Research in plain language

AOD-9604

What it is

AOD-9604 is a synthetic, stabilized fragment of the C-terminus of human growth hormone (Tyr-hGH 177-191, also called the "lipolytic domain"), engineered to copy growth hormone's fat-burning effect without raising IGF-1, growth-promoting, or pro-diabetic activity. It has been studied mainly as an anti-obesity agent (stimulating fat breakdown / lipolysis) and, more recently and on a much smaller scale, as a joint-cartilage repair injection. Important honesty up front: the largest human obesity trials, including the pivotal 24-week Phase 2b study, did NOT show clinically meaningful weight loss versus placebo, and the drug program was discontinued.

How studies used it

Model: Rat (obese Zucker rats)
Studied for: Obesity / lipolysis and body-weight gain
Dose: 0.5 mg/kg/day (published as 500 micrograms/kg body weight per day)
Dosing: Once daily
Route: Oral
Duration: 19 days

Effects measured: Body-weight gain was reduced by over 50 percent versus control (15.8 +/- 0.6 g gained vs 35.6 +/- 0.8 g in controls). Adipose tissue showed increased lipolytic activity. Euglycemic clamp testing showed no adverse effect on insulin sensitivity.

Side effects: No adverse effects reported in this study; specifically no impairment of insulin sensitivity

Sources: Ng FM, Sun J, Sharma L, Libinaka R, Jiang WJ, Gianello R. Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone. Horm Res. 2000;53(6):274-8.

Model: Mouse (genetically obese ob/ob and lean C57BL/6J)
Studied for: Obesity: body weight, fat oxidation and lipolysis
Dose: Per-kg dose not stated in the abstract; delivered continuously by implanted mini-osmotic pump over the treatment period. Population: obese ob/ob mice and lean controls.
Dosing: Continuous infusion via mini-osmotic pump
Route: Subcutaneous (implanted osmotic pump)
Duration: 14 days

Effects measured: AOD9604 significantly reduced body-weight gain in obese mice. This was accompanied by increased in vivo fat oxidation and increased plasma glycerol levels (a marker of lipolysis). Unlike full-length hGH, AOD9604 did not cause hyperglycemia or reduce insulin secretion. The abstract reports directional findings without per-group numeric values.

Side effects: No adverse events reported in this study; notably no hyperglycemia and no drop in insulin secretion (in contrast to hGH)

Sources: Heffernan MA, Thorburn AW, Fam B, Summers R, Conway-Campbell B, Waters MJ, Ng FM. Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment. Int J Obes Relat Metab Disord. 2001;25(10):1442-9.

Model: Mouse (obese mice and beta-3 adrenergic receptor knockout mice)
Studied for: Mechanism of lipid metabolism: role of the beta-3 adrenergic receptor
Dose: Per-kg dose not stated in the abstract. Population: obese mice plus beta(3)-adrenergic receptor knockout mice used to probe the mechanism.
Dosing: Daily injection (chronic dosing)
Route: Intraperitoneal
Duration: 14 days

Effects measured: AOD9604 reduced body weight and body fat in obese mice and increased beta(3)-adrenergic receptor (beta3-AR) RNA expression. In beta3-AR knockout mice the chronic weight-loss and increased-lipolysis effects were lost, indicating the chronic effect works through the beta3-AR pathway. Acute energy expenditure and fat oxidation could still rise in knockouts. Abstract gives qualitative directions, not per-group numbers.

Side effects: No adverse events reported in this study

Sources: Heffernan M, Summers RJ, Thorburn A, Ogru E, Gianello R, Jiang WJ, Ng FM. The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta(3)-AR knock-out mice. Endocrinology. 2001;142(12):5182-9.

Model: Rabbit (New Zealand white, n=32; collagenase-induced knee osteoarthritis)
Studied for: Knee osteoarthritis / cartilage repair
Dose: 0.25 mg per knee per injection (absolute per-joint dose; body-weight-normalized dose not reported)
Dosing: Weekly intra-articular injection, with or without hyaluronic acid, for several weeks
Route: Intra-articular injection (ultrasound-guided)
Duration: Treatment over roughly 4 to 7 weeks; assessment at 8 weeks after OA induction

Effects measured: Gross morphological and histopathological cartilage-damage scores were significantly worse in the saline group than in the AOD9604, hyaluronic acid, and AOD9604+hyaluronic acid groups. The AOD9604 plus hyaluronic acid combination gave the best (lowest) damage scores and the shortest lameness period, indicating enhanced cartilage regeneration versus saline.

Side effects: No adverse events reported in this study

Sources: Kwon DR, Park GY. Effect of Intra-articular Injection of AOD9604 with or without Hyaluronic Acid in Rabbit Osteoarthritis Model. Ann Clin Lab Sci. 2015 Summer;45(4):426-32.

Model: In vitro (human serum and urine incubations; mass spectrometry)
Studied for: Anti-doping detection and metabolic stability (AOD9604 is banned by WADA)
Dose: In vitro analytical study; AOD9604 spiked into serum/urine. Reported assay limit of detection 50 pg/mL in urine (not a per-kg therapeutic dose).
Dosing: Single in vitro incubation, not a dosing regimen
Route: In vitro
Duration: Laboratory incubation (not an in vivo duration)

Effects measured: Six candidate metabolites were identified. One metabolite (peptide sequence CRSVEGSCG) was significantly more stable than the parent peptide or other metabolites, making it a useful marker to extend the detection window for doping control. Established a solid-phase extraction method with a 50 pg/mL urine detection limit.

Side effects: Not applicable (in vitro analytical study; no living subjects)

Sources: Cox HD, Smeal SJ, Hughes CM, Cox JE, Eichner D. Detection and in vitro metabolism of AOD9604. Drug Test Anal. 2015;7(1):31-8.

How solid the evidence is

Evidence quality is mixed and the human efficacy data are negative. The strongest WEIGHT-LOSS evidence is in rodents only (Ng 2000 obese Zucker rats; Heffernan 2001 x2 obese/knockout mice) and is roughly 25 years old, with the mouse abstracts giving only directional results, not per-group numbers, and not stating the per-kg dose (only the Zucker rat oral study has a clean published dose of 0.5 mg/kg/day). All three rodent studies share an overlapping Australian author group (Ng and colleagues, the team behind the commercial program), so they are not independent replications. Human evidence is the key honesty point. AOD-9604 was taken through six company-funded trials by Metabolic Pharmaceuticals (about 900 subjects total). The pivotal trial was a 24-week, randomized, double-blind, placebo-controlled Phase 2b study in 502 obese adults (METAOD006; oral 0.25, 0.5 or 1 mg/day). It did NOT produce clinically meaningful weight loss versus placebo, and a 12-week Phase 2b in 300 subjects (METAOD005; 1 to 30 mg/day) likewise failed to deliver a robust, significant fat-loss effect, after which development was discontinued (around 2007). An earlier company press summary highlighted a 1 mg group losing about 2.6 to 2.8 kg vs about 0.8 kg on placebo over 12 weeks, but this did not hold up as a clinically significant result in the larger/longer pivotal trial. CRITICAL CAVEAT: these human trials are NOT indexed in PubMed (published as conference material and in the non-indexed Journal of Endocrinology and Metabolism, Stier et al. 2013, sponsor-affiliated authors), so they could not be cited here with a verified PMID. The Stier paper itself was a SAFETY summary, not an efficacy paper, and reported AOD-9604 as well tolerated with no IGF-1 rise, no glucose/insulin worsening, and no anti-drug antibodies; the doping/detection literature is in vitro only. The osteoarthritis evidence is a single small rabbit study (n=32) and does not address weight loss at all. Bottom line: human anti-obesity efficacy is essentially negative, the positive signals are animal/in-vitro and largely from one sponsor-linked group, and AOD-9604 is a WADA-banned substance.

Sources

Study data, research use only. No established human dosing protocol.