ATX-304 — Safety, Research, Risks & Legal Status

Not medical advice. ATX-304 is discussed here for informational and harm-reduction purposes only. We do not endorse use, and any dosing context is informational, not a protocol.

Also known as	O-304; OS-01; CAS 1261289-04-6
Category	Research Chemical
CAS Number	1261289-04-6
Developer	Amplifier Therapeutics (Amplifier TX AB, Sweden) / Cambrian Bio
Development Stage	Phase 2 clinical trials (obesity, cardiometabolic disease, T2D); Phase IIa completed as of 2026
Mechanism Class	Direct pan-AMPK activator (phosphatase 2C inhibition); peripherally restricted
Route of Administration	Oral (small molecule, orally bioavailable)
Key Differentiator	Direct AMPK activation vs. indirect mechanisms (e.g., metformin); no CNS penetration by design
US legal status	Not FDA-approved. Investigational drug in Phase 2 clinical development (obesity, type 2 diabetes, cardiometabolic disease). Outside of approved clinical trials, ATX-304 is available only as a research chemical labeled for in vitro and preclinical use; it is not approved for human therapeutic use or human consumption in the United States or EU. No supplement exemption applies.

What is ATX-304?

ATX-304 (also called O-304) is an orally bioavailable, small-molecule, direct pan-AMPK (AMP-activated protein kinase) activator developed by Amplifier Therapeutics (Amplifier TX AB, Sweden), a subsidiary of Cambrian Bio. It is peripherally restricted with limited CNS penetration and is designed to simultaneously increase cellular glucose and fatty acid uptake while enhancing mitochondrial respiration. It is currently in Phase 2 clinical trials for obesity and cardiometabolic indications.

How it works

ATX-304 directly activates all major AMPK isoforms (alpha-beta1 and alpha-beta2 subunits) by suppressing protein phosphatase 2C-mediated dephosphorylation of pAMPKα-Thr172 - the primary phosphorylation site that keeps AMPK active. Unlike indirect AMPK activators such as metformin, which work by altering AMP:ATP ratios, ATX-304 acts on the phosphatase regulatory step. The net effect described in trial data is a coordinated increase in glucose uptake, fatty acid oxidation, and mitochondrial respiration - framed by the developers as "balancing energy supply and metabolic demand" to elevate systemic metabolic rate. Peripheral restriction reduces CNS-mediated effects and may limit centrally driven adverse events.

Background & history

ATX-304 was discovered by three AMPK researchers - Helena Edlund, Thomas Edlund, and the late Olof Karlsson - at Betagenon AB (Sweden), which was subsequently acquired by Amplifier Therapeutics. Cambrian Bio, backed by Future Ventures and RA Capital Management, provided development funding. The compound was earlier designated O-304 in preclinical and early-phase literature. Phase 1b was completed in adults with obesity or prediabetes (150+ subjects). Phase IIa was completed in type 2 diabetes patients on background metformin (28-day exposure). As of June 2026, positive translational data were presented at the American Diabetes Association 86th Scientific Sessions.

What the research says

ATX-304 has human clinical trial data, which is uncommon for compounds in this class. Phase 1b (obesity/prediabetes): statistically significant reductions in liver fat and visceral adipose tissue, improved triglycerides, elevated adiponectin, increased resting metabolic rate, and weight loss without documented caloric restriction. Improved peripheral microvascular perfusion was also reported. Phase IIa (type 2 diabetes on metformin): fasting plasma glucose reduction of -0.60 mM (p=0.0096), improved HOMA-IR (a surrogate for insulin resistance), blood pressure reduction, and tolerability comparable to placebo. Preclinical (animal) data include muscle-sparing weight loss, reversal of metabolic abnormalities, improved exercise endurance, hepatoprotective effects in metabolic-associated fatty liver disease (MASLD), and protection against cisplatin-induced acute kidney injury. These are early-phase and preclinical signals; long-term efficacy and safety data in humans are not yet available, and no regulatory approval exists for any indication.

Reported effects

Direct pan-AMPK activation across alpha-beta1 and alpha-beta2 isoforms (human and preclinical data)
Reduction in fasting plasma glucose and improved insulin sensitivity in Phase IIa T2D cohort
Reduction in liver fat and visceral adipose tissue in Phase 1b (obesity/prediabetes)
Increased resting metabolic rate and weight loss without documented caloric reduction (Phase 1b)
Improved peripheral microvascular perfusion (Phase 1b)
Muscle-sparing weight loss and hepatoprotective effects in preclinical models
Protection against cisplatin-induced acute kidney injury in animal models (preclinical only)

Dosing & administration (informational)

Human trial doses are not publicly detailed in available literature; the Phase 1b and Phase IIa protocols are proprietary to Amplifier Therapeutics/Cambrian Bio. Published data describe multiple oral dosing regimens over 4-week periods without specifying mg amounts in accessible summaries. This entry does not provide dosing guidance. Anyone considering clinical use should consult a licensed clinician and refer only to enrolled clinical trial protocols.

This is general research/context information, not medical advice or a recommended protocol.

Safety & side effects

No serious adverse events attributed to ATX-304 in Phase 1b or Phase IIa trials (up to 4-week exposure)
Treatment-emergent adverse events predominantly mild and occurring at placebo-comparable frequency
GI symptoms (primarily mild nausea) most common and reported as self-resolving
No hypoglycemic episodes reported in diabetic cohorts on background metformin
No evidence of mitochondrial dysfunction; no elevation in core body temperature or resting heart rate
Theoretical hypoglycemia risk when combined with other glucose-lowering agents - not yet formally characterized in longer trials
Long-term safety data beyond 4 weeks in humans is not yet available

Drug & supplement interactions

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Who should avoid it

Human self-administration outside an approved clinical trial - this is an investigational drug without established safety beyond 4-week exposure
Combination with insulin or sulfonylureas without medical supervision given theoretical hypoglycemia risk
Assuming research chemical vendor sourcing is equivalent to clinical-trial-grade material
Treating Phase 1b/IIa signals as established therapeutic efficacy - these are early-phase findings

How it is commonly combined

No human evidence supports or characterizes any combination regimen outside of clinical trial protocols. Preclinical data on ATX-304 plus semaglutide exist (ENDO 2025 abstract) but human translation is unknown. Combining investigational AMPK activators with approved glucose-lowering agents carries uncharacterized interaction risk.

Legal & regulatory. Not FDA-approved. Investigational drug in Phase 2 clinical development (obesity, type 2 diabetes, cardiometabolic disease). Outside of approved clinical trials, ATX-304 is available only as a research chemical labeled for in vitro and preclinical use; it is not approved for human therapeutic use or human consumption in the United States or EU. No supplement exemption applies.

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Frequently asked questions

What dose of ATX-304 should I take?

This entry does not provide dosing guidance. ATX-304 is an investigational drug without regulatory approval. Specific doses used in clinical trials are not publicly detailed in available literature, and self-administration outside an approved trial carries unknown risk. Consult a licensed clinician.

How does ATX-304 differ from metformin?

Metformin activates AMPK indirectly by inhibiting mitochondrial complex I, which raises the AMP:ATP ratio and secondarily triggers AMPK. ATX-304 directly suppresses a phosphatase (PP2C) that would otherwise deactivate AMPK, meaning it does not depend on altering the cell's energy charge. It also activates all AMPK isoforms (pan-AMPK) and is peripherally restricted.

Is ATX-304 the same as O-304?

Yes. O-304 is an earlier designation for the same compound (CAS 1261289-04-6) used in preclinical and earlier-phase publications. ATX-304 is the current clinical development name used by Amplifier Therapeutics and Cambrian Bio.

Has ATX-304 been tested in humans?

Yes, though only in early-phase trials. A Phase 1b study enrolled 150+ adults with obesity or prediabetes and a Phase IIa study enrolled type 2 diabetes patients on metformin for 28-day exposure. Both reported positive metabolic signals and no serious adverse events. These are small, short-duration studies; long-term safety and efficacy are not established.

Can I legally purchase and use ATX-304?

In the United States, ATX-304 is an unapproved investigational drug. It is sold by research chemical suppliers for in vitro use only. Purchase for personal human use does not have regulatory sanction. It is not a supplement and has no FDA approval for any indication.

What indications is ATX-304 being developed for?

Current clinical development focuses on obesity, type 2 diabetes, and cardiometabolic disease. Preclinical data also suggest potential in metabolic-associated fatty liver disease (MASLD) and acute kidney injury protection, but these have not advanced to human trials based on available information.

References & further reading

PubMed: "AMPK activator ATX-304 cisplatin acute kidney injury" - https://pubmed.ncbi.nlm.nih.gov/38749175/
PubMed: "AMPK-activator ATX-304 MASLD oxidative stress metabolic switching" - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11981618/
ResearchGate: "PAN-AMPK activator O304 improves glucose homeostasis and microvascular perfusion in mice and type 2 diabetes patients" - https://www.researchgate.net/publication/325906299
Cambrian Bio press release (ADA 2026 Phase 1b data): https://www.cambrianbio.com/news-and-publications/cambrian-bio-presents-positive-human-translational-data-for-atx-304-the-first-ampk-network-activator-at-the-american-diabetes-associations-86th-scientific-sessions
ClinicalTrials.gov: search terms "ATX-304" or "O-304 AMPK activator obesity type 2 diabetes"