Voxelotor (GBT440)

Catalog No.S8540 Synonyms: GTx011

For research use only.

Voxelotor (GBT440, GTx011) is a novel small molecule hemoglobin modifier which increases hemoglobin oxygen affinity.

Voxelotor (GBT440) Chemical Structure

CAS No. 1446321-46-5

Purity & Quality Control

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Biological Activity

Description Voxelotor (GBT440, GTx011) is a novel small molecule hemoglobin modifier which increases hemoglobin oxygen affinity.
In vitro

GBT440 is a new potent allosteric effector of sickle cell hemoglobin that increases the affinity of hemoglobin for oxygen and consequently inhibits its polymerization when subjected to hypoxic conditions. GBT440 inhibits these isozymes(CYP 1A2, 2C8, 2C9, 2C19, 2D6, and 3A4) with IC50 ranging from 7.9 to 148 μM. It is not a substrate for either P-gp or BCRP transporters[1]. It binds to the N-terminal a chain of Hb[2].

In vivo GBT440 has favorable oral bioavailability of 60, 37, and 36% in rats, dogs, and monkeys, respectively, with similar blood and plasma half-lives of approximately 20 h each. T1/2 value of GBT440 in all animal species is significantly shorter than the T1/2 of red blood cells (∼20 days), which supports that binding of GBT440 to hemoglobin is a reversible process. GBT440 is currently in Phase 3 clinical trials (NCT03036813) in SCD patients[1]. GBT440 increases haemoglobin oxygen affinity, reduces sickling and prolongs RBC half-life in a murine model of sickle cell disease. In a murine model of SCD, GBT440 extends the half-life of RBCs, reduces reticulocyte counts and prevents ex vivo RBC sickling. Importantly, oral dosing of GBT440 in animals demonstrates suitability for once daily dosing in humans and a highly selective partitioning into RBCs, which is a key therapeutic safety attribute. GBT440 shows dose proportional PK, a terminal half-life of 1.5-3 d[2].

Protocol (from reference)

Cell Research:


  • Cell lines: sickle RBCs
  • Concentrations: 0, 300, 600, 1000 μM
  • Incubation Time: 1 h
  • Method:

    whole blood (20% Hct) from SCD patients who has been transfusion free for 2 to 3 months (HbS > 70%) is incubated with various concentrations of GBT440 for 1 h at 37°C, diluted 100-fold in TES/saline buffer and deoxygenated in a Hemox Analyser

Animal Research:


  • Animal Models: Sprague-Dawley rats
  • Dosages: 7.2 to 120 mg/kg
  • Administration: oral administration

Solubility (25°C)

In vitro

Chemical Information

Molecular Weight 337.37


CAS No. 1446321-46-5
Storage 3 years -20°C powder
2 years -80°C in solvent
Smiles CC(C)N1C(=CC=N1)C2=C(C=CC=N2)COC3=CC=CC(=C3C=O)O

In vivo Formulation Calculator (Clear solution)

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Method for preparing in vivo formulation: Take μL DMSO master liquid, next addμL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O, mix and clarify.

Method for preparing in vivo formulation: Take μL DMSO master liquid, next add μL Corn oil, mix and clarify.

Note: 1. Please make sure the liquid is clear before adding the next solvent.
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Molarity Calculator

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Clinical Trial Information

NCT Number Recruitment Interventions Conditions Sponsor/Collaborators Start Date Phases
NCT04335721 Recruiting Drug: Voxelotor Sickle Cell Disease|Sickle Cell Nephropathy University of Illinois at Chicago|Global Blood Therapeutics March 16 2021 Phase 1|Phase 2
NCT03114540 Completed Drug: GBT440 Hepatic Impairment Global Blood Therapeutics March 17 2017 Phase 1
NCT03161015 Completed Drug: GBT440 Renal Impairment Global Blood Therapeutics November 2016 Phase 1
NCT02989168 Terminated Drug: GBT440 Idiopathic Pulmonary Fibrosis|Hypoxemia Global Blood Therapeutics November 2016 Phase 2
NCT03041909 Completed Drug: GBT440 Sickle Cell Disease Global Blood Therapeutics August 2016 Phase 2
NCT02846324 Completed Drug: GBT440|Drug: Placebo Idiopathic Pulmonary Fibrosis|Hypoxemia Global Blood Therapeutics June 2016 Phase 2

(data from https://clinicaltrials.gov, updated on 2022-01-17)

Tech Support

Answers to questions you may have can be found in the inhibitor handling instructions. Topics include how to prepare stock solutions, how to store inhibitors, and issues that need special attention for cell-based assays and animal experiments.

Handling Instructions

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