LL-37
Cathelicidin Antimicrobial Peptide LL-37 (hCAP18/LL-37)
Access and compounding status raise extra safety and legal questions.
The only antimicrobial peptide of its kind naturally produced in the human body, capable of fighting bacteria, viruses, and fungi while also helping regulate immune responses and promote wound healing. Human research includes a positive clinical trial for diabetic foot ulcers and an early-stage cancer trial, with more studies underway.
This entry is a cited research summary, not an established treatment reference. Dosing language is included as source context, not as medical instruction.
Safety Summary
Human adverse-event data are sparse. In the DFU RCT, no safety concerns were noted over 4 weeks of topical use (PMID 37480520). In the melanoma trial, no serious adverse events occurred in 3 patients over up to 8 weeks of intratumoral injection (NCT02225366). In the oral cas001 pilot, no adverse reactions were reported in 11 patients over 3 weeks (DOI 10.1101/2020.05.11.20064584). In preclinical rat toxicity testing at 100x clinical dose, no adverse effects on body weight, food intake, or blood parameters were observed (DOI 10.1101/2020.05.11.20064584). However, source reviews describe LL-37 as cytotoxic to multiple human cell types at 1-10 microM via caspase-independent AIF-mediated apoptosis, preferentially targeting infected/weakened cells (DOI 10.1007/s00011-025-02005-8). At very high concentrations (as in psoriatic lesions, up to 300 microM), LL-37 drives rosacea-like skin inflammation via NLRP3 activation (DOI 10.1007/s00011-025-02005-8). LL-37 triggers mast cell degranulation via MrgX2 receptors (DOI 10.1007/s00011-025-02005-8). FDA flags immunogenicity, peptide-related impurity concerns, limited safety information, possible detrimental male-reproductive effects, and protumorigenic findings in some tissues. LL-37 from macrophages promotes colorectal cancer cell proliferation via Wnt/beta-catenin pathway activation in vitro (PMID 29936765).
Clinical check-in
If real-world use or exposure is being considered, review potential interactions, contraindications, and monitoring needs with a licensed clinician rather than relying on summary copy alone.
Sources: [1-15]