ATX-304 (Formerly O304):
What the Evidence Shows

ATX-304—called O304 or O-304 in earlier papers—is an investigational oral small molecule. It is not a peptide, and it is not an approved treatment. Researchers are studying it because it appears to increase activity across multiple AMPK complexes while also changing aspects of mitochondrial metabolism. Readers new to the distinction between peptide compounds and adjacent research molecules can begin with our guide to what peptides are and how to evaluate the evidence.

The preclinical program is broad, spanning glucose regulation, exercise capacity, kidney injury, and fatty-liver models. Human data are much smaller. A 2018 study in people with type 2 diabetes produced some encouraging secondary and post hoc signals, but its prespecified fasting-glucose comparison was not statistically significant. A small 2026 phase 1b study added preliminary metabolic findings, yet it remains conference-level evidence rather than proof of clinical efficacy.

The same compound appears under two main names. The original scientific literature uses O304 or O-304; its later development name is ATX-304. Searching both names is necessary to see the full research record.

Although it is discussed in peptide-focused communities, ATX-304 is a synthetic, orally studied small molecule rather than an amino-acid chain. Its development program focuses on cardiometabolic conditions, including obesity and related metabolic dysfunction. Company descriptions call it peripherally restricted, meaning it is intended to act outside the central nervous system.

AMP-activated protein kinase, or AMPK, is a cellular energy sensor. When energy availability changes, AMPK helps coordinate processes such as glucose uptake, fatty-acid oxidation, mitochondrial function, and energy-consuming biosynthesis. It is not one switch with one outcome: AMPK exists as multiple α, β, and γ subunit combinations, and its effects depend on tissue, timing, and physiological context.

That complexity helps explain the appeal of a “pan-AMPK” activator, but it also argues against reducing the story to a simple metabolism-on button. Broad pathway activation may produce different effects across organs, and findings in cultured cells or mice cannot be assumed to translate directly to people.

AMPK activity depends heavily on phosphorylation at threonine 172 on its α subunit. The original 2018 work found that O304 made this activated state more resistant to PP2C-mediated dephosphorylation. The compound did not appear to work like a classic AdAM-site allosteric activator, and it did not directly inhibit the phosphatase itself.

This matters because ATX-304 does not create phosphorylation from nothing. Its effect depends on an existing upstream signal that has already activated AMPK. The precise binding interaction remains unresolved, so descriptions of the mechanism should be treated as a working model rather than a complete map.

Later research also points to a mitochondrial component. Cell and animal studies have reported altered oxygen consumption, membrane potential, oxidative stress, and fuel handling. Whether that mitochondrial activity is fully separate from the AMPK effect—and how both arms behave at clinically relevant exposure—remains an active research question.

TELLUS: 28 days in type 2 diabetes

The 2018 TELLUS study randomized 65 adults with type 2 diabetes who were already taking metformin to O304 or placebo. Participants received a once-daily oral suspension for 28 days. The published paper described improvements in insulin-resistance measures, blood pressure, and microvascular perfusion, with a fasting-glucose signal in a subgroup.

Phase 1b: obesity and prediabetes

A 2026 conference abstract described 23 adults with obesity and prediabetes randomized 2:1 to ATX-304 or placebo for eight weeks, with an optional open-label extension. Reported signals included changes in adiponectin, triglycerides, liver fat, visceral fat, and resting metabolic rate. The investigators described the treatment as generally well tolerated in this small study.

Those findings are worth following, but the study was small, short, and available as a conference abstract rather than a full peer-reviewed clinical report. It does not establish durable weight loss, long-term safety, or comparative effectiveness. Larger phase 2 studies are needed.

The 2018 human study used an oral suspension. Later clinical work has involved a sodium-salt tablet formulation. Those formulations should not be treated as automatically interchangeable with each other—or with an unverified powder sold through retail channels.

Form can influence solubility, absorption, exposure, and the relationship between mass and active compound. A purity percentage alone does not establish salt form, clinical equivalence, or bioavailability. Without verified identity, formulation, and pharmacokinetic data, comparisons to clinical dosing are unreliable.

ATX-304 has a more substantial research trail than many compounds circulating in online discussion. Its mechanism is scientifically interesting, its preclinical program spans several metabolic systems, and early human studies provide reasons to continue development. The same record also demands restraint: the human sample is small, the first trial missed its prespecified fasting-glucose comparison, and the most ambitious claims still depend on animal models or preliminary conference data.

The responsible conclusion is neither dismissal nor hype. ATX-304 is an investigational small molecule with credible translational potential and major unanswered questions. Phase 2 results—not vendor descriptions—should determine whether that potential becomes a clinically meaningful finding.