Eltrombopag: a review of its use in patients with severe aplastic anaemia

Comparison of Thrombopoietin Receptor Agonists Plus Recombinant Human Thrombopoietin versus Recombinant Human Thrombopoietin Alone for Hematopoietic Reconstruction in Multiple Myeloma Patients Undergoing Autologous Hematopoietic Stem Cell Transplantation

BACKGROUND

Hetrombopag is a novel thrombopoietin receptor agonist that has shown an additive effect in stimulating platelet production when combined with recombinant human thrombopoietin (rhTPO). However, it remains unclear whether this combination can promote hematopoietic reconstruction after autologous stem cell transplant (ASCT).

PURPOSE

To compare the effect of rhTPO plus thrombopoietin receptor agonists (TPO-RA) versus rhTPO alone on hematopoietic recovery, adverse events, postoperative complications, and cost-effectiveness in patients with newly diagnosed multiple myeloma (NDMM) undergoing ASCT.

METHODS

A total of 67 consecutive NDMM patients who underwent ASCT at our hospital from January 2021 to May 2024 were included. Of these patients, 35 received a combination of rhTPO and the TPO-RA hetrombopag after stem cell reinfusion (observation group), whereas 32 patients received rhTPO alone (control group). Hematopoietic reconstitution between the two groups was compared.

RESULTS

Baseline clinical characteristics were similar between both groups. In the observation group, the median time to platelet recovery was 9 days after stem cell reinfusion, which was significantly shorter than that in the control group (P = .003). The mean number of platelet transfusions in the observation group was significantly lower than that in the control group (1.0 vs. 2.0 units, P = .034). All patients tolerated rhTPO and TPO-RA well, with no thrombotic events observed. Survival analysis showed no reduction in time to progression (TTP) and overall survival (OS) with the addition of TPO-RA. There were no statistical differences in the incidence of adverse events, drug expenses, and hospital stay between two groups (P  > 0.05).

CONCLUSIONS

Although sample size and study design limit the data from this study, our findings suggest that the combination of TPO-RA (hetrombopag) and rhTPO enhances platelet recovery in comparison with rhTPO alone, without increasing adverse effects.

Efficacy of Eltrombopag with Immunosuppressive Therapy Versus Immunosuppressive Therapy Alone on Severe Aplastic Anaemia: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

Severe aplastic anaemia (SAA) is a syndrome of bone marrow failure caused by T cell-mediated destruction of haematopoietic stem cells and progenitor cells. Whether patients with SAA should be treated with eltrombopag (EPAG) and immunosuppressive therapy (IST) or IST alone remains debatable. Therefore, we conducted this meta-analysis to compare the efficacy of eltrombopag + IST with that of IST alone in patients with SAA and to assess the difference in the efficacy of eltrombopag in adults and children.

METHODS

We performed this meta-analysis by retrieving studies that met the inclusion and exclusion criteria from PubMed, EMBASE, and the Cochrane Library up to 1 January 2023. We used a random-effects model to calculate odds ratios (ORs) with 95% confidence intervals (CIs) for primary and secondary outcomes. I² statistics were used to evaluate the heterogeneity of the included studies.

RESULTS

Six studies involving a total of 699 patients were included. In terms of the primary outcomes, our pooled results indicated that patients treated with EPAG + IST had a higher 6-month overall response rate (OR = 2.25; 95% CI, 1.60-3.16; p < 0.00001), a higher 6-month complete response rate (OR = 2.61; 95% CI, 1.82-3.74; p < 0.00001), and a lower 6-month nonresponse rate (OR = 0.32; 95% CI, 0.19-0.52; p < 0.00001). However, there was no significant difference in the rate of 6-month partial response (OR = 0.94; 95% CI, 0.49-1.81; p = 0.85).

CONCLUSION

This meta-analysis indicated that patients treated with additional eltrombopag for IST may have a higher rate of haematological response.

Orphan Drug Use in Patients With Rare Diseases: A Population-Based Cohort Study

Background: Orphan drugs are used for the diagnosis, prevention and treatment of rare diseases that, in the European Union, are defined as disorders affecting no more than 5 persons in 10,000. So far, a total of around 800 orphan medicinal products have been approved by the European Medicines Agency, however the utilization profile of orphan drugs has yet to be explored. This study aimed at assessing the utilization profile of orphan drugs authorized for marketing by the Italian Medicines Agency using population-based data. Methods: A total of 21 orphan drugs used in outpatient settings, approved in the European Union before or during the 2008-2018 period and involving 15 rare diseases, were included in the study. The monitored population included patients with one of the conditions surveilled by the population-based Tuscany Registry of Rare Diseases and diagnosed between 2000-2018. A multi-database approach was applied, by linking data from the registry with information collected in drug prescriptions databases. The prevalence and intensity of use were estimated for the selected orphan drugs and other non-orphan medications, used to treat the same rare disease and for which a change in the prevalence of use was hypothesized after authorization of the orphan drug. Results: For some diseases (acquired aplastic anemia, tuberous sclerosis complex, most metabolic diseases) a low prevalence of orphan drugs use was observed (range between 1.1-12.5%). Conversely, orphan drugs were frequently used in hemophilia B, Wilson disease and idiopathic pulmonary fibrosis (maximum of 78.3, 47.6 and 41.8%, respectively). For hemophilia B and Leber's hereditary optic neuropathy, there are currently no other medications used in clinical practice in addition to orphan drugs. Six orphan drugs were used for the treatment of pulmonary arterial hypertension, appearing the elective therapy for this disease, albeit with different utilization profiles (range of prevalence 1.7-55.6%). Conclusion: To the best of our knowledge, this is the first study investigating the utilization profile of orphan drugs prescribed in a defined geographical area, and providing relevant information to monitor over time potential changes in the prevalence of these medications as well as in the health care decision making.

Management of childhood aplastic anemia following liver transplantation for nonviral hepatitis: A French survey

BACKGROUND

Hepatitis-associated aplastic anemia (AA) is a rare syndrome combining acute hepatitis of variable severity and AA. Hepatitis may be severe enough to require urgent liver transplantation (LT). Herein, we describe clinical presentation and management of a cohort of pediatric patients diagnosed with AA after undergoing LT for nonviral hepatitis.

METHODS

To describe this rare clinical situation, we performed a national survey and identified nine children treated for AA following LT during the last 10 years in France.

RESULTS

All patients were treated first for hepatic failure with urgent LT. AA was diagnosed with a median delay of 34 days [21-200] from the diagnosis of hepatitis. Seven children were treated with antithymocyte globulin/cyclosporine, one with CSA alone and one received bone marrow transplantation. At the last visit (median follow-up: 4 years), outcomes were excellent: all patients were alive and in hematological remission (complete remission: 7; partial remission: 2). Immunosuppressive therapy was pursued in all patients due to the liver transplant. No unusual toxicities were reported.

CONCLUSION

AA after LT is considered a therapeutic challenge. Nevertheless, hematological outcome is good using a standard immunosuppressive approach.

Mechanisms and therapeutic prospects of thrombopoietin receptor agonists

The second-generation thrombopoietin (TPO) receptor agonists eltrombopag and romiplostim are potent activators of megakaryopoiesis and represent a growing treatment option for patients with thrombocytopenic hematological disorders. Both TPO receptor agonists have been approved worldwide for the treatment of children and adults with chronic immune thrombocytopenia. In the EU and USA, eltrombopag is approved for the treatment of patients with severe aplastic anemia who have had an insufficient response to immunosuppressive therapy and in the USA for the first-line treatment of severe aplastic anemia in combination with immunosuppressive therapy. Eltrombopag has also shown efficacy in several other disease settings, for example, chemotherapy-induced thrombocytopenia, selected inherited thrombocytopenias, and myelodysplastic syndromes. While both TPO receptor agonists stimulate TPO receptor signaling and enhance megakaryopoiesis, their vastly different biochemical structures bestow upon them markedly different molecular and functional properties. Here, we review and discuss results from preclinical and clinical studies on the functional and molecular mechanisms of action of this new class of drug.

In silico Selection and Experimental Validation of FDA-Approved Drugs as Anti-quorum Sensing Agents

The emergence of antibiotic resistant bacterial pathogens is increasing at an unprecedented pace, calling for the development of new therapeutic options. Small molecules interfering with virulence processes rather than growth hold promise as an alternative to conventional antibiotics. Anti-virulence agents are expected to decrease bacterial virulence and to pose reduced selective pressure for the emergence of resistance. In the opportunistic pathogen Pseudomonas aeruginosa the expression of key virulence traits is controlled by quorum sensing (QS), an intercellular communication process that coordinates gene expression at the population level. Hence, QS inhibitors represent promising anti-virulence agents against P. aeruginosa. Virtual screenings allow fast and cost-effective selection of target ligands among vast libraries of molecules, thus accelerating the time and limiting the cost of conventional drug-discovery processes, while the drug-repurposing approach is based on the identification of off-target activity of FDA-approved drugs, likely endowed with low cytotoxicity and favorable pharmacological properties. This study aims at combining the advantages of virtual screening and drug-repurposing approaches to identify new QS inhibitors targeting the pqs QS system of P. aeruginosa. An in silico library of 1,467 FDA-approved drugs has been screened by molecular docking, and 5 hits showing the highest predicted binding affinity for the pqs QS receptor PqsR (also known as MvfR) have been selected. In vitro experiments have been performed by engineering ad hoc biosensor strains, which were used to verify the ability of hit compounds to decrease PqsR activity in P. aeruginosa. Phenotypic analyses confirmed the impact of the most promising hit, the antipsychotic drug pimozide, on the expression of P. aeruginosa PqsR-controlled virulence traits. Overall, this study highlights the potential of virtual screening campaigns of FDA-approved drugs to rapidly select new inhibitors of important bacterial functions.

Eltrombopag in Immune Thrombocytopenia, Aplastic Anemia, and Myelodysplastic Syndrome: From Megakaryopoiesis to Immunomodulation

Eltrombopag is an orally available thrombopoietin receptor agonist indicated for the treatment of immune thrombocytopenia (ITP). Beyond the effect on megakaryopoiesis, the drug also showed a stimulating effect on the hematopoietic stem cell with consistent clinical efficacy in aplastic anemia (AA) and myelodysplastic syndromes (MDS). Eltrombopag is highly effective in ITP and less so in AA and MDS. This observation underlines the importance of residual normal hematopoiesis, which is maximal in ITP, minimal/absent in AA, and dysregulated in MDS. In ITP, the drug at 50-75 mg daily induced up to 85% responses both in clinical trials and real-life studies, with the possibility of tapering and discontinuation. In AA, eltrombopag at 150 mg daily was effective in about 40% of cases relapsed/refractory to standard immunosuppression or ineligible for bone marrow transplant. In MDS, the drug seems less effective, with responses in about a quarter of patients at various schedules. The efficacy of eltrombopag in ITP, AA, and MDS suggests the existence of common immune-pathological mechanisms in these diseases, including autoimmunity against peripheral blood cells and bone marrow precursors, as well as a possible evolution of one condition into the other. Additional mechanisms of action emerging from the clinical use of eltrombopag include modulation of T-regulatory cells, restoration of Fc-γ receptor balance in phagocytes, and an iron-mobilizing effect. In this review, we analyzed the most recent literature on eltrombopag use and efficacy in patients with ITP, AA, and MDS, exploring the basis for different dosing, combined treatments, and discontinuation in each context.

[Eltrombopag for refractory thrombocytopenia in patients with allogeneic hematopoietic stem cell transplantation]

目的

观察艾曲波帕治疗异基因造血干细胞（allo-HSCT）移植后难治性血小板减少的疗效及安全性。

方法

2015年5月1日至2016年5月1日，应用艾曲波帕治疗10例allo-HSCT后难治性血小板减少（糖皮质激素等治疗无效）患者。10例患者中，男、女各5例，中位年龄34(17~54）岁。急性髓系白血病5例，急性淋巴细胞白血病3例，重型再生障碍性贫血2例。同胞HLA配型全相合移植1例，单倍型相合移植9例。allo-HSCT至接受艾曲波帕治疗的中位时间为221(73~917) d。艾曲波帕剂量为50~75 mg/d（口服）。

结果

5例（50%）患者获得完全有效（PLT≥50×10⁹/L且脱离血小板输注），用药30 d累积完全有效率为35.7%，治疗后达到第1次PLT≥50×10⁹/L的中位时间为16(10~56) d。至随访截止，3例完全有效患者已分别停药39、342、84 d, PLT均≥100×10⁹/L。5例患者无效。未发生药物相关不良反应。

结论

艾曲波帕对于部分allo-HSCT后难治性血小板减少患者有效且耐受性良好，值得进一步研究。

Lusutrombopag: First Global Approval

Lusutrombopag (Mulpleta®) is an orally bioavailable, small molecule thrombopoietin (TPO) receptor agonist being developed by Shionogi for chronic liver disease (CLD) patients with thrombocytopenia prior to elective invasive surgery. Lusutrombopag acts selectively on the human TPO receptor and activates signal transduction pathways that promote the proliferation and differentiation of bone marrow cells into megakaryocytes, thereby increasing platelet levels. In September 2015, lusutrombopag received its first global approval in Japan for the improvement of CLD-associated thrombocytopenia in patients scheduled to undergo elective invasive procedures. This article summarizes the milestones in the development of lusutrombopag leading to this first approval.

Revealing eltrombopag's promotion of human megakaryopoiesis through AKT/ERK-dependent pathway activation

Eltrombopag is a small, non-peptide thrombopoietin mimetic that has been approved for increasing platelet count not only in immune thrombocytopenia and Hepatitis C virus-related thrombocytopenia, but also in aplastic anemia. Moreover, this drug is under investigation for increasing platelet counts in myelodysplastic syndromes. Despite current clinical practice, the mechanisms governing eltrombopag's impact on human hematopoiesis are largely unknown, in part due to the impossibility of using traditional in vivo models. To investigate eltrombopag's impact on megakaryocyte functions, we employed our established in vitro model for studying hematopoietic stem cell differentiation combined with our latest 3-dimensional silk-based bone marrow tissue model. Results demonstrated that eltrombopag favors human megakaryocyte differentiation and platelet production in a dose-dependent manner. These effects are accompanied by increased phosphorylation of AKT and ERK1/2 signaling molecules, which have been proven to be crucial in regulating physiologic thrombopoiesis. These data further clarify the different mechanisms of action of eltrombopag when compared to romiplostim, which, as we have shown, induces the proliferation of immature megakaryocytes rather than platelet production, due to the unbalanced activation of AKT and ERK1/2 signaling molecules. In conclusion, our research clarifies the underlying mechanisms that govern the action of eltrombopag on megakaryocyte functions and its relevance in clinical practice.