Adipotide (FTPP)

Adipotide, also designated FTPP (Fat-Targeted Pro-apoptotic Peptide), is a chimeric peptidomimetic developed at the University of Texas MD Anderson Cancer Center by Dr. Wadih Arap and Dr. Renata Pasqualini. It consists of two functional domains joined by a short linker: a targeting sequence (CKGGRAKDC) that binds prohibitin on adipose tissue vasculature, and a pro-apoptotic D-amino acid sequence (KLAKLAK)2 that destroys the cells it enters. The overall molecular weight is approximately 2.5 kDa.

The mechanism of action exploits a fundamental vulnerability of adipose tissue: its dependence on dedicated blood supply. Prohibitin is a ~30 kDa protein expressed on the luminal surface of endothelial cells in blood vessels specifically supplying white adipose tissue (WAT). The CKGGRAKDC targeting peptide was identified through in vivo phage display screening in obese mice, where billions of random peptide sequences were injected intravenously and those that homed to fat vasculature were recovered and sequenced. Once the targeting peptide binds prohibitin on adipose endothelial cells, the chimeric peptide is internalized by receptor-mediated endocytosis. The (KLAKLAK)2 sequence, composed of D-amino acids for protease resistance, then disrupts mitochondrial membranes in the endothelial cells, triggering apoptosis through cytochrome c release and caspase activation.

Without functional blood supply, downstream adipose tissue undergoes ischemic necrosis. The dead adipocytes are cleared by infiltrating macrophages over the following 2-4 weeks. This mechanism produces permanent fat loss because the fat cells themselves are destroyed, not merely emptied of lipid content (as occurs with diet, exercise, or GLP-1 agonists, where adipocytes shrink but remain viable and can refill).

The landmark preclinical study was published in Science Translational Medicine (2012, DOI: 10.1126/scitranslmed.3002621). Obese rhesus monkeys (a close physiological model to humans) treated with daily subcutaneous adipotide for 28 days lost 11% of total body weight and 39% of abdominal white adipose tissue, as quantified by DEXA and MRI. Body mass index decreased from the obese to normal range. Fasting insulin levels dropped by 50%, indicating dramatic improvement in insulin resistance. The fat loss was selective for white adipose tissue; brown adipose tissue (metabolically beneficial, thermogenic fat) was unaffected, as confirmed by PET-CT imaging of brown fat activity.

Pharmacokinetically, adipotide has a plasma half-life of approximately 30-60 minutes after subcutaneous injection. The D-amino acid pro-apoptotic domain provides resistance to circulating proteases, extending its functional duration. The targeting peptide must reach adipose vasculature while the pro-apoptotic domain remains intact, so the chimeric design balances stability with tissue specificity. Renal effects were observed in the primate study (transient increases in creatinine and BUN), likely due to prohibitin expression on renal proximal tubule cells, which was the primary dose-limiting observation.

For storage, adipotide should be stored as lyophilized powder at -20C. Reconstitute with bacteriostatic water or sterile 0.9% saline. Reconstituted solutions should be kept at 2-8C and used within 14 days. The D-amino acid domain provides good solution stability, but the disulfide bond in the targeting peptide (CKGGRAKDC contains a cysteine) requires protection from reducing agents. Avoid alkaline pH (>8).

Safety observations from the primate study noted reversible renal changes (elevated creatinine, mild proteinuria) that resolved after treatment cessation. These effects are attributed to prohibitin expression in renal tubular epithelium and represent the primary safety consideration. No hepatotoxicity, cardiac toxicity, or bone marrow suppression was observed. The primate study used daily dosing; modified protocols with less frequent dosing or lower doses may mitigate renal effects while preserving fat-loss efficacy. Adipotide has not entered human clinical trials as of the current literature.

This compound represents a fundamentally different approach to fat loss compared to metabolic modulators (AICAR, MOTS-c) or hormone fragments (HGH Fragment 176-191). Rather than altering metabolic pathways to increase fat burning, adipotide physically destroys the vascular infrastructure of fat deposits.