What This Article Covers
This article summarizes published research on LL-37 for technical review. It separates direct human evidence, review-level context, and animal or mechanistic work so the reader can see what was actually tested before seeing the limitations.
Bottom Line
LL-37 has direct human wound-study evidence in hard-to-heal venous leg ulcers, but the results are context-specific and mixed. A small first-in-human randomized study reported improved healing signals at two topical concentrations, while a later larger phase IIb randomized study did not show a significant improvement in the full study population and found signals only in post hoc subgroup analysis.
What Was Tested in Humans?
A 2014 first-in-human randomized, placebo-controlled clinical trial enrolled 34 participants with hard-to-heal venous leg ulcers. After a placebo run-in period, participants entered a four-week randomized double-blind phase with twice-weekly topical LL-37 at 0.5, 1.6, or 3.2 mg/mL, or placebo. The 0.5 mg/mL and 1.6 mg/mL groups showed faster healing-rate signals than placebo, while the 3.2 mg/mL group did not show a similar benefit. The authors reported no local or systemic safety concerns in that small study [pubmed:25041740].
A later multicenter phase IIb double-blind randomized placebo-controlled trial evaluated topical LL-37 with compression therapy in 148 patients with hard-to-heal venous leg ulcers. In the full study population, the study did not identify a significant healing improvement versus placebo. A post hoc subgroup analysis suggested improvement in patients with large target wounds, but post hoc results should be treated as exploratory and hypothesis-generating [pubmed:34687253].
What Do Reviews and Evidence Syntheses Add?
Reviews of cathelicidin biology place LL-37 within innate immunity, antimicrobial-defense, inflammation, and wound-response research. That context helps explain why LL-37 has been studied, but it does not replace the direct clinical evidence above and does not establish generalized outcomes outside the wound-study setting.
What Did Animal and Mechanistic Studies Show?
Mechanistic work generally treats LL-37 as a human cathelicidin-derived antimicrobial peptide with immunomodulatory and wound-response functions. Those studies are useful for hypothesis generation, but mechanism alone does not establish clinical efficacy, dosing, route, safety, or generalizability.
How the Evidence Fits Together
The practical reading for LL-37 is evidence hierarchy. Human studies carry the most weight, but only for the exact population, route, comparator, and endpoint studied. In LL-37, the human evidence is strongest for topical venous-leg-ulcer research and remains too narrow to support broader conclusions.
What Is Not Established
- Broad human efficacy for LL-37 is not established by the selected literature.
- The venous-leg-ulcer studies do not establish outcomes for other tissues, models, routes, populations, or product types.
- Post hoc subgroup findings should not be presented as definitive proof.
- Dosing, administration, treatment, diagnostic, or veterinary-use guidance is outside the scope of KRL materials.
Research-Use Boundary
This article summarizes published research and regulatory-source discussion for technical review. It is not medical advice, not a dosing guide, and not a recommendation for human or veterinary use. KRL materials are sold for research use only and are not for diagnostic, therapeutic, or administration purposes.
Selected Sources
- [pubmed:25041740] Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial. https://pubmed.ncbi.nlm.nih.gov/25041740/
- [pubmed:34687253] Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: A multicentric prospective randomized placebo-controlled clinical trial. https://pubmed.ncbi.nlm.nih.gov/34687253/
- PubMed search context for LL-37/cathelicidin review literature: https://pubmed.ncbi.nlm.nih.gov/?term=LL-37+cathelicidin+review
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