Compound Profile
KPV Enters Cells Through PepT1, Not a Melanocortin Receptor
Published: August 25, 2026
TL;DR
KPV is the C-terminal tripeptide of alpha-MSH, residues 11 to 13, so the obvious place to look for its mechanism is a melanocortin receptor. The experiments point somewhere else. Dalmasso and colleagues found the peptide carried into cells by PepT1, a di- and tripeptide transporter. Eight years later, a colitis-associated-cancer study ran the cleanest version of that test: the effect appeared in wild-type mice and was absent in PepT1-knockout mice. In July 2026 FDA's compounding advisory committee recommended KPV for the 503A bulks list, 8 to 6 with one abstention, over the objection of FDA's own staff.
Curo lists this material as KPV 10 mg in the research peptide catalogue. Lot documents are searchable through the COA library, and catalogue materials are supplied for research use only.
The alpha-MSH fragment took a different path
The lineage sets an expectation. KPV is the tail end of a melanocortin hormone, so a melanocortin receptor is the first place anyone would look. A mouse peritonitis study looked there and came back with a negative: KPV's anti-migratory activity was not blocked by an MC3/4 receptor antagonist, and the peptide did not raise macrophage cAMP under the conditions tested.
That does not rule out every interaction with a melanocortin receptor. What it means is that the measured activity survived blockade of the pathway everyone would check first, which left the mechanism open until the intestinal-cell work supplied a positive answer.
Identity matters whenever results are compared across studies and lots. The guide to verifying a certificate against its lot covers that check. A related paperwork problem, for a peptide that carries a metal ion, is worked through in the GHK-Cu identity review.
PepT1 carried KPV into two cell types
Dalmasso and colleagues worked with Caco2-BBE intestinal epithelial cells and Jurkat T cells, and found PepT1-mediated KPV uptake in both. During IL-1beta stimulation of the Caco2-BBE cells, co-incubation with 10 nM KPV reduced NF-kappaB reporter activity and shifted I-kappaB-alpha degradation and phosphorylation kinetics. MAP kinase signalling changed as well, and pro-inflammatory cytokine secretion fell. The authors put all of it down to transporter-mediated uptake rather than melanocortin signalling.
Transporter kinetics differed between the two systems. Apparent hPepT1 Km was around 160 micromol/L in Caco2-BBE cells and around 700 micromol/L in Jurkat cells. Those are uptake constants measured in cell models, not a half-life, a bioavailability figure, or an exposure target in a living body. Nothing in this work measured absorption, distribution, metabolism or elimination in people.
Uptake in Jurkat cells widened the finding past the intestinal epithelium without making it tissue-independent, and the 10 nM figure describes a signalling change under IL-1beta stimulation. The work supports a PepT1-linked model in the cells tested. It does not make PepT1 the only route KPV can take in every tissue.
Curo's quality and testing standard sets out the documentation used for catalogue material.
The knockout result puts PepT1 at the center
Mouse protocols took the hypothesis out of the dish. In Dalmasso's DSS- and TNBS-induced colitis experiments the animals drank water containing 100 micromol/L KPV, and inflammatory readouts including colonic cytokine expression came down. KPV on its own changed neither basal colonic myeloperoxidase nor the other inflammatory parameters measured, which is an observation about those particular readouts rather than a safety finding.
A second 2008 paper widened the model set and, almost in passing, added another mark against the receptor explanation. Across DSS and CD45RBhi transfer-colitis models, the KPV arm showed reduced histologic inflammation and lower myeloperoxidase activity, and the authors reported effects in mice whose MC1R was non-functional. A melanocortin receptor being out of action did not remove the response.
The delivery work runs alongside the mechanism work. In TNBS-induced ulcerative colitis in rats, a KPV hydrogel administered rectally was reported to reduce symptoms and to improve epithelial-barrier, crypt and goblet-cell morphology. That is a formulation result in a rodent model, and it belongs to the same preclinical tier as everything above it.
The decisive experiment came later, in the AOM/DSS colitis-associated-cancer model. Wild-type and PepT1-knockout mice drank water containing 100 micromol/L KPV through two 7-day DSS cycles. Tumorigenesis-associated endpoints fell in the wild-type animals. In the knockouts the effect was simply absent. A second protocol in the same paper gave APCMin/+ mice that same 100 micromol/L drinking water from 5 to 18 weeks of age.
Take the transporter away and the effect goes with it. That is a different order of evidence from a shifted signalling marker, because it puts PepT1 in a causal position inside the model instead of merely alongside the outcome. The concentrations and schedules belong to those mouse studies and are not a human protocol.
Human skin, and a committee that voted against FDA's staff
The one human-tissue experiment on the record is about delivery, not effect. In microporated human skin studied ex vivo, passive KPV permeation stayed below the 0.01 microgram/mL detection limit, microneedle treatment produced 4.4 micrograms per square centimetre per hour, and electrically assisted conditions pushed permeation higher again.
Below a detection limit is not zero. It means passive movement could not be quantified beneath that threshold. The assisted-delivery figures show the method changed transport across excised tissue, and they stop there: no systemic bioavailability percentage, no human half-life, no participant.
A Federal Register notice put KPV free base and KPV acetate in front of FDA's Pharmacy Compounding Advisory Committee on July 23, 2026, under docket FDA-2025-N-6895, with wound healing and inflammatory conditions as the evaluated uses.
FDA's staff recommended against listing. The agency's briefing document for KPV reported no human data for products containing either form and unknown potential human safety risks. The committee disagreed. Voting separately on each form, it recommended both for inclusion by 8 in favor to 6 against with one abstention. Hyman, Phelps & McNamara reported the same 8-6-1 result for both forms, and Pharmaceutical Executive and Regulatory Focus reported the tally independently.
The recommendation is advisory. FDA is not bound by it, and a substance reaches the Section 503A bulks list through agency rulemaking rather than a committee vote. FDA's meeting page carries the briefing documents, the questions put to the committee and the archived broadcast, but no minutes or vote table, so the tallies rest on contemporaneous reporting.
BPC-157 sat on the same two-day agenda and arrives there with a much larger trial record behind it.
Common questions
Does KPV act through melanocortin receptors?
The strongest published experiments support a different route in the systems tested. MC3/4 antagonism did not block the anti-migratory effect in the mouse peritonitis study, Dalmasso attributed the cell effects to PepT1 uptake, and the later knockout experiment made the intestinal effect PepT1-dependent. The results do not establish one exclusive mechanism across every tissue.
What do KPV's apparent Km values mean?
They describe apparent PepT1 uptake kinetics in Caco2-BBE and Jurkat cell models. They are not measures of systemic human exposure, half-life, or bioavailability, and they do not convert into a human protocol.
Has KPV been studied in human participants?
The specified ClinicalTrials.gov searches for KPV and Lys-Pro-Val returned zero registered studies on August 25, 2026. The ex vivo skin work used excised human tissue and supplied no participant-level efficacy or safety results.
What did the July 2026 committee decide about KPV?
It recommended both the free base and the acetate for the Section 503A bulks list, 8 in favor to 6 against with one abstention on each form, for wound healing and inflammatory conditions. That is a non-binding recommendation to FDA, not an approval and not a listing. FDA staff had recommended against it.