Eltrombopag: an oral thrombopoietin receptor agonist for the treatment of idiopathic thrombocytopenic purpura

Construction of Highly Functionalized C4-Oxyacylated and Aminated Pyrazolines

Pyrazolines and pyrazolones are prevalent cores in drugs and bioactive molecules. Functionalizing them with heteroatoms on the ring improves or expands their clinical efficacy. However, a general method to selectively heterofunctionalize them at C4 and C5 is still elusive. Herein, we have demonstrated an iodine(III)-mediated construction of C4-heterofunctionalized pyrazolines from α,β-unsaturated hydrazones. The oxyacylated and aminated products, bearing a tertiary as well as a secondary stereocenter, were obtained via aza-Michael, followed by a C-O/C-N bond formation. A deprotection/oxidation sequence produced pyrazolones in a quantitative yield.

Safety of non‑peptide thrombopoietin receptor agonists in patients with immune thrombocytopenia: A systematic review and meta‑analysis of short‑term double‑blind randomized clinical trials

The aim of the present study was to analyze the safety of non-peptide thrombopoietin receptor agonists (TPO-RAs) for immune thrombocytopenia (ITP) treatment. All studies reporting adverse events (AEs) in relation to ITP treatment with eltrombopag, avatrombopag, and hetrombopag were retrieved from PubMed, Web of Science, and Embase databases. RevMan 5.4.1 was used for meta-analysis, heterogeneity and bias analyses. A total of 1,078 patients from seven eligible studies were enrolled. In the enrolled clinical trials, the double-blind period was between 6 weeks and 6 months. The results revealed that the chances of any AEs [relative risk (RR)=1.16; 95% confidence interval (CI), 0.90-1.51; I²=78%; P=0.26], grade 3/4 AEs (RR=1.07; 95% CI, 0.63-1.80; I²=0%; P=0.81), elevated transaminase levels (RR=1.09; 95% CI, 0.68-1.74; I²=0%; P=0.72), thrombosis (RR=1.92; 95% CI, 0.55-6.66; I²=0%; P=0.31) and cataracts (RR=0.83; 95% CI, 0.38-1.83; I²=0%; P=0.65) were not significantly higher in patients with ITP that received non-peptide TPO-RAs compared with patients with ITP treated with a placebo. The present study indicated that non-peptide TPO-RAs were relatively safe for patients with ITP, at least within 6 months of administration.

A multicentre double-blind, double-dummy, randomised study of recombinant human thrombopoietin versus eltrombopag in the treatment of immune thrombocytopenia in Chinese adult patients

We performed a double-blind, double-dummy controlled study to compare the efficacy between recombinant human thrombopoietin (rhTPO) and eltrombopag in rapidly increasing the platelet counts in Chinese patients with immune thrombocytopenia (ITP). A total of 96 patients diagnosed with ITP for ≥6 months who had baseline platelet counts of <30 × 10⁹ /l were randomly assigned (1:1 ratio) to receive eltrombopag 25 mg/day or rhTPO 300 u/kg for 2 weeks. Compared with the eltrombopag group, a significantly higher proportion of patients in the rhTPO group achieved platelet counts of ≥50 × 10⁹ /l [75·00% (36/48) vs. 43·75% (21/48), P = 0·003] or complete response (64·58% vs. 25·00%) on day 15. Moreover, a higher proportion of patients in the rhTPO group either had platelet counts that rapidly increased to twice that of baseline and with platelet counts of ≥30 × 10⁹ /l, or reached ≥50 × 10⁹ /l at least once when analysed on day 9, 12, and 15. However, upon discontinuation of the treatment, the platelet counts reduced to the baseline within 1 week in the rhTPO group, but on the fourth week in the eltrombopag group. Adverse events were similar in patients given rhTPO and eltrombopag. To conclude, rhTPO is superior to eltrombopag at 25 mg/day in rapidly increasing platelet counts in patients with ITP (ClinicalTrials.gov Identifier: NCT03771378).

Pharmacokinetics of Eltrombopag in Healthy Chinese Subjects and Effect of Sex and Genetic Polymorphism on its Pharmacokinetic and Pharmacodynamic Variability

BACKGROUND AND OBJECTIVE

Eltrombopag is the first oral, small-molecule, non-peptide thrombopoietin receptor agonist for the treatment of idiopathic thrombocytopenic purpura. This study investigated the pharmacokinetics of eltrombopag in healthy Chinese subjects and evaluated the effect of sex and genetic polymorphisms on its variability.

METHODS

Forty-eight healthy subjects were administered a single dose of eltrombopag (25 mg). Plasma concentrations of eltrombopag were determined using a validated liquid chromatography-tandem mass spectrometry method, and platelet counts were determined by blood tests. CYP1A2 rs762551, CYP2C8*3 rs10509681, CYP2C8*3 rs11572080, UGT1A1 rs887829, UGT1A3 rs3806596, and BCRP rs2231142 polymorphisms were genotyped by Sanger sequencing. A back-propagation artificial neural network (BP-ANN) model was constructed to predict pharmacokinetics based on physiological factors and genetic polymorphism data.

RESULTS

Compared with male subjects, female subjects who received a single 25-mg dose of eltrombopag exhibited a significantly increased mean maximum plasma concentration (C_max) and significantly decreased apparent clearance. Additionally, CYP1A2 rs762551 C>A single nucleotide polymorphism influenced distribution and elimination. C-allele carriers exhibited 30% higher systemic exposure and 20% lower apparent clearance compared with homozygous A-allele carriers. Mean percentage increases in platelet counts from baseline to Day 5 were 9.38% and 17.06% in male and female subjects, respectively. The BP-ANN model had a high goodness-of-fit index and good coherence between predicted and measured concentrations (R = 0.98979).

CONCLUSION

Sex and CYP1A2 rs762551 C>A were associated with the pharmacokinetic variability of eltrombopag in healthy Chinese subjects. Females exhibited a better platelet-elevating effect compared with males administered the same dosage. The developed BP-ANN model based on physiological factors and genetic polymorphism data could be promising for applications in pharmacokinetic studies.

TRIAL REGISTRATIONS

https://www.Chinadrugtrials.org.cn CTR20190898.

Eltrombopag directly inhibits BAX and prevents cell death

The BCL-2 family protein BAX has essential activity in mitochondrial regulation of cell death. While BAX activity ensures tissue homeostasis, when dysregulated it contributes to aberrant cell death in several diseases. During cellular stress BAX is transformed from an inactive cytosolic conformation to a toxic mitochondrial oligomer. Although the BAX transformation process is not well understood, drugs that interfere with this process are useful research tools and potential therapeutics. Here, we show that Eltrombopag,  an FDA-approved drug,  is a direct inhibitor of BAX. Eltrombopag binds the BAX trigger site distinctly from BAX activators, preventing them from triggering BAX conformational transformation and simultaneously promoting stabilization of the inactive BAX structure. Accordingly, Eltrombopag is capable of inhibiting BAX-mediated apoptosis induced by cytotoxic stimuli. Our data demonstrate structure-function insights into a mechanism of BAX inhibition and reveal a mechanism for Eltrombopag that may expand its use in diseases of uncontrolled cell death.

Eltrombopag, oral immunosuppressant and androgen combination therapy in twelve patients with refractory severe aplastic anemia

Objective: Eltrombopag monotherapy or eltrombopag combined with immunosuppressant has achieved robust hematologic responses in severe aplastic anemia (SAA). In patients with refractory SAA, for whom hematopoietic stem cell transplantation is unavailable, we attempted to combine eltrombopag with oral immunosuppressant and androgen, to further improve hematologic response. Methods: We collected and analyzed data retrospectively from twelve refractory SAA cases who had received combination therapy of eltrombopag, oral immunosuppressant and androgen. All these patients had received intensive immunosuppressive treatment (IST) for more than 6 months and were evaluated as nonresponders. Results: A total of 12 SAA patients were treated with a combination of eltrombopag, an oral immunosuppressant (cyclosporine, N = 9; tacrolimus, N = 3) and androgen. The median maximum dose of eltrombopag was 75 mg/day (range, 75-150). After a median follow-up of 8.5 months (7-23), the overall response rate (ORR) was 42% (5/12, including trilineage, N = 4; hemoglobin + platelet, N = 1). Two of 5 responders reached normal blood counts. Optimal hematological response rates were reached at 6 months. The median increase in neutrophil, hemoglobin and platelet count were 1.64 × 10⁹ /L (0.71-2.66), 53 g/L (25-66.5) and 25 × 10⁹ /L (14-230), respectively. In general, the combination therapy was well tolerated; however, two patients suffered from non-lethal upper extremity venous thrombosis when they were platelet transfusion-dependent. Conclusion: Eltrombopag, oral immunosuppressant and androgen combination therapy in patients with IST-refractory SAA is feasible and could restore multi-lineage hematopoiesis. Thrombosis risk of eltrombopag still needs to be monitored.

Safety and Efficacy of Eltrombopag in Children and Adults with Immune Thrombocytopenia: A Systematic Review and Meta-Analysis

Immune thrombocytopenia is an immune condition where antibodies are produced against platelets. Eltrombopag is a thrombopoietin receptor agonist that stimulates and promotes platelet production approved for treating thrombocytopenia in patients with chronic immune thrombocytopenia, where other treatments such as corticosteroids, splenectomy or immunoglobulins are inadequate. The aim of this meta-analysis was to evaluate the efficacy and safety of the eltrombopag in adults and children with immune thrombocytopenia. We included 7 studies with a total of 765 patients (606 adults and 159 children). We evaluated the number of patients that achieved a post-treatment platelet count equal or above 50x10⁹/L (primary result-target) without the need of rescue treatment for at least 4 weeks. Our data showed that patients who received eltrombopag were almost 4 times more probable in achieving the primary target when compared to patients who received placebo (RR 3.84, 95% CI 2.39 to 6.14; I² = 46%). The number of patients needed rescue treatment and the number of bleeding incidents were reduced in the group that received eltrombopag when compared to those who received placebo (RR 0.40, 95% CI 0.25 to 0.62; I² = 40%) (RR 0.74, 95% CI 0.62 to 0.89; I² = 68%). The total number of side effects did not statistically differ between the two groups (RR 0.99, 95% CI 0.90 to 1.08; I² = 14%). Our findings were similar to previously published studies and confirm that eltrombopag is safe and efficient in immune thrombocytopenia. However, more clinical trials are needed in order to enhance our findings.

Thrombopoietin Receptor Agonists in Children with Immune Thrombocytopenia: A New Therapeutic Era

BACKGROUND AND OBJECTIVE

Immune thrombocytopenia (ITP) is a common bleeding disorder in childhood. The management of ITP in children is controversial, requiring personalized assessment of patients and therapeutic choices. Thrombopoietin receptor agonists (TPO-RAs), eltrombopag and romiplostim, have been shown to be safe and effective for the treatment of pediatric ITP. The aim of our research is to define the role of thrombopoietin receptor agonists in the management of pediatric ITP.

METHODS

This review focuses on the use of TPO-RAs in pediatric ITP, in randomized trials and in clinical routine, highlighting their key role in the management of the disease.

RESULTS

Eltrombopag and romiplostim appear effective treatment options for children with ITP. Several clinical studies have assessed that the use of TPO-RAs increases platelet count, decreases bleeding symptoms and improves health-related quality of life. Moreover, TPO-RAs are well tolerated with minor side effects.

CONCLUSION

Although long term efficacy and safety of TPO-RAs still require further investigations, their use is gradually expanding in the clinical practice of children with ITP.

Platelet and liver regeneration after liver surgery

The success of liver surgery, including resection and transplantation, is largely dependent on the ability of the liver to regenerate. Despite substantial improvement in surgical techniques and perioperative care, one of the main concerns is post-hepatectomy liver failure and early allograft dysfunction, both of which are associated with impaired liver regeneration. Recent studies have demonstrated the positive role of platelets in promoting liver regeneration and protecting hepatocytes; however, the underlying mechanisms responsible for these effects are not fully understood. In this review, we updated the accumulated evidence of the role of platelets in promoting liver regeneration, with a focus on liver resection and liver transplantation. The goal of these studies was to support the clinical implementation of platelet agents, such as thrombopoietin receptor agonists, to augment liver regeneration after liver surgery. This "platelet therapy" may become a treatment choice for post-hepatectomy liver failure and early allograft dysfunction.

Synthesis and Biological Activity of N-(arylsulfonyl) Valine Hydrazones and Assistance of NMR Spectroscopy for Definitive 3D Structure

Background:

Hydrazide-hydrazones constitute an important class of compounds for new drug development. In this study, a series of 39 new acylhydrazones (3-41), derived from (2S)-3-methyl- 2-[[(4-methylphenyl)sulfonyl]amino]butanoic acid hydrazide were synthesized with further aim to achieve biologically active acylhydrazones carrying an amino acid side chain.

Methods:

Compounds 3-41 were synthesized by microwave-assisted method. All synthesized compounds have been tested for their anti-HIV activity compound 21 was subjected to a new set of 2DNMR analysis for the characterization of the isomers in solution and determination of its 3D structure.

Results:

The IC50 values for compounds 2-40 were found between >125-10.90 µg/ml against HIV- 1(IIIB) and HIV-2(ROD) strains in MT-4 cells. Compounds 3, 6, 10, 12, 23, 24, 27, 32, and 37 with CC50 values between 10.90-14.50 µg/ml were selected to evaluate for their antileukemia activity. IC50 values for these mentioned compounds were found as >100μM on human chronic myelogenous leukemia, K562 cell line.

Conclusion:

Some compounds with IC50 values between 10.90-14.50 μg/ml will be of benefit in the development of novel leads.

Eltrombopag: Efficacy and Safety in Steroid Refractory Lupus-Associated Immune Thrombocytopenia

BACKGROUND

Eltrombopag, a thrombopoietin receptor agonist, is effective in chronic immune thrombocytopenia (ITP). The data in lupus ITP are sparse. This study aimed to assess the efficacy and safety of eltrombopag in lupus ITP.

METHODS

This is a single-center study conducted between 2012 and 2017 of 12 subjects with systemic lupus erythematosus-associated ITP. Patients with inadequate or suboptimal response to steroids and other immunosuppressants treated with eltrombopag were included in the study. Time taken for response to therapy (defined as platelets >1 lakh), dose, duration of treatment, and adverse effects of the drug were noted.

RESULTS

A total of 12 subjects were included in the study. The median platelet count at initiation of eltrombopag was 19,000 per μL. The time taken for response to therapy was 8 days. The median platelet count at 1-month follow-up was 241,000 per μL. All patients were concurrently treated with steroids and other immunosuppressants. Sustained benefit after stopping eltrombopag was noted in all patients. No adverse events including thrombotic complication were noted.

CONCLUSIONS

Eltrombopag is a new drug in our arsenal for treatment of ITP in lupus. It is a rapidly effective, safe, and orally administered medication. It indirectly contributes to reduction in the dose of steroids and immunosuppressants, thereby minimizing their cumulative adverse effects. It is a promising and safe option for the treatment of lupus-associated thrombocytopenia, but this needs further confirmation from multicenter, multiethnic, randomized controlled trials.

Balancing Therapy with Thrombopoietin Receptor Agonists and Splenectomy in Refractory Immune Thrombocytopenic Purpura: A Case of Postsplenectomy Thrombocytosis Requiring Plateletpheresis

Immune thrombocytopenic purpura (ITP) causes thrombocytopenia through the autoimmune destruction of platelets. Corticosteroids remain the first line of therapy, and traditionally splenectomy has been the second. While the availability of thrombopoietin receptor agonists (TPO-RAs) has expanded treatment options, there is little data for the ideal management of these agents in preparation for splenectomy. Thrombocytosis has been reported after splenectomy in patients treated with TPO-RA preoperatively, with one prior case requiring plateletpheresis for symptomatic thrombocytosis. We present a case report and review of the literature pertaining to this complication and provide recommendations for preventing postsplenectomy thrombocytosis in ITP patients on TPO-RAs.

Eltrombopag interference in routine chemistry testing

BACKGROUND

High doses of Eltrombopag have been previously reported to cause bilirubin interference. Following receipt of a sample from a patient receiving high-dose Eltrombopag therapy, the laboratory decided to investigate the effect of this drug on routine chemistry testing.

METHODS

Interference studies were performed by spiking Eltrombopag into aliquots of a serum pool to give concentrations ranging from 0 to 500 µg/mL. The following analytes, namely albumin, alkaline phosphatase, alanine transaminase, aspartate transaminase, Urea, total calcium, cholesterol, triglycerides, glucose, high-density lipoprotein cholesterol, iron, magnesium, inorganic phosphate, creatinine, bicarbonate, transferrin, ferritin, electrolytes, total and direct bilirubin and serum indices (hemolysis, icterus and lipaemia) were then measured on the Roche Cobas 6000 chemistry analyzer (Roche, Indianapolis, USA).

RESULTS

Eltrombopag interference (>10% change of the baseline value) was observed for total cholesterol, triglycerides, inorganic phosphate and high-density lipoprotein cholesterol. Clinical significant interference was observed for total cholesterol, inorganic phosphate and high-density lipoprotein cholesterol

CONCLUSIONS

Presence of high Eltrombopag concentrations in blood samples has been demonstrated to cause interference in the measurement of certain spectrophotometric-based assays on the Roche Cobas 6000 analyzer.

The JAK-STAT pathway: impact on human disease and therapeutic intervention

The Janus kinase (JAK)-signal transducer of activators of transcription (STAT) pathway is now recognized as an evolutionarily conserved signaling pathway employed by diverse cytokines, interferons, growth factors, and related molecules. This pathway provides an elegant and remarkably straightforward mechanism whereby extracellular factors control gene expression. It thus serves as a fundamental paradigm for how cells sense environmental cues and interpret these signals to regulate cell growth and differentiation. Genetic mutations and polymorphisms are functionally relevant to a variety of human diseases, especially cancer and immune-related conditions. The clinical relevance of the pathway has been confirmed by the emergence of a new class of therapeutics that targets JAKs.

Eltrombopag as steroid sparing therapy for immune thrombocytopenic purpura in systemic lupus erythematosus

BACKGROUND

Eltrombopag activates the thrombopoietin (TPO) surface receptor on the megakaryocyte, which increases the production of platelets, and rapidly improves circulating platelet numbers in patients with immune thrombocytopenic purpura (ITP). This allows for rapid tapering and/or cessation of corticosteroid therapy. Less is known about the platelet response to this drug in ITP associated with systemic lupus erythematosus (SLE).

METHODS

A retrospective review was performed of the clinical course of three consecutive patients, each with SLE-associated ITP who were initially treated with corticosteroids or other immunomodulatory therapy. These patients were treated with eltrombopag at the DMC Center for Bleeding Disorders and Thrombosis. Eltrombopag was administered according the package insert, with an initial dose of 50 mg daily, with weekly, then monthly monitoring of platelet counts and dose adjustments. Some immunomodulatory agents (e.g. hydroxychloroquine) were continued to control non hematologic SLE manifestations.

RESULTS

All three patients maintained acceptable platelet counts (>50,000/mm(3) for >3 years) following tapering and cessation of corticosteroids. The drug was well-tolerated and there were no adverse events, and specifically no thrombotic events.

CONCLUSION

Eltrombopag is effective as a rapidly acting corticosteroid sparing therapy for patients with ITP associated with SLE. This is important in reducing corticosteroid related side effects and morbidities in treating SLE patients with ITP. Larger studies are needed to ascertain safety and efficacy of eltrombopag in SLE patients with ITP, particularly those with coexisting antiphospholipid antibodies.

Eltrombopag in chronic hepatitis C

Chronic hepatitis C is a public health problem worldwide. Unfortunately, not all patients may benefit from antiviral therapy due to thrombocytopenia. Its causes are represented by portal hypertension and platelet sequestration in the spleen, decreased serum levels or activity of thrombopoietin, the bone marrow suppression induced by hepatitis C virus and a possible adverse effect of interferon. Thrombopoietin receptor analogs may contribute to increase platelet counts in these patients. Eltrombopag binds to another region of the thrombopoietin receptor compared to endogenous thrombopoietin and stimulates the proliferation and maturation of megakaryocytes and the platelet production in a dose-dependent manner. Eltrombopag has proven its effectiveness for the treatment of patients with primary immune thrombocytopenia. Its indication for other hemopathies or situations (like thrombocytopenia secondary to chemo- or radiotherapy, acute leukemia, myelodysplastic syndroms, acquired and hereditary bone marrow failure, and platelet donors) is under study. Eltrombopag may be particularly useful in patients with advanced chronic hepatitis or liver cirrhosis who require antiviral treatment. We present a minireview on the results of treatment with eltrombopag in patients chronically infected with hepatitis C virus, highlighting the benefits and mentioning possible adverse effects. In some studies eltrombopag increased the number of virological responses after clasical antiviral treatment of patients with chronic hepatitis C and reduced the transfusional requirements of those who had to be subjected to invasive surgery. Eltrombopag is a solution for many of these patients, which allows them receiving antiviral therapy and sometimes getting a sustained virological response, but they must be well monitored to prevent possible thromboembolic or bone marrow complications or liver failure occurrence.

Exome sequencing reveals a thrombopoietin ligand mutation in a Micronesian family with autosomal recessive aplastic anemia

We recently identified 2 siblings afflicted with idiopathic, autosomal recessive aplastic anemia. Whole-exome sequencing identified a novel homozygous missense mutation in thrombopoietin (THPO, c.112C>T) in both affected siblings. This mutation encodes an arginine to cysteine substitution at residue 38 or residue 17 excluding the 21-amino acid signal peptide of THPO receptor binding domain (RBD). THPO has 4 conserved cysteines in its RBD that form 2 disulfide bonds. Our in silico modeling predicts that introduction of a fifth cysteine may disrupt normal disulfide bonding to cause poor receptor binding. In functional assays, the mutant-THPO-containing media shows two- to threefold reduced ability to sustain UT7-TPO cells, which require THPO for proliferation. Both parents and a sibling with heterozygous R17C change have reduced platelet counts, whereas a sibling with wild-type sequence has normal platelet count. Thus, the R17C partial loss-of-function allele results in aplastic anemia in the homozygous state and mild thrombocytopenia in the heterozygous state in our family. Together with the recent identification of THPO receptor (MPL) mutations and the effects of THPO agonists in aplastic anemia, our results have clinical implications in the diagnosis and treatment of patients with aplastic anemia and highlight a role for the THPO-MPL pathway in hematopoiesis in vivo.

The role of eltrombopag in the management of hepatitis C virus-related thrombocytopenia

Eltrombopag is a 2nd generation thrombopoietin-receptor agonist. It binds with the thrombopoietin-receptors found on the surfaces of the megakaryocytes & increases platelet production. Many recent studies have suggested a potential role for this novel agent in the treatment of thrombocytopenia associated with hepatitis-C infection. Studies have shown that adjunct treatment with Eltrombopag can help avoid dose reductions/withdrawals of pegylated interferon secondary to thrombocytopenia. It may also have a role in priming up platelet levels to help initiate antiviral therapy. Similarly, chronic liver disease patients with thrombocytopenia who need to undergo an invasive procedure may be potential candidates for short two-week courses of eltrombopag in the periprocedural period to help reduce the risk of bleeding. Besides the price (deemed very expensive and probably not cost-effective), there are some legitimate concerns about the safety profile of this novel agent (most importantly, portal vein thrombosis, bone marrow fibrosis and hepatotoxicity). In this article, the potential role of eltrombopag in the context of hepatitis C virus (HCV)-related thrombocytopenia is reviewed. To write this article, a MEDLINE search was conducted (1990 to November 2012) using the search terms “eltrombopag,” “HCV,” and “thrombocytopenia.”