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  1. Article: GBT440 reverses sickling of sickled red blood cells under hypoxic conditions

    Dufu, Kobina / Oksenberg, Donna

    Hematology reports

    2018  Volume 10, Issue 2, Page(s) 7419

    Abstract: Sickle cell disease is characterized by hemolytic anemia, vasoocclusion and early mortality. Polymerization of hemoglobin S followed by red blood cell sickling and subsequent vascular injury are key events in the pathogenesis of sickle cell disease. ... ...

    Abstract Sickle cell disease is characterized by hemolytic anemia, vasoocclusion and early mortality. Polymerization of hemoglobin S followed by red blood cell sickling and subsequent vascular injury are key events in the pathogenesis of sickle cell disease. Sickled red blood cells are major contributors to the abnormal blood rheology, poor microvascular blood flow and endothelial injury in sickle cell disease. Therefore, an agent that can prevent and or reverse sickling of red blood cells, may provide therapeutic benefit for the treatment of sickle cell disease. We report here that GBT440, an anti-polymerization agent being developed for the chronic treatment of sickle cell disease, increases hemoglobin oxygen affinity and reverses
    Language English
    Publishing date 2018-05-14
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2586645-X
    ISSN 2038-8330 ; 2038-8322
    ISSN (online) 2038-8330
    ISSN 2038-8322
    DOI 10.4081/hr.2018.7419
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  2. Article ; Online: GBT440 improves red blood cell deformability and reduces viscosity of sickle cell blood under deoxygenated conditions.

    Dufu, Kobina / Patel, Mira / Oksenberg, Donna / Cabrales, Pedro

    Clinical hemorheology and microcirculation

    2018  Volume 70, Issue 1, Page(s) 95–105

    Abstract: Background: In sickle cell disease (SCD), polymerization of hemoglobin S (HbS) leads to the formation of rigid, non-deformable sickled RBCs. Loss of RBC deformability, sickling and irreversible membrane damage causes abnormal blood rheology, and ... ...

    Abstract Background: In sickle cell disease (SCD), polymerization of hemoglobin S (HbS) leads to the formation of rigid, non-deformable sickled RBCs. Loss of RBC deformability, sickling and irreversible membrane damage causes abnormal blood rheology, and increases viscosity which contributes to vasoocclusion and other SCD pathophysiology. GBT440 (generic name voxelotor) is a novel anti-polymerization and anti-sickling agent currently undergoing clinical evaluation for the treatment of SCD.
    Objective: The purpose of this study was to determine the effects of GBT440 on deformability of sickle RBCs (SS RBCs) and the hyperviscosity of sickle cell blood (SS blood).
    Methods: The mechanical and rheological properties of GBT440-treated SS RBCs were measured using micropipette and filtration techniques. The viscosity of sickle blood was measured using a Wells-Brookfield cone/plate viscometer.
    Results: GBT440 restored movement of deoxygenated SS RBCs through a gel filtration column and reduced the pressure required to pass SS RBCs through a polycarbonate filter. Moreover, GBT440 decreased the membrane shear elastic modulus of SS RBCs assessed via micropipette aspiration and reduced the hyperviscosity of SS blood under deoxygenated conditions.
    Conclusions: GBT440 maintains SS RBC deformability and improves SS blood viscosity by inhibiting HbS polymerization under deoxygenated conditions. These results further support development of GBT440 as a disease-modifying agent in SCD patients.
    MeSH term(s) Anemia, Sickle Cell/blood ; Blood Viscosity/genetics ; Erythrocyte Deformability/physiology ; Erythrocytes, Abnormal/physiology ; Humans
    Language English
    Publishing date 2018-04-13
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 1381750-4
    ISSN 1875-8622 ; 1386-0291
    ISSN (online) 1875-8622
    ISSN 1386-0291
    DOI 10.3233/CH-170340
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: GBT021601 improves red blood cell health and the pathophysiology of sickle cell disease in a murine model.

    Dufu, Kobina / Alt, Carsten / Strutt, Steven / Partridge, James / Tang, Tzechiang / Siu, Vincent / Liao-Zou, Hilary / Rademacher, Peter / Williams, Alexander T / Muller, Cynthia R / Geng, Xin / Pochron, Mira Patel / Dang, Annie Nguyen / Cabrales, Pedro / Li, Zhe / Oksenberg, Donna / Cathers, Brian E

    British journal of haematology

    2023  Volume 202, Issue 1, Page(s) 173–183

    Abstract: The pathophysiologic mechanism of sickle cell disease (SCD) involves polymerization of deoxygenated haemoglobin S (HbS), leading to red blood cell (RBC) sickling, decreased RBC deformability, microvascular obstruction, haemolysis, anaemia and downstream ... ...

    Abstract The pathophysiologic mechanism of sickle cell disease (SCD) involves polymerization of deoxygenated haemoglobin S (HbS), leading to red blood cell (RBC) sickling, decreased RBC deformability, microvascular obstruction, haemolysis, anaemia and downstream clinical complications. Pharmacological increase in the concentration of oxygenated HbS in RBCs has been shown to be a novel approach to inhibit HbS polymerization and reduce RBC sickling and haemolysis. We report that GBT021601, a small molecule that increases HbS-oxygen affinity, inhibits HbS polymerization and prevents RBC sickling in blood from patients with SCD. Moreover, in a murine model of SCD (SS mice), GBT021601 reduces RBC sickling, improves RBC deformability, prolongs RBC half-life and restores haemoglobin levels to the normal range, while improving oxygen delivery and increasing tolerance to severe hypoxia. Notably, oral dosing of GBT021601 in animals results in higher levels of Hb occupancy than voxelotor and suggests the feasibility of once-daily dosing in humans. In summary, GBT021601 improves RBC health and normalizes haemoglobin in SS mice, suggesting that it may be useful for the treatment of SCD. These data are being used as a foundation for clinical research and development of GBT021601.
    MeSH term(s) Humans ; Animals ; Mice ; Hemolysis ; Disease Models, Animal ; Oxygen ; Anemia, Sickle Cell/drug therapy ; Erythrocytes ; Hemoglobins ; Hemoglobin, Sickle
    Chemical Substances Oxygen (S88TT14065) ; Hemoglobins ; Hemoglobin, Sickle
    Language English
    Publishing date 2023-03-24
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80077-6
    ISSN 1365-2141 ; 0007-1048
    ISSN (online) 1365-2141
    ISSN 0007-1048
    DOI 10.1111/bjh.18771
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  4. Article ; Online: Impact of Pharmacologically Left Shifting the Oxygen-Hemoglobin Dissociation Curve on Arterial Blood Gases and Pulmonary Gas Exchange During Maximal Exercise in Hypoxia.

    Stewart, Glenn M / Cross, Troy J / Joyner, Michael J / Chase, Steven C / Curry, Timothy / Lehrer-Graiwer, Josh / Dufu, Kobina / Vlahakis, Nicholas E / Johnson, Bruce D

    High altitude medicine & biology

    2021  Volume 22, Issue 3, Page(s) 249–262

    Abstract: ... Graiwer, Kobina Dufu, Nicholas E. Vlahakis, and Bruce D. Johnson. Impact of pharmacologically left ...

    Abstract Stewart, Glenn M., Troy J. Cross, Michael J. Joyner, Steven C. Chase, Timothy Curry, Josh Lehrer-Graiwer, Kobina Dufu, Nicholas E. Vlahakis, and Bruce D. Johnson. Impact of pharmacologically left shifting the oxygen-hemoglobin dissociation curve on arterial blood gases and pulmonary gas exchange during maximal exercise in hypoxia.
    MeSH term(s) Exercise Test ; Hemoglobins ; Humans ; Hypoxia ; Oxygen ; Oxygen Consumption ; Pulmonary Gas Exchange
    Chemical Substances Hemoglobins ; Oxygen (S88TT14065)
    Language English
    Publishing date 2021-06-21
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2076262-8
    ISSN 1557-8682 ; 1527-0297
    ISSN (online) 1557-8682
    ISSN 1527-0297
    DOI 10.1089/ham.2020.0159
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Increased hemoglobin affinity for oxygen with GBT1118 improves hypoxia tolerance in sickle cell mice.

    Dufu, Kobina / Williams, Alexander T / Muller, Cynthia R / Walser, Cynthia M / Lucas, Alfredo / Eaker, Allyn M / Alt, Carsten / Cathers, Brian E / Oksenberg, Donna / Cabrales, Pedro

    American journal of physiology. Heart and circulatory physiology

    2021  Volume 321, Issue 2, Page(s) H400–H411

    Abstract: Therapeutic agents that increase the Hb affinity for oxygen ( ... ...

    Abstract Therapeutic agents that increase the Hb affinity for oxygen (O
    MeSH term(s) Allosteric Regulation ; Anemia, Sickle Cell/metabolism ; Animals ; Benzaldehydes/pharmacology ; Brain/metabolism ; Cerebral Cortex/metabolism ; Disease Models, Animal ; Erythrocytes/drug effects ; Hematocrit ; Hematologic Agents/pharmacology ; Hemoglobin, Sickle/drug effects ; Hemoglobin, Sickle/metabolism ; Hypoxia/metabolism ; Mice ; Mice, Transgenic ; Niacinamide/analogs & derivatives ; Niacinamide/pharmacology ; Oxygen/metabolism ; Partial Pressure
    Chemical Substances Benzaldehydes ; GBT1118 ; Hematologic Agents ; Hemoglobin, Sickle ; Niacinamide (25X51I8RD4) ; Oxygen (S88TT14065)
    Language English
    Publishing date 2021-07-02
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 603838-4
    ISSN 1522-1539 ; 0363-6135
    ISSN (online) 1522-1539
    ISSN 0363-6135
    DOI 10.1152/ajpheart.00048.2021
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: GBT440 Inhibits Sickling of Sickle Cell Trait Blood Under

    Dufu, Kobina / Lehrer-Graiwer, Josh / Ramos, Eleanor / Oksenberg, Donna

    Hematology reports

    2016  Volume 8, Issue 3, Page(s) 6637

    Abstract: In sickle cell trait (SCT), hemoglobin A (HbA) and S (HbS) are co-expressed in each red blood cell (RBC). While homozygous expression of HbS (HbSS) leads to polymerization and sickling of RBCs resulting in sickle cell disease (SCD) characterized by ... ...

    Abstract In sickle cell trait (SCT), hemoglobin A (HbA) and S (HbS) are co-expressed in each red blood cell (RBC). While homozygous expression of HbS (HbSS) leads to polymerization and sickling of RBCs resulting in sickle cell disease (SCD) characterized by hemolytic anemia, painful vaso-occlusive episodes and shortened life-span, SCT is considered a benign condition usually with minor or no complications related to sickling. However, physical activities that cause increased tissue oxygen demand, dehydration and/or metabolic acidosis leads to increased HbS polymerization and life-threatening complications including death. We report that GBT440, an agent being developed for the treatment of SCD, increases the affinity of oxygen for Hb and inhibits
    Language English
    Publishing date 2016-09-28
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2586645-X
    ISSN 2038-8330 ; 2038-8322
    ISSN (online) 2038-8330
    ISSN 2038-8322
    DOI 10.4081/hr.2016.6637
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  7. Article ; Online: The effect of the antisickling compound GBT1118 on the permeability of red blood cells from patients with sickle cell anemia.

    Al Balushi, Halima / Dufu, Kobina / Rees, David C / Brewin, John N / Hannemann, Anke / Oksenberg, Donna / Lu, David C-Y / Gibson, John S

    Physiological reports

    2019  Volume 7, Issue 6, Page(s) e14027

    Abstract: Sickle cell anemia (SCA) is one of the commonest severe inherited disorders. Nevertheless, effective treatments remain inadequate and novel ones are avidly sought. A promising advance has been the design of novel compounds which react with hemoglobin S ( ... ...

    Abstract Sickle cell anemia (SCA) is one of the commonest severe inherited disorders. Nevertheless, effective treatments remain inadequate and novel ones are avidly sought. A promising advance has been the design of novel compounds which react with hemoglobin S (HbS) to increase oxygen (O
    MeSH term(s) Anemia, Sickle Cell/blood ; Anemia, Sickle Cell/diagnosis ; Anemia, Sickle Cell/drug therapy ; Antisickling Agents/pharmacology ; Benzaldehydes/pharmacology ; Cell Size/drug effects ; Erythrocyte Membrane/drug effects ; Erythrocyte Membrane/metabolism ; Hemoglobin, Sickle/metabolism ; Hemolysis/drug effects ; Humans ; Intermediate-Conductance Calcium-Activated Potassium Channels/antagonists & inhibitors ; Intermediate-Conductance Calcium-Activated Potassium Channels/blood ; Niacinamide/analogs & derivatives ; Niacinamide/pharmacology ; Oxygen/blood ; Permeability ; Symporters/antagonists & inhibitors ; Symporters/blood ; K Cl- Cotransporters
    Chemical Substances Antisickling Agents ; Benzaldehydes ; GBT1118 ; Hemoglobin, Sickle ; Intermediate-Conductance Calcium-Activated Potassium Channels ; KCNN4 protein, human ; Symporters ; Niacinamide (25X51I8RD4) ; Oxygen (S88TT14065)
    Language English
    Publishing date 2019-03-27
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2724325-4
    ISSN 2051-817X ; 2051-817X
    ISSN (online) 2051-817X
    ISSN 2051-817X
    DOI 10.14814/phy2.14027
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  8. Article ; Online: Effects of an allosteric hemoglobin affinity modulator on arterial blood gases and cardiopulmonary responses during normoxic and hypoxic low-intensity exercise.

    Stewart, Glenn M / Chase, Steven / Cross, Troy J / Wheatley-Guy, Courtney M / Joyner, Michael J / Curry, Timothy / Lehrer-Graiwer, Josh / Dufu, Kobina / Vlahakis, Nicholas E / Johnson, Bruce D

    Journal of applied physiology (Bethesda, Md. : 1985)

    2020  Volume 128, Issue 6, Page(s) 1467–1476

    Abstract: Numerous pathophysiological conditions induce hypoxemia-related cardiopulmonary perturbations, decrements in exercise capacity, and debilitating symptoms. Accordingly, this study investigated the efficacy of an allosteric hemoglobin modulator (voxelotor) ...

    Abstract Numerous pathophysiological conditions induce hypoxemia-related cardiopulmonary perturbations, decrements in exercise capacity, and debilitating symptoms. Accordingly, this study investigated the efficacy of an allosteric hemoglobin modulator (voxelotor) to enhance arterial oxygen saturation during low-intensity exercise in hypoxia. Eight normal healthy subjects (36 ± 7 yr; 73.8 ± 9.5 kg; 3 women) completed a submaximal cycling test (60 W) under normoxic ([Formula: see text]: 0.21; O
    MeSH term(s) Adult ; Exercise ; Female ; Hemoglobins ; Humans ; Hypoxia ; Male ; Oxygen ; Oxygen Consumption ; Pulmonary Gas Exchange
    Chemical Substances Hemoglobins ; Oxygen (S88TT14065)
    Language English
    Publishing date 2020-04-23
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 219139-8
    ISSN 1522-1601 ; 0021-8987 ; 0161-7567 ; 8750-7587
    ISSN (online) 1522-1601
    ISSN 0021-8987 ; 0161-7567 ; 8750-7587
    DOI 10.1152/japplphysiol.00185.2019
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  9. Article ; Online: GBT1118, a potent allosteric modifier of hemoglobin O

    Dufu, Kobina / Yalcin, Ozlem / Ao-Ieong, Eilleen S Y / Hutchaleelala, Athiwat / Xu, Qing / Li, Zhe / Vlahakis, Nicholas / Oksenberg, Donna / Lehrer-Graiwer, Josh / Cabrales, Pedro

    American journal of physiology. Heart and circulatory physiology

    2017  Volume 313, Issue 2, Page(s) H381–H391

    Abstract: Adaptation to hypoxia requires compensatory mechanisms that affect ... ...

    Abstract Adaptation to hypoxia requires compensatory mechanisms that affect O
    MeSH term(s) Adaptation, Physiological ; Administration, Oral ; Animals ; Benzaldehydes/administration & dosage ; Benzaldehydes/pharmacokinetics ; Benzaldehydes/pharmacology ; Biomarkers/blood ; Blood Flow Velocity ; Blood Pressure ; Disease Models, Animal ; Heart Rate ; Hypoxia/blood ; Hypoxia/drug therapy ; Hypoxia/physiopathology ; Male ; Mice, Inbred C57BL ; Microcirculation/drug effects ; Niacinamide/administration & dosage ; Niacinamide/analogs & derivatives ; Niacinamide/pharmacokinetics ; Niacinamide/pharmacology ; Oxygen/blood ; Oxyhemoglobins/metabolism ; Regional Blood Flow ; Severity of Illness Index ; Skin/blood supply
    Chemical Substances Benzaldehydes ; Biomarkers ; GBT1118 ; Oxyhemoglobins ; Niacinamide (25X51I8RD4) ; Oxygen (S88TT14065)
    Language English
    Publishing date 2017-05-19
    Publishing country United States
    Document type Journal Article
    ZDB-ID 603838-4
    ISSN 1522-1539 ; 0363-6135
    ISSN (online) 1522-1539
    ISSN 0363-6135
    DOI 10.1152/ajpheart.00772.2016
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  10. Article ; Online: A phase 1/2 ascending dose study and open-label extension study of voxelotor in patients with sickle cell disease.

    Howard, Jo / Hemmaway, Claire Jane / Telfer, Paul / Layton, D Mark / Porter, John / Awogbade, Moji / Mant, Timothy / Gretler, Daniel D / Dufu, Kobina / Hutchaleelaha, Athiwat / Patel, Mira / Siu, Vincent / Dixon, Sandra / Landsman, Noel / Tonda, Margaret / Lehrer-Graiwer, Joshua

    Blood

    2019  Volume 133, Issue 17, Page(s) 1865–1875

    Abstract: New treatments directly targeting polymerization of sickle hemoglobin (HbS), the proximate event in the pathophysiology of sickle cell disease (SCD), are needed to address the severe morbidity and early mortality associated with the disease. Voxelotor ( ... ...

    Abstract New treatments directly targeting polymerization of sickle hemoglobin (HbS), the proximate event in the pathophysiology of sickle cell disease (SCD), are needed to address the severe morbidity and early mortality associated with the disease. Voxelotor (GBT440) is a first-in-class oral therapy specifically developed to treat SCD by modulating the affinity of hemoglobin (Hb) for oxygen, thus inhibiting HbS polymerization and downstream adverse effects of hemolytic anemia and vaso-occlusion. GBT440-001 was a phase 1/2 randomized, double-blind, placebo-controlled, single and multiple ascending dose study of voxelotor in adult healthy volunteers and patients with SCD, followed by a single-arm, open-label extension study. This report describes results of voxelotor (500-1000 mg per day) in patients with sickle cell anemia. The study evaluated the safety, tolerability, pharmacokinetic, and pharmacodynamic properties of voxelotor and established proof of concept by improving clinical measures of anemia, hemolysis, and sickling. Thirty-eight patients with SCD received 28 days of voxelotor 500, 700, or 1000 mg per day or placebo; 16 patients received 90 days of voxelotor 700 or 900 mg per day or placebo. Four patients from the 90-day cohort were subsequently enrolled in an extension study and treated with voxelotor 900 mg per day for 6 months. All patients who received multiple doses of voxelotor for ≥28 days experienced hematologic improvements including increased Hb and reduction in hemolysis and percentage of sickled red cells, supporting the potential of voxelotor to serve as a disease-modifying therapy for SCD. Voxelotor was well tolerated with no treatment-related serious adverse events and no evidence of tissue hypoxia. These trials were registered at www.clinicaltrials.gov as #NCT02285088 and #NCT03041909.
    MeSH term(s) Adolescent ; Adult ; Anemia, Sickle Cell/drug therapy ; Benzaldehydes/pharmacokinetics ; Benzaldehydes/therapeutic use ; Case-Control Studies ; Cohort Studies ; Double-Blind Method ; Female ; Follow-Up Studies ; Hematologic Agents/pharmacokinetics ; Hematologic Agents/therapeutic use ; Humans ; Male ; Maximum Tolerated Dose ; Middle Aged ; Prognosis ; Pyrazines/pharmacokinetics ; Pyrazines/therapeutic use ; Pyrazoles/pharmacokinetics ; Pyrazoles/therapeutic use ; Tissue Distribution ; Young Adult
    Chemical Substances Benzaldehydes ; Hematologic Agents ; Pyrazines ; Pyrazoles ; voxelotor (3ZO554A4Q8)
    Language English
    Publishing date 2019-01-17
    Publishing country United States
    Document type Clinical Trial, Phase I ; Clinical Trial, Phase II ; Journal Article ; Randomized Controlled Trial ; Research Support, Non-U.S. Gov't
    ZDB-ID 80069-7
    ISSN 1528-0020 ; 0006-4971
    ISSN (online) 1528-0020
    ISSN 0006-4971
    DOI 10.1182/blood-2018-08-868893
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