LL-37 (Cathelicidin) for Antimicrobial Defense & Wound Healing — Immunity
Only human cathelicidin antimicrobial peptide. Phase 2b wound healing data. Phase 1 melanoma data. Broad-spectrum antimicrobial. NOT FDA-approved.
Overview
LL-37 is the only human cathelicidin antimicrobial peptide — a 37-amino acid cationic peptide with broad-spectrum activity against bacteria, viruses, fungi, and biofilms. Beyond antimicrobial effects, LL-37 demonstrates immunomodulatory, wound healing, anti-inflammatory, and angiogenic properties. CLINICAL STATUS: Strongest evidence for TOPICAL wound healing (Phase 2b HEAL trial with 148 patients for hard-to-heal venous leg ulcers). Phase 1 melanoma trial (NCT02225366) showed safety and immune stimulation with intratumoral injections. ANTIMICROBIAL POTENCY: MIC <10 mcg/mL against MRSA, multi-drug resistant bacteria, with >4 log biofilm reduction. Synergistic with conventional antibiotics. CHALLENGES FOR SYSTEMIC USE: Short plasma half-life, susceptibility to proteases, reduced activity in high-salt environments, and dose-dependent cytotoxicity at higher concentrations. Most viable near-term application is topical formulations for chronic wounds at 0.5-1.6 mg/mL. Subcutaneous use for systemic immune support remains experimental with no established clinical protocols.
Indications
- Chronic wound healing (Phase 2b data - venous leg ulcers, 68% size reduction)
- Diabetic foot ulcer healing (clinical study data)
- Broad-spectrum antimicrobial defense (MRSA, MDR bacteria, viruses, fungi)
- Biofilm disruption (>4 log reduction in established biofilms)
- Melanoma immunotherapy (Phase 1 - intratumoral injection, immune stimulation)
- Angiogenesis promotion via FPRL1 receptor (wound healing and tissue repair)
- Synergistic antibiotic enhancement (increases membrane permeability)
- Immune modulation and inflammatory regulation
Mechanism of Action
Bacterial infections (including MRSA and MDR organisms), chronic non-healing wounds, or established biofilms resist conventional antibiotic treatment
Dosing
| Compound | Dose | Frequency | Notes |
|---|---|---|---|
| LL-37 | 0.5-1.6 mg/mL solution | Twice weekly for 4 weeks | Phase 2b clinical data. Most established route. Best response at 0.5-1.6 mg/mL range. |
| LL-37 | 100-200 mcg | Once daily for 2-4 weeks | EXPERIMENTAL - no clinical SC protocols exist. Start low, titrate by 50 mcg every 1-2 weeks. |
Evidence Grade
GRADE B
Safety & Contraindications
- CRITICAL: NOT FDA-approved for any indication
- Topical use generally well-tolerated in clinical trials
- Systemic (SC) use: LIMITED safety data, potential for allergic reactions
- Dose-dependent CYTOTOXICITY to human cells at higher concentrations (hemolysis)
- Short plasma half-life - susceptible to protease degradation
- Reduced antimicrobial activity in high-salt environments and plasma
- High production cost limits clinical scalability
- Dual role in cancer: both anticancer AND pro-tumorigenic effects depending on context
- Autoimmune concerns: biomarker for SLE activity, can contribute to autoimmune pathology
- Drug interactions: synergistic with many antibiotics, reduced activity with heparin
- SC dosing protocols are EXTRAPOLATED - no established clinical SC protocols exist