ATX-304

An investigational small molecule

ATX-304 is a synthetic small molecule, taken orally in the clinical program. It affects AMPK-related energy pathways and mitochondrial function. Its precise binding target is unresolved.^1421,1422

Formulations

The older TELLUS study used an O304 suspension. Later studies used sodium-salt capsules or tablets with different absorption. The shared compound name does not identify whether two products share an exposure profile.^1419,1423

The human results

No clear difference

TELLUS randomized 65 adults with type 2 diabetes. The registered main fasting-glucose comparison was not statistically significant, with P=.356.¹⁴¹⁹

Where the positive result came from

The paper reports a smaller, post-hoc subgroup: 25 treated participants and 24 receiving placebo. Fasting glucose changed by -0.60 versus -0.10 mmol/L, with a between-group P=.010. That finding deserves follow-up alongside the full trial result.^1424,1419

The 2026 phase 1b study

Twenty-three adults with obesity and prediabetes received ATX-304 or placebo for eight weeks. Fifteen received the study drug and eight received placebo; all completed treatment. Twelve continued into an eight-week open-label extension. The report is a conference poster.¹⁴²⁰

The 8% metabolism claim

The company reported an 8% rise in resting metabolic rate. The poster marks significance against baseline, includes increases in the placebo group and provides no numerical between-group effect. Its exact bar means are not printed.^1425,1420

Exposure and safety

98.8 hours

The 2026 human poster reports a mean plasma half-life of 98.8 hours, with a standard deviation of 21.8 hours. It estimates about 21 days to steady state.¹⁴²⁰

Gastrointestinal events

In the eight-week blinded phase, diarrhea affected 8/15 treated participants and 2/8 receiving placebo; vomiting affected 4/15 and 0/8. The poster describes clustering during a fructose challenge used for a metabolic measurement.¹⁴²⁰

Mild and serious events

One event of flatulence was mild in intensity but classified as serious because it required overnight hospitalization. The investigator considered it treatment-related. It resolved within 6.25 hours.¹⁴²⁰

Product-specific exposure

Two patent examples studied sodium-salt capsules in 24 healthy adults and tablets in 20. The tablet strengths were 212.12 and 424.24 mg of salt, equivalent to 200 and 400 mg of parent compound. These are study formulations and amounts.¹⁴²³

Animal studies

Liver findings varied within the organ

In a mouse model of fatty liver disease, ATX-304 reduced liver fat and improved fibrosis in the left lobe. Fibrosis scores rose in the right median lobe. The same study recorded higher blood bile acids and urea nitrogen.¹⁴²⁶

Exercise and longevity claims

An aging-mouse study reported better exercise capacity and cardiac measures. A separate experiment extended lifespan in worms. Human trials have yet to establish improved exercise performance or longer life.^1427,1428

The semaglutide combination

A conference experiment tested ATX-304 with semaglutide in obese mice, with eight animals per group. It reported more weight loss during combination treatment and less regain after semaglutide withdrawal. Human combination results remain unavailable.¹⁴²⁹

Common questions

01 What is ATX-304?

ATX-304 is an experimental oral drug, previously called O304. It affects pathways involved in how cells use energy. Researchers have tested several formulations, including newer sodium-salt tablets.^{1421,1423,1430,1422}

02 Is ATX-304 a peptide?

No. ATX-304 is a synthetic small molecule and has no peptide sequence. Reptides includes some non-peptide research compounds.¹⁴²¹

03 Are ATX-304 and O304 the same compound?

Yes. ATX-304 is the newer name used for O304. The early suspension and later sodium-salt tablets have different absorption, so study results need to be read with the formulation in mind.^{1424,1431,1430,1423}

04 Is OS-01 another name for ATX-304?

OS-01 has not been confirmed as another name for ATX-304 in the cited chemical records or developer material. An autocomplete suggestion is the only link found between the names.^1421,1430

05 Is ATX-304 an approved medicine or supplement?

ATX-304 remains investigational. The FDA approval and label searches found no matching product, and the developer describes access through clinical trials. A retail listing is not an approval record and cannot by itself show that its product matches the study drug.^{1432,1433,1420,1434}

06 What can public user reports about products sold as ATX-304 tell us?

Personal accounts report experiences without confirming what a product contains or whether the drug caused an effect. The human trials used specifically manufactured suspensions, capsules or sodium-salt tablets. Linking a retail product to those results requires evidence about its identity, formulation and contents.^1423,1420

07 Is ATX-304 prohibited in sport?

The 2026 WADA list prohibits AMPK activators at all times under class S4.4.1. ATX-304 is not printed as a named example, so applying that class to it is a mechanism-based interpretation. The 2027 list retains the class and takes effect on January 1, 2027.^1435,1436

08 What human studies of ATX-304 or O304 have been identified?

The evidence includes an early dose-escalation safety summary, the 65-person TELLUS diabetes trial, two human drug-exposure studies disclosed in a patent, and a 23-person obesity and prediabetes study reported in 2026. A separate multiple-ascending-dose trial is registered in CTIS. TELLUS and the 2026 poster supply the main published human treatment findings.^{1424,1419,1423,1420,1434}

09 What did the TELLUS trial test?

TELLUS randomized 65 adults with type 2 diabetes who were taking stable metformin treatment. The O304 group received a 1,000 mg oral suspension once daily for 28 days; the other group received matching placebo. Thirty-three were assigned O304, 32 placebo, and 59 completed the study.^1419,1424

10 Did TELLUS meet its main glucose endpoint?

No statistically significant difference was found in the registered primary fasting-glucose analysis of all 65 randomized participants. The reported P value was 0.356.¹⁴¹⁹

11 Why did the TELLUS paper report a positive glucose result?

The paper focused on a smaller group selected after the trial by their starting fasting glucose. In that subgroup, glucose changed by -0.60 mmol/L in 25 O304 participants and -0.10 mmol/L in 24 placebo participants, with P=.010. The full trial and subgroup therefore give different answers: the main comparison was null, while the later subgroup analysis was positive.^{1424,1419,1437}

12 Did TELLUS report any other human signals?

The paper reported blood-pressure reductions and changes in calf microvascular perfusion. Among 30 O304 and 27 placebo participants, systolic pressure changed by -5.8 versus +1.2 mmHg, and diastolic pressure by -3.8 versus +0.9 mmHg. These were short-term findings from a trial with several outcomes and post-hoc analyses.¹⁴²⁴

13 What did the 2026 phase 1b study look like?

The study randomized 23 adults with obesity and prediabetes to oral ATX-304 400 mg once daily or placebo for eight weeks. Fifteen received ATX-304 and eight received placebo, and all completed that period. Twelve completed an optional eight-week extension in which everyone received ATX-304.¹⁴²⁰

14 What effects did the 2026 phase 1b poster report?

The poster reported changes from baseline in adiponectin, triglycerides, liver fat, visceral fat, and resting metabolic rate. It called weight loss minimal and reported no effect on mixed-meal glucose measures, an insulin-sensitivity index, or leptin. Several figures show tests against baseline rather than a numerical treatment-versus-placebo effect.¹⁴²⁰

15 Has ATX-304 been proven to cause weight loss in people?

A meaningful weight-loss benefit in people is still unproven. The 2026 phase 1b poster describes weight loss as minimal and gives no numerical treatment-versus-placebo estimate. Larger weight-management studies were planned at the time of the sponsor report.^{1424,1420,1425}

16 Did ATX-304 increase resting metabolic rate by 8 percent?

The 8% figure comes from a company release. It is not identified there as an average or as the effect after subtracting placebo. The poster shows both groups, with a significance marker against baseline; it does not print exact group means or a numerical between-group difference.^1425,1420

17 What doses and formulations have been studied in people?

Early oral dose-escalation studies reported 100 to 2,400 mg, with duration and formulation details missing from the available summary. TELLUS used a 1,000 mg oral suspension daily for 28 days. Patent studies used oral sodium-salt capsules at 200, 400 or 800 mg through 25 days, and oral tablets at 212.12 or 424.24 mg salt daily for 21 days. Those tablet amounts equal 200 or 400 mg of parent compound. The 2026 phase 1b study used oral 400 mg daily for eight weeks. These describe study exposures.^{1424,1419,1423,1420}

18 Are the suspension, capsules, and tablets equivalent?

Their exposure differs. The patent compares the newer sodium-salt products with the older suspension and reports different blood drug levels. Printed milligram amounts can also refer either to the salt or to its parent-compound equivalent.^1423,1424

19 What do the patent pharmacokinetic examples add?

The patent describes drug absorption in two studies: sodium-salt capsules in 24 healthy adults, and tablets in 20. Some exposure measurements used smaller groups, including nine evaluable participants per tablet arm. The results help explain why the formulations need to be distinguished.¹⁴²³

20 What is the human half-life of ATX-304?

The 2026 poster reports a mean plasma half-life of 98.8 hours, with a standard deviation of 21.8 hours, in adults with obesity and prediabetes. Drug levels reached steady state after about 21 days. The older 11-hour estimate comes from animal data.^1420,1424

21 What safety findings have been reported in human studies?

In TELLUS, nonserious events affected 19 of 33 O304 participants and 23 of 32 placebo participants. Serious events affected zero and one respectively; the placebo event was unrelated renal colic, and there were no deaths. In the 23-person phase 1b study, diarrhea occurred in 8 of 15 ATX-304 participants and 2 of 8 placebo participants, dizziness in 4 of 15 and 1 of 8, and vomiting in 4 of 15 and none.^1419,1420

22 How can an adverse event be mild and serious at the same time?

Severity describes intensity, while seriousness reflects outcomes such as hospitalization. In the phase 1b poster, one mild flatulence event began about eight hours after the last dose, required an overnight hospital stay, was considered treatment-related, and resolved within 6.25 hours. The hospitalization made it serious even though the symptom was mild.¹⁴²⁰

23 What safety questions remain open?

Long-term safety, pregnancy and the full range of drug interactions remain open questions. The controlled treatment studies were small and short. There is too little exposure to estimate rare harms reliably.^1420,1419

24 What is the status of the current ATX-304 trial?

The ATX-304-02 study began in Germany on September 16, 2024. The sponsor halted it on July 11, 2025, with no participant still on treatment and no reported change to the benefit-risk balance. It restarted on August 3, 2026. The registry currently lists it as Authorised, with an estimated end on February 28, 2027 and no posted results.¹⁴³⁴

25 How is ATX-304 thought to work?

ATX-304 affects AMPK signaling and mitochondrial energy handling. Laboratory experiments found increased proton leak in isolated mouse mitochondria while tested human liver cells maintained ATP, their main energy-carrying molecule. The precise molecular binding target is unknown.^1422,1430

26 What did the aged-mouse exercise study show?

Human exercise-performance results are still missing. In aged mice, O304 improved several insulin, cardiac and treadmill measures. Heart weight was 15% higher, with larger heart-muscle cells and higher capillary density; the study detected no additional fibrosis or glycogen accumulation.¹⁴²⁷

27 Has O304 been shown to extend lifespan?

The reported lifespan finding is in C. elegans worms exposed to 100 micromolar O304. The same paper tested cells and isolated rat arteries. Human lifespan has not been measured in the cited clinical studies; the worm paper was available only as an abstract.¹⁴²⁸

28 Has ATX-304 been tested with semaglutide?

The available combination results are from obese mice, with eight animals per group. ATX-304 plus semaglutide produced 27% weight loss by day 15, prompting a semaglutide dose reduction under the animal-use rules. A separate experiment found less regain after semaglutide withdrawal. Human combination results remain unavailable.¹⁴²⁹

29 What did the mouse liver study find?

In a mouse fatty-liver model, ATX-304 reduced fat mass, blood cholesterol, liver triglycerides and oxidized lipids. Fibrosis improved in the left liver lobe but was worse in the right median lobe than in both control groups. Blood bile acids, blood urea nitrogen and liver free cholesterol also increased.¹⁴²⁶

30 How does ATX-304 compare with MOTS-c?

There is no direct clinical comparison in the available evidence. ATX-304 is a synthetic small-molecule drug candidate. Its separate studies cannot establish whether it is more effective or safer than MOTS-c.^{1421,1424,1420}

31 Why do the sources tell different stories about ATX-304?

The official TELLUS registry reports the null main analysis, while the journal paper emphasizes a positive subgroup. The newer human findings come from a sponsor-linked conference poster. Patent records describe formulations and blood drug levels, and company releases give the developer’s account. These sources need to be read together.^{1419,1424,1420,1423,1425}

32 Were the stomach symptoms linked to the drug or to the study procedure?

The poster describes gastrointestinal symptoms clustering during a fructose challenge, a test used to measure metabolism. Some symptoms were more common in the ATX-304 group. The small study cannot separate every contribution from the drug, the challenge and individual susceptibility.¹⁴²⁰

33 How can I check whether a clinical trial is actually recruiting?

Use the trial’s current official record and study contact. Authorised is a regulatory status, and an estimated completion date can change. The ATX-304-02 record documents a restart, but does not by itself confirm that a place is available or that someone meets the eligibility criteria.¹⁴³⁴