Sobetirome (GC-1)

Overview

Sobetirome (GC-1) is a non-peptide small-molecule thyromimetic that selectively activates thyroid hormone receptor beta (TRβ) over TRα, designed to lower cholesterol and triglycerides without the cardiac effects of natural thyroid hormone. It completed Phase 1 trials in healthy volunteers for dyslipidemia (discontinued), but has no FDA or EMA approval and no validated human dose for any indication. Planned human trials in X-linked adrenoleukodystrophy were withdrawn before enrollment; all neurological data are preclinical only.

Mechanism of Action

Sobetirome acts as an agonist at thyroid hormone receptor beta (TRβ) with substantially reduced affinity for TRα, conferring tissue-selective thyromimetic activity. Structural features—an oxyacetic acid moiety and absence of the amino group found in T3—underlie its subtype selectivity in both binding and activation. In hypothyroid mice, this TRβ selectivity produced lipid-lowering effects comparable to T3 without the cardiac chronotropic (heart-rate) increase driven by TRα, supporting the design goal of metabolic benefit with reduced cardiac risk.

Research Summary

Human data are limited to Phase 1 trials in healthy volunteers conducted by QuatRx Pharmaceuticals; company press releases (not peer-reviewed) reported LDL-C reductions up to 22% (single-ascending-dose, 1–450 mcg) and 41% (multiple-ascending-dose, 10–100 mcg/day × 14 days) with no significant heart-rate or TSH change. Development for dyslipidemia was discontinued and no Phase 2/3 data exist. Two planned human trials in X-linked adrenoleukodystrophy (NCT01787578, NCT03196765) were withdrawn before enrolling any participants; zero human neurological efficacy data exist. In Abcd1 knockout mice (X-ALD model), intraperitoneal dosing (0.1–1.0 mg/kg/day, 7–28 days) lowered serum and tissue very-long-chain fatty acid (VLCFA) levels; chronic oral dosing (0.4–2.0 mg/kg, 11–18 weeks) modestly reduced brain C26 VLCFA by 13–24% after 12 weeks, though the higher dose caused up to 20% body-weight loss requiring early termination. In experimental autoimmune encephalomyelitis mice, sobetirome reduced clinical disease severity, axonal degeneration, and oligodendrocyte loss versus vehicle controls.

Vendors selling Sobetirome (GC-1)

Scored vendors carrying Sobetirome (GC-1), ranked by trust grade. Grades are computed from indexed Certificates of Analysis. Full $/mg pricing is on the comparison page.

Reported Side Effects

• Significant weight loss (up to 20%) at higher chronic doses in mice, requiring early termination
• Theoretical thyrotoxicosis-like effects (class risk; TRβ selectivity designed to reduce cardiac/TRα-mediated effects)
• No human long-term safety data exist to confirm tolerability
• Zero human efficacy data in neurological indications; both ALD trials withdrawn without enrollment
• Unregulated gray-market products; purity/identity cannot be assumed without independent verification

Compare Sobetirome (GC-1) with Others

Research References

• PubChem Compound Summary for CID 9862248, Sobetirome.
• A high-affinity subtype-selective agonist ligand for the thyroid hormone receptor. 1998. PMID 9653548.
• The thyroid hormone receptor-beta-selective agonist GC-1 differentially affects plasma lipids and cardiac activity. 2000. PMID 10965874.
• Sobetirome: a case history of bench-to-clinic drug discovery and development. 2008. PMID 19002578.

Frequently asked questions

Has Sobetirome (GC-1) been independently lab-tested?

Disclosed Labs has collected 1 Certificate of Analysis (COA) for Sobetirome (GC-1) from 1 independent testing lab. 1 vendor has submitted material for testing. Products average 97.3% tested purity across the corpus. Full testing data is available at https://www.disclosedlabs.com/peptides/sobetirome/testing.

Where can researchers source Sobetirome (GC-1)?

1 vendor with Disclosed Labs trust grades currently list Sobetirome (GC-1), including Kimera Chems. Compare live prices and lab-verified COAs at https://www.disclosedlabs.com/prices/sobetirome.

How does Sobetirome (GC-1) work?

Sobetirome acts as an agonist at thyroid hormone receptor beta (TRβ) with substantially reduced affinity for TRα, conferring tissue-selective thyromimetic activity. Structural features—an oxyacetic acid moiety and absence of the amino group found in T3—underlie its subtype selectivity in both binding and activation. In hypothyroid mice, this TRβ selectivity produced lipid-lowering effects comparable to T3 without the cardiac chronotropic (heart-rate) increase driven by TRα, supporting the design goal of metabolic benefit with reduced cardiac risk.

What does the research say about Sobetirome (GC-1)?

Human data are limited to Phase 1 trials in healthy volunteers conducted by QuatRx Pharmaceuticals; company press releases (not peer-reviewed) reported LDL-C reductions up to 22% (single-ascending-dose, 1–450 mcg) and 41% (multiple-ascending-dose, 10–100 mcg/day × 14 days) with no significant heart-rate or TSH change. Development for dyslipidemia was discontinued and no Phase 2/3 data exist. Two planned human trials in X-linked adrenoleukodystrophy (NCT01787578, NCT03196765) were withdrawn before enrolling any participants; zero human neurological efficacy data exist. In Abcd1 knockout mice (X-ALD model), intraperitoneal dosing (0.1–1.0 mg/kg/day, 7–28 days) lowered serum and tissue very-long-chain fatty acid (VLCFA) levels; chronic oral dosing (0.4–2.0 mg/kg, 11–18 weeks) modestly reduced brain C26 VLCFA by 13–24% after 12 weeks, though the higher dose caused up to 20% body-weight loss requiring early termination. In experimental autoimmune encephalomyelitis mice, sobetirome reduced clinical disease severity, axonal degeneration, and oligodendrocyte loss versus vehicle controls.