimmunity
Lande and colleagues found roughly two-thirds of moderate to severe plaque psoriasis patients carry T cells specific for LL-37.
Vitamin D researchers
The vitamin D response element in the human gene sits in a primate-specific element absent from mouse, rat and dog, so this pathway has no rodent model.
Sold for laboratory research only. This is not guidance for personal use, and nothing here is a recommendation.
LL-37 Peptide backstory
How it got here.
Cathelicidins are an ancient family and most mammals carry several. Humans carry one, and it took until the nineties to characterise it properly.
The therapeutic interest came from wounds. Chronic venous leg ulcers are colonised, slow to close, and expensive, and an endogenous peptide that both kills bacteria and promotes epithelial migration was an obvious candidate.
Promore Pharma in Sweden took it forward as ropocamptide through two clinical trials. The 2021 phase IIb was the decision point and it did not deliver.
The company liquidated two years later, describing ropocamptide as its main remaining asset.
- 1
The only one we have
Most mammals carry several cathelicidins. Humans carry one, cut from the hCAP18 precursor by proteinase 3 in neutrophils.
- 2
Into the clinic as ropocamptide
Promore Pharma in Sweden ran two topical trials in chronic venous leg ulcers, the second with 148 patients across Poland and Sweden.
- 3
Failed, then liquidated
The 2021 phase IIb showed no significant improvement over placebo. The company entered voluntary liquidation in October 2023.
Buying LL-37 Peptide in Canada
What ships, how fast, and the paperwork.
The hard part of buying research material is almost never the compound. It is the logistics. What leaves the building, how fast it moves, and what is in the box beside the vial. Here is ours, plainly.
Same day out of British Columbia
Our building, our cold packs, our people, and nothing sitting in a customs queue while you refresh a tracking page.
Then into the fridge
Keep it cold and keep it dark. Sealed and freeze-dried it handles a rough trip without ice. Once it lands, fridge.
FDA has published a concern
Cathelicidin LL-37 sits on the FDA list of bulk drug substances that may present significant safety risks, in the withdrawn-nomination section. FDA cites nonclinical findings suggesting detrimental effects on male reproduction and that the substance can be protumorigenic in some tissues. We would rather you read that here than not at all.
Stuff people ask about LL-37 Peptide
If your question is not here, email us. Real human answers.
No. The HEAL LL-37 phase IIb trial published in 2021 randomised 148 patients with hard-to-resolve venous leg ulcers across 15 sites. The authors state it did not identify any significant improvement in healing compared with placebo. A smaller 34-patient trial in 2014 had been positive at the low dose.
No. Every human exposure in the registered record has been topical application to a wound or direct injection into a tumour, roughly 226 people in total. There is no systemic or subcutaneous human dosing data for LL-37 at all.
Nobody has explained it, and it happened twice. In the 2014 trial 0.5 milligrams per millilitre gave a repair rate about six times placebo while 3.2 milligrams per millilitre was no better than placebo. The 2021 trial showed the same inversion. That pattern is a reason for caution about the mechanism as understood.
Cathelicidin LL-37 appears on FDA list of bulk drug substances that may present significant safety risks, in the section for nominations that were withdrawn. FDA stated concern that nonclinical research findings suggest detrimental effects on male reproduction and that the drug can be protumorigenic in some tissues.
The 37 residue sequence is the same. But in the body it is one member of a family: UniProt annotates seven further cleavage products from the same hCAP18 precursor, including LL-29, LL-23, KS-30 and KR-20. Endogenous LL-37 activity is the sum of that mixture, not one molecule in isolation.
Because the vitamin D response element in the human gene promoter sits inside a primate-specific genetic element that the mouse, rat and dog genomes do not carry. Gombart and colleagues reported that induction was not observed in murine cells. The pathway exists in primates and not in the standard laboratory rodents.
Good pairing options with LL-37 Peptide
What researchers stack alongside it.
Pairing is where research gets ahead of itself. These are the compounds researchers put in the same order as LL-37 Peptide, which is a statement about ordering habits, not about evidence. Two things in one cart have not been studied together unless somebody studied them together.
BPC-157's arginate salt sibling. Same fifteen residues, different packaging, and a published literature of its own that rounds to zero.
Three research compounds sharing one vial: BPC-157, GHK-Cu and TB-500, plus a copper atom with an open coordination site. No published study on the combination.
Order LL-37 Peptide right now
One last look before you decide.
Freeze-dried, COA on the page, ships cold
If you are researching LL-37 Peptide and you want a source you do not have to second-guess, start with the paperwork on this page. For research use only.
Not for human consumption. Not approved by Health Canada or any other regulatory body.
Page last updated August 19, 2026
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