Description
Summary Abstract
ATX-304 (formerly O304; oral small molecule; pan-AMPK activator; MW ~388 g/mol; developed by Amplifier Therapeutics / Cambrian Bio) is a first-in-class, orally bioavailable, peripherally restricted small molecule that directly activates AMP-activated protein kinase (AMPK) across all tissue isoforms while simultaneously enhancing mitochondrial respiration through calibrated uncoupling. Unlike all other known AMPK activators — including indirect activators such as metformin (which generates ATP depletion as its activating signal) and allosteric activators such as PF-793 or MK-8722 (which caused cardiac hypertrophy and glycogen accumulation in preclinical testing) — ATX-304 suppresses dephosphorylation of threonine-172 (pT172) on the AMPKα subunit, stabilizing the active phosphorylated form without requiring a drop in cellular ATP. This mechanism requires the upstream kinase LKB1 and activates only cells with basal AMPK tone, conferring physiological selectivity. ATX-304 is deliberately peripherally restricted (does not cross the blood-brain barrier), avoiding the paradoxical hypothalamic AMPK effect of increasing appetite. Phase IIa proof-of-concept data (TELLUS trial; n=65 T2D patients on metformin; 28 days) demonstrated statistically significant reductions in fasting plasma glucose (−0.60 mM vs. −0.10 mM placebo, p=0.010), diastolic blood pressure reduction, and increased peripheral microvascular perfusion by MRI. Post-hoc renal analyses revealed significant reduction in eGFR (nephroprotective hemodynamic effect). Phase 1B trials in prediabetic, overweight/obese subjects are active as of mid-2026 under Amplifier Therapeutics.
Clinical Indications
ATX-304’s broad cardiometabolic mechanism positions it across multiple therapeutic areas:
- Type 2 Diabetes and Insulin Resistance: TELLUS Phase IIa trial (28 days, T2D on metformin) — statistically significant FPG reduction (−0.60 mM), significant HOMA-IR decrease within treated group; direct beta cell protection via reduced amyloid formation and enhanced autophagy is mechanistically distinct from all approved antidiabetic agents.
- Obesity / Cardiometabolic Disease: Preclinical: −21% fat mass loss in 28 days in DIO mice, entirely fat-derived with no lean mass reduction; ATX-304 + GLP-1 RA combination produced −27% weight loss with preservation of lean mass after GLP-1 discontinuation (ENDO 2025 data).
- MASLD / MASH (Fatty Liver Disease): JCI Insight 2025 study in CD-HFD mice: blood cholesterol normalized (143 vs. 212 mg/dL controls), liver steatosis substantially reduced, fibrosis attenuated; transcriptomic catabolic switch confirmed (↑ACAA1B, EHHADH, ACOX1; ↓ACACA, FASN).
- Diabetic Kidney Disease / Nephroprotection: Phase IIa post-hoc: significant eGFR reduction (hemodynamic nephroprotection), additive to ACEi/ARB therapy; AKI protection in cisplatin model: serum creatinine reduced (0.02 vs. 0.05 mM, p=0.03), NGAL 3× reduced, AMPK-dependent metabolic reprogramming confirmed.
- Post-GLP-1 Weight Maintenance: ENDO 2025 DIO mouse data: ATX-304 prevented weight regain after GLP-1 discontinuation in a dose-dependent manner; highest dose group continued fat loss (−26% vs. baseline) despite GLP-1 RA withdrawal and hyperphagia.
Contraindications
- Active Severe Hypoglycemia Risk States: While ATX-304 improves insulin sensitivity, additive risk with concomitant insulin or sulfonylurea therapy in patients who have not adjusted doses may produce hypoglycemia; glucose monitoring recommended at initiation.
- LKB1-Deficient Tumors / Peutz-Jeghers Syndrome: ATX-304 requires the upstream kinase LKB1 for AMPK activation; LKB1-null tissues (e.g., certain NSCLC, cervical, and pancreatic tumors) may be unresponsive; Peutz-Jeghers patients with germline LKB1 mutations may have altered metabolic responses and tumor biology interactions that require separate evaluation.
- Severe Hepatic Impairment (Child-Pugh C): Phase I pharmacokinetics established in healthy subjects and T2D patients; extensive hepatic disease may alter drug metabolism and create unexpected accumulation; data in Child-Pugh C populations have not been published.
- Pregnancy and Lactation: No reproductive toxicology data published; energy-partitioning alterations from systemic AMPK activation during fetal development or lactation are of unknown safety significance; avoid use.
Mechanism of Action (MOA)
ATX-304 operates through a mechanistically novel multi-pronged strategy to restore cardiometabolic homeostasis:
pT172 Phosphatase Protection — Pan-AMPK Activation
ATX-304 inhibits the dephosphorylation of Threonine-172 (pT172) on the AMPKα catalytic subunit, the critical activating phosphorylation site. Unlike metformin, which activates AMPK indirectly via Complex I inhibition and AMP accumulation (ATP depletion), ATX-304 maintains AMPK in its active state without requiring energetic stress. This requires the upstream kinase LKB1, conferring selectivity to metabolically active tissues with basal AMPK tone. All major AMPK heterotrimers (αβ1γ and αβ2γ isoforms) are activated, producing broad tissue coverage without the cardiac glycogen-loading observed with allosteric β1-specific activators.
Calibrated Mitochondrial Uncoupling
ATX-304 produces mild, graded mitochondrial uncoupling in metabolic tissues — increasing basal oxygen consumption rate (OCR) by approximately 38% in tubular epithelial cells — without the dangerous uncontrolled hyperthermia that limits clinical use of agents such as FCCP or DNP. This uncoupling elevates the AMP:ATP ratio locally, creating a secondary AMPK activation loop and increasing the overall rate of fuel oxidation (fat + glucose) while simultaneously boosting mitochondrial biogenesis through PGC-1α upregulation. The net effect is an exercise-mimetic metabolic state: increased energy expenditure, preferential fat oxidation, and enhanced mitochondrial health.
Peripheral Restriction — No CNS Appetite Activation
A critical pharmacological feature of ATX-304 is its inability to cross the blood-brain barrier (BBB). This is clinically important because hypothalamic AMPK activation is orexigenic — central AMPK stimulation increases appetite and would counteract the compound’s peripheral metabolic benefits. ATX-304’s peripheral restriction avoids this paradox entirely, allowing the skeletal muscle, liver, adipose, kidney, and vascular effects to proceed without compensatory hyperphagia, which distinguishes it favorably from thyroid hormone-based or non-selective mitochondrial uncoupler strategies.
Multi-Tissue Cardiometabolic Reprogramming
Tissue-specific AMPK activation produces a coordinated metabolic shift: in skeletal muscle, insulin-independent GLUT4 translocation improves glucose uptake. In liver, AMPK phosphorylates ACC (acetyl-CoA carboxylase) to suppress de novo lipogenesis and activates CPT1 to enhance fatty acid oxidation, reducing hepatic triglyceride accumulation. In adipose tissue, ATGL-driven lipolysis is enhanced. In vasculature, eNOS activation improves endothelial function and microvascular perfusion. In pancreatic beta cells, AMPK-mediated autophagy reduces islet amyloid polypeptide (IAPP) amyloid deposition and preserves insulin secretory function.
Key Features & Specifications
Key pharmacological and clinical attributes of ATX-304:
Chemical Analysis
| Property | Specification Reference Data |
|---|---|
| Compound Class | Furazano[3,4-b]pyrazine-derived oral small molecule; pan-AMPK activator |
| Common Names / Development Names | ATX-304; formerly O304 (Betagenon AB); Amplifier Therapeutics / Cambrian Bio |
| Molecular Weight (Approx.) | ~388 g/mol (sodium salt form) |
| Solubility | Oral bioavailability confirmed; water-soluble salt formulation |
| BBB Penetration | None (peripherally restricted) |
| Plasma Half-Life | Long; steady state achieved approximately Day 14 (Phase I data) |
| Form / Variation | Capsules (C-052) |
| Quantity | Per capsule count per bottle; see product listing |
Storage, Safety, and Handling
Storage Protocol
Store capsules at room temperature (15–25 °C) in a cool, dry place, away from direct sunlight and humidity. Original packaging is recommended. As an oral small molecule, ATX-304 does not require cold-chain storage, which is a logistical advantage over lyophilized peptide formulations. Avoid exposure to temperatures above 30 °C for prolonged periods.
Handling & Compliance
Standard handling precautions for oral small molecule pharmaceuticals apply. No PPE beyond standard laboratory practices is required. The primary Phase I and IIa safety signal was favorable: no dose-limiting toxicities, no serious AEs in published TELLUS trial data. Additive hypoglycemia risk with insulin or sulfonylurea co-administration warrants glucose monitoring. LKB1 status may influence response in oncology research settings. Regulatory status: Phase IIa completed; IND active; not currently approved by FDA or EMA for any indication.