Adipotide (FTPP) Research: What Published Studies Have Investigated

What is adipotide?

What is adipotide? It is a chimeric peptidomimetic — a designed molecule built from two functional halves joined by a short linker. In the primary literature it is written as CKGGRAKDC-GG-(D)(KLAKLAK)₂, and it is also catalogued as FTPP and, in the one registered clinical study, as Prohibitin Targeting Peptide 1.

The two halves do different jobs. CKGGRAKDC is a homing sequence: a nine-residue motif, flanked by cysteines, that Kolonin and colleagues isolated by in-vivo phage display and reported as associating with prohibitin on the blood vessels of white adipose tissue. (D)(KLAKLAK)₂ is a proapoptotic sequence built from D-amino acids, a well-known cationic amphipathic peptide that disrupts mitochondrial membranes once it is inside a cell but is comparatively inert outside one. The -GG- in the middle is a glycine-glycine linker.

The design logic is therefore address plus payload. The molecule is not intended to do anything by itself; it is intended to be delivered somewhere by its first half and to act only where its second half is taken up. Whether that intent was realised is exactly the question the literature below argues about, and it is why this page spends as much space on the objections as on the findings.

Discovery and origin in the literature

Phage display, and an address for fat

The origin paper is Kolonin, Saha, Chan, Pasqualini and Arap, Nature Medicine, 2004 (PMID 15133506), from the Arap and Pasqualini laboratory then at the University of Texas MD Anderson Cancer Center. That group had spent years building a method — in-vivo phage display — for reading the molecular addresses written on the surface of blood vessels in different organs. A library of bacteriophage, each displaying a different short peptide, is introduced into a living animal; the phage that stick to a chosen tissue are recovered and re-amplified; after several rounds, the surviving peptide sequences are the ones that home to that tissue.

Applied to white fat, the method returned the sequence CKGGRAKDC. The paper then reported the second step, which is the harder one: identifying what the peptide binds. Kolonin and colleagues reported that CKGGRAKDC associates with prohibitin, a multifunctional membrane protein, and proposed prohibitin as a vascular marker of adipose tissue. Coupling the homing motif to the proapoptotic (D)(KLAKLAK)₂ sequence produced the molecule this page is about, and in that 2004 paper the authors reported ablation of white fat and reversal of established obesity in their mouse model.

Why it drew attention

Two features made the work unusually visible. First, the target was the vasculature rather than the adipocyte — the strategy borrowed directly from tumour anti-angiogenic thinking and applied it to fat. Second, the same paper reported that prohibitin is expressed in the blood vessels of human white fat, which is what let the authors write that the work “may lead to” targeted drugs for obesity. That conditional phrasing is the authors’ own, and it is worth preserving here, because a great deal of subsequent internet writing about this compound dropped it.

Reference data

The values below are from the public chemical record (PubChem CID 163360068) and the sequence given in the primary papers. They describe identity and physical form only.

One analytical caveat belongs with that table. The homing motif is a cysteine-flanked loop of the CX₇C type used in the phage libraries it came from, so the disulfide state of the two cysteines is a genuine structural variable, and the PubChem entry is recorded in a form with free thiols. That is a matter for the certificate of analysis rather than a settled property, and it is discussed in the verification section below. No reconstitution procedure, quantity or route is given or implied anywhere on this page.

Mechanisms researchers have examined

The adipotide mechanism literature is organised around the two-part design. Each point below is what studies proposed or measured in defined model systems:

• Ligand-directed homing to adipose vasculature — the phage-display selection that produced CKGGRAKDC, and its reported association with prohibitin as an adipose-vascular marker (Kolonin 2004, PMID 15133506).
• Prohibitin as the docking protein — prohibitin is a widely expressed, multifunctional membrane and mitochondrial protein. The 2004 paper reported its presence on adipose-tissue blood vessels; its wide expression elsewhere is one of the reasons selectivity has remained a live question rather than a settled one.
• Mitochondrial disruption by (D)(KLAKLAK)₂ — this cationic amphipathic sequence is used across the targeted-therapy literature precisely because it is poorly active extracellularly and disrupts mitochondrial membranes once internalised. It is the payload, not the address.
• Apoptosis in white-adipose blood vessels — Barnhart and colleagues (2011, PMID 22072637) reported targeted apoptosis within the blood vessels of white adipose tissue in obese monkeys, with reduction in white adipose tissue confirmed by magnetic resonance imaging and dual-energy x-ray absorptiometry.
• A competing explanation: reduced food consumption — Criscione’s 2012 comment (PMID 22539771) argued that the weight change reported in the monkey study may reflect a direct effect on food consumption rather than the vascular-ablation mechanism proposed. Kim and colleagues (2012, Diabetes, PMID 22733798) separately reported that glucose-tolerance improvement induced by a peptide of this design was rapid and weight-independent in their rodent model, a finding that complicates a simple “less fat, better metabolism” account.

The fifth bullet is not a footnote. In this literature the mechanism is contested in print, and a page that reported only the founding hypothesis would be reporting half the record.

Research findings by area

The rodent work

Kolonin and colleagues (2004) reported resorption of established white adipose tissue and normalisation of metabolism in their mouse model, and described the result as obesity reversal without detectable adverse effects in that model. Subsequent rodent work from other groups examined the same targeting strategy in different delivery formats — Hossen and colleagues (2013, J Control Release, PMID 23871959) compared nanoparticle-targeted constructs against bioconjugates of this kind — and Kim and colleagues (2012) used a peptide of this design to probe whether the metabolic changes could be separated from the weight change at all.

The primate study, reported in full

Barnhart and colleagues (2011, Science Translational Medicine, PMID 22072637) is the paper that made adipotide widely known, and it is the one that must be reported completely. The study evaluated the compound in obese Old World monkeys. The authors reported targeted apoptosis within the blood vessels of white adipose tissue, rapid weight loss, improved insulin resistance, and a marked reduction in white adipose tissue confirmed by two independent imaging methods.

The same abstract also states that at the experimentally determined optimal doses, monkeys from three different species displayed predictable and reversible changes in renal proximal tubule function. That sentence belongs beside the efficacy sentence, not underneath it. The proximal tubule is the segment of the nephron that reabsorbs filtered solute, and a compound that alters its function is acting on the kidney. “Predictable and reversible” is the authors’ characterisation, reported here as theirs; it is a description of what they observed at the doses they used, not an assurance about anything.

The published objection

In April 2012 Science Translational Medicine published a comment by Criscione (PMID 22539771) proposing that the reported weight loss may instead reflect a direct effect of the compound on food consumption. The journal record shows an author reply alongside it. This is normal scientific argument and it is included because it is part of the primary record for this molecule — a reader evaluating adipotide should know that the headline mechanism was challenged in the same journal within six months.

Research models and evidence status

The honest summary is short. Adipotide is a laboratory compound whose development stopped.

What the record consists of

Mouse and rat models; one primate study; a published mechanistic challenge to that primate study; and a scattering of delivery-format papers from independent groups. That is the substance. There is no phase 2 or phase 3 programme, no regulatory submission anywhere, and no approved product.

The human record: one terminated trial

ClinicalTrials.gov lists NCT01262664, “A First-in-Man, Phase I Evaluation of A Single Cycle of Prohibitin Targeting Peptide 1 in Patients With Metastatic Prostate Cancer and Obesity”, sponsored by MD Anderson Cancer Center. The registry record shows a phase 1 design, an actual enrolment of four participants, a status of TERMINATED with the stated reason “Terminated per PI’s request”, and no results posted. Searching the registry for “adipotide” returns nothing at all. No human efficacy or safety publication for this compound exists in the indexed literature.

What is not established

Almost everything a reader might want to know. It is not established that the vascular-ablation mechanism is what produced the weight change in primates — that was disputed in print and never resolved. It is not established that the renal changes seen in three monkey species would be predictable or reversible under any other conditions, and the observation itself is the single most important safety-relevant fact in the file. It is not established that prohibitin targeting is selective enough in a whole organism to matter, given how widely prohibitin is expressed. There are no human pharmacokinetic data, no human dose-finding data, no human safety data, and no independent replication of the primate result. Nothing on this page is an efficacy, therapeutic, metabolic, weight-related or other use claim of any kind, and the material is supplied for laboratory research use only — not for human or veterinary use.

Why the page says so plainly

Compounds with a striking animal result and no completed human programme attract more confident writing than the evidence supports. Adipotide is a clear case: a well-designed molecule, a genuinely interesting targeting idea, a documented organ-toxicity signal in primates, and a programme that stopped. All four of those facts are the story.

How to verify this compound yourself

Adipotide is a chemically awkward molecule to make and an awkward one to certify, which makes the paperwork unusually informative:

• Mass-spec identity against a large expected mass — at roughly 2557 Da this is a long synthetic chain by peptide standards, and long chains accumulate deletion sequences. Mass spectrometry is what confirms the intended species is the dominant one, and the expected mass is the number to check the certificate against.
• Disulfide state of the CKGGRAKDC loop — two cysteines can be free or oxidised to a loop, and the two forms differ by two hydrogen atoms. A certificate that reports only a purity percentage without an identity mass leaves that ambiguity unresolved.
• D-amino-acid content — the (KLAKLAK)₂ block is specified as D-amino acids. Ordinary reversed-phase HPLC does not distinguish D from L residues; a chain built with the wrong stereochemistry can pass a purity assay and still be a different molecule. This is a synthesis-documentation question, and it is the one most worth asking about for this compound in particular.
• HPLC purity — reversed-phase chromatography separates full-length product from truncations and from the deletion sequences that long syntheses generate; the percentage on the certificate is the summary of that separation.
• Counter-ion documentation — synthetic peptides are usually isolated as a salt, commonly trifluoroacetate, which affects net peptide content per unit mass. A documentation point rather than a purity one, but it should appear.

See how to read a COA for what each certificate line means, and how to verify peptide purity for how the methods fit together. The exact batch received can be checked on the self-serve verify tool.

Research-grade sourcing and verification

Adipotide is not held in stock. It appears on our sourcing catalogue as available to order — our supplier lists it, we have not bought it, and material of this kind typically takes about two to three weeks to reach us. For laboratory research use only, it is supplied with a per-batch Certificate of Analysis reporting HPLC purity (%) and mass-spec identity confirmation, verifiable at the lot level. For an adjacent metabolic-research small molecule with an entirely separate literature, see 5-Amino-1MQ research; for another injectable adipocyte-directed agent in active clinical development, see CBL-514 research. This is sourcing and quality-assurance framing only.

Frequently asked questions

Literature cited

1. Kolonin MG, Saha PK, Chan L, Pasqualini R, Arap W. “Reversal of obesity by targeted ablation of adipose tissue.” Nature Medicine. 2004;10(6):625–632. PMID 15133506. pubmed.ncbi.nlm.nih.gov/15133506.
2. Barnhart KF, Christianson DR, Hanley PW, et al. “A peptidomimetic targeting white fat causes weight loss and improved insulin resistance in obese monkeys.” Science Translational Medicine. 2011;3(108):108ra112. PMID 22072637. pubmed.ncbi.nlm.nih.gov/22072637.
3. Criscione L. “Comment on ‘A peptidomimetic targeting white fat causes weight loss and improved insulin resistance in obese monkeys’.” Science Translational Medicine. 2012;4(131):131le2 (author reply 131lr2). PMID 22539771. pubmed.ncbi.nlm.nih.gov/22539771.
4. Kim DH, Sartor MA, Bain JR, et al. “Rapid and weight-independent improvement of glucose tolerance induced by a peptide designed to elicit apoptosis in adipose tissue endothelium.” Diabetes. 2012;61(9):2299–2310. PMID 22733798. pubmed.ncbi.nlm.nih.gov/22733798.
5. Hossen N, Kajimoto K, Akita H, Hyodo M, Harashima H. “A comparative study between nanoparticle-targeted therapeutics and bioconjugates as obesity medication.” Journal of Controlled Release. 2013;171(2):104–112. PMID 23871959. pubmed.ncbi.nlm.nih.gov/23871959.
6. ClinicalTrials.gov. “A First-in-Man, Phase I Evaluation of A Single Cycle of Prohibitin Targeting Peptide 1 in Patients With Metastatic Prostate Cancer and Obesity.” NCT01262664 — phase 1, MD Anderson Cancer Center, enrolment 4 (actual), status terminated, no results posted. clinicaltrials.gov/study/NCT01262664.
7. National Center for Biotechnology Information. “PubChem Compound Summary for CID 163360068, Adipotide.” pubchem.ncbi.nlm.nih.gov/compound/163360068 (formula, mass, CAS 859216-15-2).