LL-37 vs KPV

What is being compared?

LL-37 is the 37-amino-acid active peptide processed from the human cathelicidin precursor hCAP18. Its antimicrobial and immune-signaling effects have been studied in laboratory systems. KPV (Lys-Pro-Val) is the C-terminal tripeptide motif of alpha-MSH; direct KPV experiments have examined inflammatory signaling and intestinal-cell uptake. A result for the full parent hormone is not automatically a KPV result. LL-37 identity, PMID 8681941 · KPV colitis and uptake experiment, PMID 18061177

The grades describe the limits of therapeutic claims, not a numerical ranking of the peptides or a head-to-head result. The trial and experimental sources behind the table are described below.

What human LL-37 studies found

In a randomized 34-person pilot for hard-to-heal venous leg ulcers, selected lower-concentration topical LL-37 groups showed improved healing measures. A later 148-person phase IIb venous-ulcer trial found no significant healing benefit in the full population; its favorable large-ulcer subgroup analysis was post hoc. These are separate treated populations, and the pilot signal does not override the larger trial’s overall result. Grönberg et al., 2014, PMID 25041740 · Mahlapuu et al., 2021, PMID 34687253

A randomized trial of native LL-37 cream in mildly infected diabetic foot ulcers reported improved granulation measures, but no significant reduction in measured inflammatory markers or aerobic bacterial colonization. Its NCT04098562 registration and publication describe the same participants, not two independent efficacy studies. Miranda et al., 2023, PMID 37480520

A separate completed melanoma registry record, NCT02225366, reports intratumoral LL-37 in four people and posted outcomes with very small group denominators. No separate journal outcome paper for that cohort was identified in the reviewed sources. These posted results cannot establish antitumor efficacy or general safety. This registry cohort is distinct from the three published topical wound populations.

An open-label COVID-19 study tested engineered Lactococcus lactis expressing LL-37, not purified native peptide. Its overall time-to-negative-viral-test comparison was not significant; an early-treatment subgroup signal cannot be transferred to topical or injected LL-37. Zhao et al., 2023, PMID 37605995

What direct KPV studies found

Dalmasso and colleagues studied KPV uptake and inflammatory pathways in human-derived cell lines and mouse colitis models. Oral KPV reduced colitis readouts in mice; that is not a human oral-bioavailability or treatment result. Another preclinical study reported anti-inflammatory effects without requiring melanocortin-receptor signaling in its tested models. The evidence does not establish that KPV treats inflammatory bowel disease, skin inflammation, or infection in people. Dalmasso et al., 2008, PMID 18061177 · Getting et al., 2003, PMID 12750433

No controlled KPV treatment trial or human drug-exposure dataset was identified in the scoped review. FDA says it has identified no human exposure data for KPV drug products by any route and lacks the information needed to assess harms of administration. This is a limit on what is known, not proof that a product is safe or unsafe. FDA compounding safety review

Why their mechanisms do not predict a clinical winner

LL-37 can act against microbes in laboratory assays, yet the diabetic-foot-ulcer trial did not significantly reduce measured bacterial colonization. Its immune effects also vary by setting: human rosacea tissue and laboratory psoriasis work implicate cathelicidin-related signaling in inflammation. KPV’s anti-inflammatory and PepT1-uptake findings come from experimental models. Neither mechanism alone establishes a broad benefit, a preferred use, or a safe LL-37–KPV combination. Miranda et al., 2023, PMID 37480520 · Yamasaki et al., 2007, PMID 17676051 · Lande et al., 2007, PMID 17873860 · Dalmasso et al., 2008, PMID 18061177

FDA lists both LL-37 and KPV among withdrawn bulk-drug nominations; withdrawal does not itself establish an approved use. FDA describes insufficient safety information for compounded LL-37 and no identified human KPV drug-product exposure data. The topical LL-37 trial results cannot be generalized to other formulations or routes. FDA compounding safety review

This comparison summarizes selected research, not a treatment recommendation. Neither peptide has established clinical benefit for the broad immune or infection claims discussed here.