# LL-37

LL-37 has 2 registered human trials. It is marketed for 4 different uses.

**In short**

- 2 registered human trials exist for LL-37.
- LL-37 is not FDA-approved for any use.
- What has actually been studied: diabetic foot ulcer, melanoma.
- Last checked against ClinicalTrials.gov on 2026-07-30.

## What it is

LL-37 is the only cathelicidin antimicrobial peptide made by the human body, a 37-residue helix cleaved from a precursor called hCAP18 and named for the two leucines it begins with. It is part of innate immunity: it both kills microbes directly and signals to the immune system.

## Where the claims come from

The science behind the interest is genuine, and it includes a well-known link to vitamin D, which increases the body’s own production of LL-37. That connection is often presented as evidence that supplementing the peptide will improve immunity or heal wounds, which is a different claim from the one the research supports.

## What evidence exists outside the registry

This is a compound where the registry count understates the human evidence. At least three controlled human trials have been published without a registry entry, covering venous leg ulcers, diabetic foot ulcers and an oral preparation studied against SARS-CoV-2. Separately, most trials that appear in a naive registry search do not administer LL-37 at all — they measure it as a marker in vitamin D studies.

**Sources for the above**

- [LL-37 in venous leg ulcers (Wound Repair Regen, 2021)](https://pubmed.ncbi.nlm.nih.gov/34687253/) — Multicentre randomised trial; published without a ClinicalTrials.gov registration.
- [NCT02225366 — intratumoral LL-37 in melanoma](https://clinicaltrials.gov/study/NCT02225366) — One of only two registered trials that administer the peptide.
- [FDA — bulk drug substances nominated but withdrawn](https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks) — Cathelicidin LL-37 appears in the withdrawn table.

## Approved for

Not approved by the FDA for any use. Nothing has been reviewed for safety, effectiveness or manufacturing quality.

## Studied for

- Diabetic Foot Ulcer
- Melanoma

## Marketed for

- Wound healing
- Antimicrobial
- Immune support
- Skin

## What regulators have said

LL-37 was nominated for use in pharmacy compounding and the nomination was withdrawn, so it is NOT on FDA's active list of substances that may present significant safety risks. FDA had published the concern below while it was under review.

FDA's own words: "Compounded drugs containing cathelicidin LL-37 may pose risk for immunogenicity for certain routes of administration and may have complexities with regard to peptide-related impurities and API characterization. FDA lacks sufficient safety-related information regarding cathelicidin LL-37."

Source: US Food and Drug Administration — https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
Checked 2026-07-30. This list changes.

This is a judgment about compounding and manufacturing, not a finding about whether LL-37 has any effect.


## Every trial on record

| Trial ID | Title | Condition | Phase | Status | Enrolled |
|---|---|---|---|---|---|
| [NCT04098562](https://clinicaltrials.gov/study/NCT04098562) | Efficacy of LL-37 Cream on Bacteria Colonization, Inflammation Response and Healing Rate of Diabetic Foot Ulcers | Diabetic Foot Ulcer | Phase 2 | UNKNOWN | 40 |
| [NCT02225366](https://clinicaltrials.gov/study/NCT02225366) | Intratumoral Injections of LL37 for Melanoma | Melanoma | Phase 2 | COMPLETED | 4 |

## Common questions

**How many human trials does LL-37 have?**
2, each listed above with a link to its original record.

**Is LL-37 FDA approved?**
No. It is not approved by the FDA for any indication.

**Where does this data come from?**
ClinicalTrials.gov. We count interventional human studies only. Every trial
links to its original record.

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*Automated aggregation from public registries. Not medical advice. No physician
has reviewed this page. Source: https://www.whatsactuallyknown.com/compounds/ll-37*