A novel and simple hollow-fiber assay for in vivo evaluation of nonpeptidyl thrombopoietin receptor agonists

Xie, Conghua; Xu, Yongping; Zhao, Hongbing; Lou, Liguang

doi:10.1016/j.exphem.2012.01.010

Cited by 3 publications

(11 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These observations are not surprising in light of previous studies on the small molecule TPOR agonist eltrombopag, which resulted in bell-shaped doseresponse curves in receptor-expressing cell lines (Xie et al, 2012). In addition, eltrombopag triggered TPO-like STAT5 activation in CD34 1 CD41 2 progenitor cells, but in contrast to rhTPO, eltrombopag did not activate STAT3 or AKT in CD34 1 CD41 1 cells (Sun et al, 2012).…”

Section: Discussionsupporting

confidence: 59%

Discovery and Characterization of Nonpeptidyl Agonists of the Tissue-Protective Erythropoietin Receptor

et al. 2015

View full text Add to dashboard Cite

Erythropoietin (EPO) and its receptor are expressed in a wide variety of tissues, including the central nervous system. Local expression of both EPO and its receptor is upregulated upon injury or stress and plays a role in tissue homeostasis and cytoprotection. High-dose systemic administration or local injection of recombinant human EPO has demonstrated encouraging results in several models of tissue protection and organ injury, while poor tissue availability of the protein limits its efficacy. Here, we describe the discovery and characterization of the nonpeptidyl compound STS-E412 (2-[2-(4-chlorophenoxy) ethoxy]-5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidine), which selectively activates the tissue-protective EPO receptor, comprising an EPO receptor subunit (EPOR) and the common b-chain (CD131). STS-E412 triggered EPO receptor phosphorylation in human neuronal cells. STS-E412 also increased phosphorylation of EPOR, CD131, and the EPO-associated signaling molecules JAK2 and AKT in HEK293 transfectants expressing EPOR and CD131. At low nanomolar concentrations, STS-E412 provided EPO-like cytoprotective effects in primary neuronal cells and renal proximal tubular epithelial cells. The receptor selectivity of STS-E412 was confirmed by a lack of phosphorylation of the EPOR/EPOR homodimer, lack of activity in off-target selectivity screening, and lack of functional effects in erythroleukemia cell line TF-1 and CD341 progenitor cells. Permeability through artificial membranes and Caco-2 cell monolayers in vitro and penetrance across the blood-brain barrier in vivo suggest potential for central nervous system availability of the compound. To our knowledge, STS-E412 is the first nonpeptidyl, selective activator of the tissue-protective EPOR/CD131 receptor. Further evaluation of the potential of STS-E412 in central nervous system diseases and organ protection is warranted.

show abstract

Section: Discussionsupporting

confidence: 59%

Discovery and Characterization of Nonpeptidyl Agonists of the Tissue-Protective Erythropoietin Receptor

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Our previous study showed that hollow‐fibre assay using 32D‐MPL cells is a specific and efficient approach for rapidly evaluating the in vivo activity of small‐molecule TPOR agonists . Here, we used this assay to evaluate the pharmacodynamics of hetrombopag on the TPOR‐dependent signalling pathway and its relationship to the pharmacokinetics of hetrombopag.…”

Section: Resultsmentioning

confidence: 99%

“…The hollow‐fibre assay is currently in routine use as a screening tool for anticancer drug discovery . Our previous study showed that the 32D‐MPL hollow‐fibre assay was a specific and efficient model for rapidly evaluating the in vivo activity of small‐molecule TPOR agonists . Here, this assay was used to investigate the pharmacokinetic and pharmacodynamic characteristics of hetrombopag.…”

Section: Discussionmentioning

confidence: 99%

“…In vivo hollow‐fibre assays were performed as described previously . Briefly, a hollow fibre was filled with the cell suspension (1 × 10 7 cells/mL) and subsequently sealed in 2‐cm segments.…”

Section: Methodsmentioning

confidence: 99%

“…In vivo hollow-fibre assays were performed as described previously. 22 Briefly, a hollow fibre was filled with the cell suspension (1 × 10 7 cells/mL) and subsequently sealed in 2-cm segments. The hollow-fibre capsules were inserted into subcutaneous tissue through a 10-gauge trocar, after which mice were randomly assigned to control and treatment groups.…”

Section: Hollow-fibre Assaymentioning

confidence: 99%

See 2 more Smart Citations

Pharmacological characterization of hetrombopag, a novel orally active human thrombopoietin receptor agonist

Xie

Zhao

Bao

et al. 2018

J Cellular Molecular Medi

View full text Add to dashboard Cite

Nonpeptide thrombopoietin receptor (TPOR/MPL) agonists, such as eltrombopag, have been used to treat thrombocytopenia of various aetiologies. Here, we investigated the pharmacological properties of hetrombopag, a new orally active small‐molecule TPOR agonist, in preclinical models. Hetrombopag specifically stimulated proliferation and/or differentiation of human TPOR‐expressing cells, including 32D‐MPL and human hematopoietic stem cells, with low nanomolar EC 50 values through stimulation of STAT, PI3K and ERK signalling pathways. Notably, hetrombopag effectively up‐regulated G1‐phase–related proteins, including p‐RB, Cyclin D1 and CDK4/6, normalized progression of the cell cycle, and prevented apoptosis by modulating BCL‐XL/BAK expression in 32D‐MPL cells. Moreover, hetrombopag and TPO acted additively in stimulating TPOR‐dependent signalling, promoting cell viability, and preventing apoptosis. Orally administered hetrombopag specifically promoted the viability and growth of 32D‐MPL cells in hollow fibres implanted into nude mice with much higher potency than that of the well‐known TPOR agonist, eltrombopag, in association with activation of TPOR‐dependent signal transduction in vivo. Taken together, our findings indicate that, given its favourable pharmacological characteristics, hetrombopag may represent a new, orally active, small‐molecule TPOR agonist for patients with thrombocytopenia.

show abstract

Novel therapies for immune thrombocytopenia

Kuter

2021

Br J Haematol

View full text Add to dashboard Cite

Summary Current therapies for immune thrombocytopenia (ITP) are successful in providing a haemostatic platelet count in over two‐thirds of patients. Still, some patients have an inadequate response and there is a need for other therapies. A number of novel therapies for ITP are currently being developed based upon the current pathophysiology of ITP. Many therapies are targetted at reducing platelet destruction by decreasing anti‐platelet antibody production by immunosuppression with monoclonal antibodies targetted against CD40, CD38 and the immunoproteasome or physically reducing the anti‐platelet antibody concentration by inhibition of the neonatal Fc receptor. Others target the phagocytic system by inhibiting FcγR function with staphylococcal protein A, hypersialylated IgG, polymeric Fc fragments, or Bruton kinase. With a recognition that platelet destruction is also mediated by complement, inhibitors of C1s are also being tested. Inhibition of platelet desialylation may also play a role. Other novel therapies promote platelet production with new oral thrombopoietin receptor agonists or the use of low‐level laser light to improve mitochondrial activity and prevent megakaryocyte apoptosis. This review will focus on these novel mechanisms for treating ITP and assess the status of treatments currently under development. Successful new treatments for ITP might also provide a pathway to treat other autoimmune disorders.

show abstract

A novel and simple hollow-fiber assay for in vivo evaluation of nonpeptidyl thrombopoietin receptor agonists

Cited by 3 publications

References 19 publications

Discovery and Characterization of Nonpeptidyl Agonists of the Tissue-Protective Erythropoietin Receptor

Discovery and Characterization of Nonpeptidyl Agonists of the Tissue-Protective Erythropoietin Receptor

Pharmacological characterization of hetrombopag, a novel orally active human thrombopoietin receptor agonist

Novel therapies for immune thrombocytopenia

Contact Info

Product

Resources

About