Eltrombopag for post-transplant cytopenias due to poor graft function. Bone Marrow Transplant. 2019;54:1346-1353. [PMID: 30679824 DOI: 10.1038/s41409-019-0442-3]

Treatment of post-allogeneic hematopoietic stem cell transplant cytopenias with sequential doses of multipotent mesenchymal stromal/stem cells

BACKGROUND AIMS

Cytopenias after allogeneic stem cell transplantation (allo-SCT) are a common complication, the underlying pathogenic mechanisms of which remain incompletely understood. Multipotent mesenchymal stromal/stem cell (MSC) therapy has been successfully employed in the treatment of immune-related disorders and can aid in the restoration of the hematopoietic niche.

METHODS

A phase II clinical trial to assess the efficacy and safety of administering four sequential doses of ex-vivo expanded bone marrow MSCs from a third-party donor to patients with persistent severe cytopenias after allo-SCT was performed.

RESULTS

The overall response rate on day 90 was 75% among the 27 evaluable patients (comprising 12 complete responses, 8 partial responses, and 7 with no response). The median time to respond was 14.5 days. Responses were observed across different profiles, including single or multiple affected lineages, primary or secondary timing, and potential immune-mediated or post-infectious pathophysiology versus idiopathic origin. With a median follow-up for surviving patients of 85 months after MSC infusion, 53% of patients are alive. Notably, no adverse events related to MSC therapy were reported.

CONCLUSIONS

In summary, the sequential infusion of third-party MSCs emerges as a viable and safe therapeutic option, exhibiting potential benefits for patients experiencing cytopenias following allo-SCT.

Eltrombopag treatment in thrombocytopenia following hematopoietic stem cell transplantation: A multicenter real-world experience

INTRODUCTION

Thrombocytopenia is among the most common complications following hematopoietic stem cell transplantation and is associated with increased mortality and morbidity with no standard treatment yet. In this multicenter and retrospective study, we aim to present our multi-center experience of Eltrombopag treatment in patients with isolated thrombocytopenia following HSCT.

MATERIAL-METHOD

A total of 73 patients from 5 centers who underwent autologous or allogeneic stem cell transplantation, had no primary disease relapse, all of whom had neutrophil engraftment, complete chimerism, and who were diagnosed with Prolonged Isolated Thrombocytopenia (PIT) or Secondary Failure Of Platelet Recovery (SFPR) were included in the study. The patients were initiated on Eltrombopag at a dose of 50-150 mg. Complete response was defined as a platelet count >50×109/L for 7 consecutive days with no transfusion support.

RESULTS

A total of 50.3% of the patients underwent Autologous and 49.7% Allogeneic Stem Cell Transplantation, 54.8% were diagnosed with PIT, and 45.2% were diagnosed with SFPR, and the treatment with 50-150 mg/day Eltrombopag was initiated on the median day +42. Complete response was achieved in 71.2% of these patients on the median day 23 of the treatment. No significant effects of the initial dose (50-150 mg/day) were detected in the Complete Response in the multivariate analysis on response. An insufficient number of Megakaryocytes in the bone marrow before Eltrombopag treatment was determined as an independent risk factor in determining the response (OR 3.57, 95% CI 1.21-10.55). The overall survival of the patients who did not respond to Eltrombopag was found to be significantly worse than that of patients who responded (p=0.022, HR:2.74, 95% CI 1.12-6.54).

CONCLUSION

As a result of the present study, Eltrombopag treatment was found to be effective and safe in thrombocytopenia that develops following hematopoietic stem cell transplantation. It was concluded that its use may be more effective in patients with sufficient bone marrow megakaryocytes before the treatment and an initial dose of 50 mg/day may be appropriate in terms of cost, effectiveness, and toxicity. Large-scale randomized and controlled prospective studies are needed to determine the roles of Eltrombopag treatment in patients with post-transplant PIT and SFPR.

Eltrombopag can promote platelet implantation after allogeneic hematopoietic stem cell transplantation as safely and similarly to thrombopoietin

Background

Eltrombopag has demonstrated efficacy in treating low platelet (PLT) levels, but it remains unclear whether eltrombopag can promote PLT engraftment after hematopoietic stem cell transplantation (HSCT).

Methods

Forty-one HSCT patients received eltrombopag 50 mg/d from +1 day until PLT >50 × 109/L or 1 month after HSCT. Fifty-one patients in the same period received thrombopoietin (TPO) to promote PLT graft after HSCT and served as a control group.

Results

A total of 51 patients who applied TPO during the same period were treated as a control. In the eltrombopag group, the median time to white blood cells (WBC) graft was 12 days (range, 10-17 days) and the PLT graft was 15 days (range, 10-30 days), whereas for the patients in the TPO group, the median time to WBC and PLT graft was 12 days (range, 9-23 days) and 15.5 days (range, 9-41 days), respectively. In the first month after HSCT, the median WBC count in the eltrombopag group was 4.41 × 109/L (range, 0.87-40.01 × 109/L) and the median PLT was 89x109/L (range, 30-401 × 109/L); the median WBC and PLT \counts in the TPO group were 4.65 × 109/L (range, 0.99-23.63 × 109/L) and 86 × 109/L (range, 5-512 × 109/L), respectively. Patients in the TPO or eltrombopag group did not experience serious side effects after drug administration, and the difference in side effects on liver and kidney function between the two groups was not statistically significant.

Conclusion

Eltrombopag is safe and similarly promotes platelet engraftment to thrombopoietin after allogeneic HSCT.

The state of the art in the treatment of severe aplastic anemia: immunotherapy and hematopoietic cell transplantation in children and adults

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure where marrow disruption is driven by a cytotoxic T-cell-mediated autoimmune attack against hematopoietic stem cells. The key diagnostic challenge in children, but also in adults, is to exclude the possible underlying congenital condition and myelodysplasia. The choice of treatment options, either allogeneic hematopoietic cell transplantation (alloHCT) or immunosuppressive therapy (IST), depends on the patient's age, comorbidities, and access to a suitable donor and effective therapeutic agents. Since 2022, horse antithymocyte globulin (hATG) has been available again in Europe and is recommended for IST as a more effective option than rabbit ATG. Therefore, an update on immunosuppressive strategies is warranted. Despite an improved response to the new immunosuppression protocols with hATG and eltrombopag, some patients are not cured or remain at risk of aplasia relapse or clonal evolution and require postponed alloHCT. The transplantation field has evolved, becoming safer and more accessible. Upfront alloHCT from unrelated donors is becoming a tempting option. With the use of posttransplant cyclophosphamide, haploidentical HCT offers promising outcomes also in AA. In this paper, we present the state of the art in the management of severe AA for pediatric and adult patients based on the available guidelines and recently published studies.

Management of chemotherapy-induced thrombocytopenia: guidance from the ISTH Subcommittee on Hemostasis and Malignancy

Thrombocytopenia is a common adverse effect of chemotherapy. The development of chemotherapy-induced thrombocytopenia (CIT) is influenced by cancer type and therapy, occurring in approximately one-third of patients with a solid tumor diagnosis and half of all patients with a hematologic malignancy. CIT may complicate the administration of chemotherapy, leading to therapeutic delays or dose reductions. This guidance document, presented by the International Society on Thrombosis and Haemostasis (ISTH) Subcommittee on Hemostasis and Malignancy, provides a comprehensive summary of the evidence and offers direction on the use of thrombopoietin receptor agonists (TPO-RAs) in various settings of CIT, including solid tumors, acute myeloid leukemia, stem cell transplant, and lymphoma. Studies have shown that TPO-RAs can improve platelet counts in CIT, but the clinical benefits of TPO-RA in terms of reducing bleeding, limiting platelet transfusion, avoiding chemotherapy delay, or dose reduction are uncertain. Further research is needed to optimize the selection of appropriate indications and study design to manage thrombocytopenia following chemotherapy.

Eltrombopag for the Treatment of Allogeneic Hematopoietic Stem Cell Transplantation-Related Poor Graft Function

INTRODUCTION

Allogeneic stem cell transplantation (ASCT) is a crucial therapeutic strategy for hematological and non-hematological disorders. Poor graft function (PGF) after ASCT presents a critical challenge that does not have a standardized treatment approach. A thrombopoietin-mimetic oral drug eltrombopag shows promise in some bone failure syndromes. This study aimed to analyze the efficacy of eltrombopag in treating PGF after ASCT.

METHODS

Patients receiving eltrombopag for PGF after ASCT between 2017 and 2020 were retrospectively evaluated. Patients' characteristics, details for ASCT, timing, treatment, and possible contributors for PGF, response to eltrombopag treatment, and overall response rate (ORR) were analyzed.  Results: Eighteen patients were assessed. Eltrombopag treatment yielded a favorable response in 11 patients, resulting in an ORR of 61%. The ORR in secondary PGF was better than that in primary PGF (83% and 17% respectively). There was a marked enhancement in platelet and hemoglobin levels following eltrombopag treatment (p=0.001 and p=0.030, respectively), while neutrophil values exhibited no significant change (p=0.8). Among the responding patients, four individuals (22%) underwent a tapering and discontinuation of eltrombopag. No toxicity was observed above grade one, and no patient discontinued eltrombopag because of intolerability or adverse events.

CONCLUSION

Our findings affirm that eltrombopag can treat poor graft function after allogeneic stem cell transplantation without significant toxicities. These results contribute to the growing body of evidence supporting the use of eltrombopag in poor graft function after allogeneic stem cell transplantation, providing insights into its potential benefits and limitations.

Definitions, incidence and outcome of poor graft function after hematopoietic cell transplantation: A systematic review and meta-analysis

Poor graft function (PGF) after allogeneic hematopoietic stem cell transplantation (HCT) is a serious complication with high morbidity and mortality. The reported incidence of PGF, its risk factors and outcome vary substantially between studies. This variability may be explained by heterogeneity in patient cohorts and HCT strategies, differences in the underlying causes of cytopenia, as well as by differences in PGF definition. In this systematic review and meta-analysis, we provide an overview of the various PGF definitions used and determined the impact of this variability on the reported incidence and outcome. We searched MEDLINE, EMBASE and Web of Science up to July 2022, for any study on PGF in HCT recipients. We performed random-effect meta-analyses for incidence and outcome and subgroup analyses based on different PGF criteria. Among 69 included studies (14.265 HCT recipients), we found 63 different PGF definitions, using various combinations of 11 common criteria. The median incidence of PGF was 7% (IQR: 5-11%, 22 cohorts). The pooled survival of PGF patients was 53% (95% CI: 45-61%, 23 cohorts). The most commonly reported risk factors associated with PGF were history of cytomegalovirus infection and prior graft-versus-host disease. Incidence was lower in studies with strict cytopenic cutoffs, while survival was lower for primary compared to secondary PGF. This work indicates that a standardized, quantitative definition of PGF is needed to facilitate clinical guideline development and to advance scientific progress.

Poor graft function after haploidentical stem cell transplantation with post-transplant cyclophosphamide

This is a retrospective cohort study of consecutive adult patients who received a haploidentical-SCT (haplo-SCT) with post-transplant cyclophosphamide (PT-Cy) in a single centre. Poor graft function (PGF) was defined as the occurrence of either persistent neutropenia (ANC < 0.5 × 10⁹/µL) with poor response to granulocyte colony-stimulating factors (G-CSF) and/or thrombocytopenia (platelets < 20 × 10⁹/L) with transfusion dependence, with complete donor chimerism and without concurrent severe GVHD or underlying disease relapse, during the first 12 months after transplantation. Forty-four (27.5%) out of 161 patients were diagnosed with PGF. Previous CMV reactivation was significantly more frequent in patients with PGF (88.6% versus 73.5%, p = 0.04) and the number of reactivations was also higher in these patients. Besides, early CMV reactivations in the first 6 months post-SCT were also significantly more frequent among patients with PGF (88.6% versus 71.8% p = 0.025). Thirty-two percent of patients with PGF were treated with increasing doses of thrombopoietin-receptor agonists (TRA) and 7 patients were treated with a donor CD34 + selected boost. In total, 93.2% of patients reached adequate peripheral blood counts in a median time of 101 days (range 11-475) after diagnosis. PGF is a frequent complication after haplo-SCT with PT-Cy. CMV reactivation might be the most relevant factor associated to its development. Even when most patients recover peripheral counts with support therapy, there is a group of patients with persistent cytopenias who can effectively be treated with TRA and/or a boost of CD34 + selective cells.

CD34 Stem Cell Boost in Pediatric Allogeneic Stem Cell Transplant Recipients: A Case Series and Review of Literature

Patients with poor graft function (PGF) or declining donor chimerism (DC) post allogeneic hematopoietic cell transplantation (HCT) may benefit from a CD34-selected stem cell boost (SCB). We retrospectively studied outcomes of fourteen pediatric patients (PGF: 12 and declining DC: 2), with a median age of 12.8 (range 0.08-20.6) years at HCT, who received a SCB. Primary and secondary endpoints included resolution of PGF or improvement in DC (≥ 15% increase), overall survival (OS) and transplant-related mortality (TRM), respectively. The median CD34 dose infused was 7.47 × 10⁶/kg (range 3.51 × 10⁶-3.39 × 10⁷/kg). Among patients with PGF who survived ≥ 3 months post-SCB (n = 8), we observed a non-significant decrease in the cumulative median number of red cell transfusions, platelet transfusions, and GCSF but not intravenous immunoglobulin doses in the 3 months before and after SCB. Overall response rate (ORR) was 50%, with 29% complete and 21% partial responses. ORR was better in recipients who received lymphodepletion (LD) pre-SCB versus none (75% versus 40%; p = 0.56). The incidence of acute and chronic graft-versus-host-disease was 7% and 14%, respectively. The 1-year OS was 50% (95% CI 23-72%) and TRM was 29% (95% CI 8-58%). SCB was effective in half of our cohort with possible benefit of LD pre-SCB.

[Graft failure, poor graft function erythroblastopenia: Actualization of definitions, diagnosis and treatment: Guidelines from the SFGM-TC]

In this article, we discuss again the definition, the risk factor and guideline to treat the graft failure, the poor graft function and erythrobalstopenia. Graft failure is a severe but rare complication after hematopoietic cell transplantation (HCT). Despite disparity in the literature, we defined this complication and discussed the factor risks and recommendation for treatment based on new studies. Poor graft function is also a more frequent complication after HCT. New studies will soon be available to prove or not the current recommendation suggested in this article based on therapeutics medicine or cellular therapy. Erythroblastopenia, is a rarer complication post HCT. Despite anticipation for a better choice of compatibility donor/recipient, some patients still suffer from this complication.

EHA Guidelines on Management of Antithrombotic Treatments in Thrombocytopenic Patients With Cancer

In cancer patients, thrombocytopenia can result from bone marrow infiltration or from anticancer medications and represents an important limitation for the use of antithrombotic treatments, including anticoagulant, antiplatelet, and fibrinolytic agents. These drugs are often required for prevention or treatment of cancer-associated thrombosis or for cardioembolic prevention in atrial fibrillation in an increasingly older cancer population. Data indicate that cancer remains an independent risk factor for thrombosis even in case of thrombocytopenia, since mild-to-moderate thrombocytopenia does not protect against arterial or venous thrombosis. In addition, cancer patients are at increased risk of antithrombotic drug-associated bleeding, further complicated by thrombocytopenia and acquired hemostatic defects. Furthermore, some anticancer treatments are associated with increased thrombotic risk and may generate interactions affecting the effectiveness or safety of antithrombotic drugs. In this complex scenario, the European Hematology Association in collaboration with the European Society of Cardiology has produced this scientific document to provide a clinical practice guideline to help clinicians in the management of patients with cancer and thrombocytopenia. The Guidelines focus on adult patients with active cancer and a clear indication for anticoagulation, single or dual antiplatelet therapy, their combination, or reperfusion therapy, who have concurrent thrombocytopenia because of either malignancy or anticancer medications. The level of evidence and the strength of the recommendations were discussed according to a Delphi procedure and graded according to the Oxford Centre for Evidence-Based Medicine.

Exploring the Potential of Eltrombopag: Room for More?

Since its introduction in clinical practice, eltrombopag (ELT) has demonstrated efficacy in heterogeneous clinical contexts, encompassing both benign and malignant diseases, thus leading researchers to make a more in-depth study of its mechanism of action. As a result, a growing body of evidence demonstrates that ELT displays many effects ranging from native thrombopoietin agonism to immunomodulation, anti-inflammatory, and metabolic properties. These features collectively explain ELT effectiveness in a broad spectrum of indications; moreover, they suggest that ELT could be effective in different, challenging clinical scenarios. We reviewed the extended ELT mechanism of action in various diseases, with the aim of further exploring its full potential and hypothesize new, fascinating indications.

Efficacy and Immunomodulating Properties of Eltrombopag in Aplastic Anemia following Autologous Stem Cell Transplant: Case Report and Review of the Literature

Thrombopoietin receptor agonists (TPO-RA) are currently indicated for the treatment of chronic immune thrombocytopenia and relapsed refractory aplastic anemia. However, the off-label use of these drugs is more and more frequent, including in the setting of aplasia secondary to chemotherapy and hemopoietic stem cell transplant (SCT). Growing evidence suggests that mechanisms of action of TPO-RA go beyond the TPO-receptor stimulation and point at the immunomodulating properties of these drugs. Here, we present a case of prolonged bone marrow aplasia secondary to autologous SCT treated with eltrombopag. We describe the clinical efficacy and the immunomodulating effect of this drug on inflammatory cytokine profile and bone marrow histology. Furthermore, we provide a review of the most recent literature highlighting the efficacy and safety of TPO-RA after SCT and chemotherapy for hematologic conditions.

Thrombocytopenia and Therapeutic Strategies after Allogeneic Hematopoietic Stem Cell Transplantation

Thrombocytopenia following allogeneic hematopoietic stem cell transplantation is a usual complication and can lead to high morbidity and mortality. New strategies, such as the use of another graft versus host-disease prophylaxis, alternative donors, and management of infections, have improved the survival of these patients. The mechanisms are unknown; therefore, the identification of new strategies to manage this potentially serious problem is needed. Thrombopoietin receptor agonists are currently available to stimulate platelet production. Some small retrospective studies have reported their potential efficacy in an allogeneic stem cell transplant setting, confirming good tolerability. Recent studies with higher numbers of patients also support their safety and efficacy in this setting, hence establishing the use of these drugs as a promising strategy for this post-transplant complication. However, prospective trials are needed to confirm these results.

Primary graft failure following allogeneic hematopoietic stem cell transplantation: risk factors, treatment and outcomes

OBJECTIVES

Graft failure (GF) is an intractable complication of transplantation, which can severely affect the efficacy of the graft; however, the characteristics, incidence, and risk factors of primary GF have not been well described. This study aimed to analyze the risk factors and outcomes of primary GF to swiftly identify high-risk patients for GF.

METHODS

We performed a case-control study with a case-control ratio of 1:4 with 869 patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) between January 2015 and December 2019 at our center.

RESULTS

Nineteen (2.19%) patients experienced primary poor graft function (PGF), while eleven (1.27%) patients developed primary graft rejection (GR). Univariate and multivariate logistic analyses identified two independent risk factors for primary PGF: splenomegaly [P = 0.030; odds ratio (OR), 3.486; 95% confidence interval (CI), 1.139 to 13.109], and donor type [non-matched sibling donor (non-MSD)] (P = 0.018; OR, 4.475; 95% CI, 1.289 to 15.537). However, only donor type (non-MSD) was statistically significant (P = 0.020; OR, 19.432; 95% CI, 1.595 to 236.691) for primary GR. The overall survival was significantly lower in the primary PGF (P = 0.001) and GR group (P = 0.000), respectively, compared to the control group.

CONCLUSION

GF can significantly affect the overall survival of patients who underwent allo-HSCT, despite its considerably low incidence. A human leukocyte antigen-matched sibling donor should be the first choice for patients undergoing allo-HSCT for the prevention of GF. Moreover, splenomegaly is an independent risk factor for PGF, and caution must be exercised while treating such patients.

Eltrombopag for Post-Transplant Poor Graft Function in East Asian Patients

Poor graft function (PGF) is a serious, potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation. Eltrombopag has shown multilineage responses in patients with refractory severe aplastic anemia, supporting the idea that it may improve cytopenia in patients with PGF. This retrospective, single center analysis included 8 Korean patients receiving eltrombopag for PGF. Median interval between transplant and eltrombopag treatment was 73 days, and the median duration treatment was 3.5 weeks. With median maximum daily dose of 50 mg, the time to best response was 93 days. Median hemoglobin increased from 8.2 g/dL to 10.9 g/dL, platelet from 18.5 × 10⁹/L to 54 × 10⁹/L, and absolute neutrophil count from 1.25 × 10⁹/L to 3.32 × 10⁹/L. In conclusion, eltrombopag is a good option for PGF in Korean patients, even at a lower dose compared to western patients.

Efficacy and safety of thrombopoietin receptor agonists in the treatment of thrombocytopenia after hematopoietic stem cell transplantation: a meta-analysis and systematic review

Thrombocytopenia is a tough complication after hematopoietic stem cell transplantation (HSCT) with elusive pathogenesis and lack of well-established therapies. Thrombopoietin receptor agonists (TPO-RAs) have been used for thrombocytopenia post HSCT in recent years, but the outcomes remain debatable. We conducted this meta-analysis and systematic-review to evaluate the efficacy and safety of TPO-RAs for platelet recovery after HSCT. We searched PubMed, EMBASE, and Cochrane databases for studies on the application of TPO-RAs (eltrombopag and romiplostim) in the settings of primary or secondary thrombocytopenia after HSCT by 17 March 2021. Efficacy outcomes included response rate and survival rate, and adverse events were also evaluated. A total of 19 studies involving 378 patients were included. The pooled response rate was 73% (95%CI: 68-78%), which was significantly higher than recombinant human thrombopoietin (rhTPO) (27.8%). The pooled survival rate was 66% (95%CI: 54-77%), and infection was found to be the main cause of death. In addition, the pooled rate of adverse events was 3% (95%CI: 1-7%), with no severe adverse events reported. TPO-RAs could effectively and safely promote the recovery of platelets in patients after HSCT.

Eltrombopag in the treatment of patients with persistent thrombocytopenia after haploidentical peripheral blood stem cell transplantation: a single-center experience

Persistent thrombocytopenia (PT) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is associated with an increased risk of bleeding and poor survival. The exact pathogenesis underlying PT remains unclear, and its management is difficult. Here we conducted a retrospective study to evaluate the efficacy and safety of eltrombopag (EPAG) in 34 patients with PT after allo-HSCT. Seven patients suffered from prolonged isolated thrombocytopenia (PIT), and 27 had secondary failure of platelet recovery (SFPR). For most patients, the initial dose was 25 mg or 50 mg daily, then adjusted to the maximum dose of 50-100 mg per day according to the response of platelet recovery and toleration of patients. The cumulative incidence (CI) of platelet recovery to at least 20 × 10⁹/L and 50 × 10⁹/L without transfusion support for at least 7 days was 72.1% and 60.7%, respectively. Nineteen (86.4%) of 22 responders were able to taper off the medication; furthermore, the platelet counts remained stable 1 month after withdrawal of EPAG. Although two patients discontinued EPAG during treatment due to headache and nausea, no patients developed grade 3 or 4 toxicities. Hypoplasia of bone marrow and decreased megakaryocytes (MKs) were found to be risk factors for overall response (OR) and complete response (CR) in multivariate analysis, respectively. Overall, our results indicated that EPAG can be used in the treatment of PT and that continuous exposure to EPAG may not be necessary.

Off-Label Use of Thrombopoietin Receptor Agonists: Case Series and Review of the Literature

Since their license in 2008, studies on thrombopoietin receptor agonists (TPO-RAs) are proceeding at a fast pace. Their favorable efficacy and safety profile makes them good candidates for the management of thrombocytopenia in different settings, even beyond their current indications. In the last 10 years, we faced patients with refractory thrombocytopenia that required treatment with off-label TPO-RA, despite the paucity of data in the literature and the possible risks, particularly that of thrombosis. We hereby report our 10-year real-life single-center experience of TPO-RA used off-label. Fourteen patients were divided into three groups according to the etiology of thrombocytopenia: myelodysplastic syndromes, post-transplantation, and lymphoproliferative diseases. Clinical features and results are reported within each group. Overall, TPO-RA proved effective in all these conditions achieving responses also in heavily pretreated patients. The overall response rate (ORR) was 100% in patients with thrombocytopenia after transplantation and in those with lymphoproliferative diseases and 75% in patients with myelodysplastic syndromes. The median duration of therapy was 285 days (range 93–1,513 days). Four patients (29%) discontinued treatment because of lack of response (n=2) or a sustained response (n=2). No grade 3–4 adverse events occurred, particularly no thrombosis. In our real-life experience, TPO-RAs were effective and safe and proved of value in the challenging management of patients with refractory thrombocytopenia associated with different conditions.

Outcomes with CD34-Selected Stem Cell Boost for Poor Graft Function after Allogeneic Hematopoietic Stem Cell Transplantation: A Systematic Review and Meta-Analysis

Poor graft function (PGF) is a life-threatening complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT) characterized by multilineage cytopenia in the absence of mixed donor chimerism (<95% donor), relapse, or severe graft-versus-host disease (GVHD). We present a systemic review and meta-analysis aimed at assessing the outcomes with CD34-selected stem cell boost (SCB) for PGF in adult allo-HSCT recipients. We screened a total of 1753 records identified from 4 databases (PubMed, Embase, Cochrane, and ClinicalTrials.gov) following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, using the search terms "hematological malignancies," "hematopoietic stem cell transplantation," "CD34 antigen(s)," "graft failure," and "poor graft function," from the date of inception to January 2021. After excluding review, duplicate, and nonrelevant articles, we included 7 studies reporting outcomes following administration of CD34-selected SCB for PGF after allo-HSCT, including hematologic complete response (CR) and overall response rate (ORR), GVHD, and overall survival (OS). Quality evaluation was done using the National Institutes of Health quality assessment tool. Pooled analysis was done using the R 'meta' package, and proportions with 95% confidence intervals (CIs) were computed. The inter-study variance was calculated using the Der Simonian-Laird estimator. We identified 209 patients who received CD34-selected SCB for PGF after allo-HSCT. The median age was 49 years (range, 18 to 69 years), and 61% were men. Primary graft sources included peripheral blood stem cells (72%) and bone marrow (28%). Donor types were matched sibling (37%), matched unrelated (36%), mismatched unrelated (22%), and haploidentical donors (5%). The median time from allo-HSCT to SCB was 138 days (range, 113 to 450 days). The median SCB dose was 3.45 × 10⁶ CD34 cells/kg (range, 3.1 to 4.9 × 10⁶ cells/kg). CR and ORR were 72% (95% CI, 63% to 79%; I² = 26%) and 80% (95% CI, 74% to 85%; I² = 0%), respectively. After a median follow-up of 42 months (range, 30 to 77 months), the actuarial survival rate was 54% (95% CI, 47% to 61%; I² = 0%). OS ranged from 80% at 1 year to 40% at 9 years. The incidences of acute and chronic GVHD after SCB were 17% (95% CI, 13% to 23%; I² = 0%) and 18% (95% CI, 8% to 34%; I² = 76%), respectively. Nonrelapse mortality was reported in 42 patients, with a pooled rate of 27% (95% CI, 17% to 40; I² = 59%), and death due to relapse was reported in 25 patients, with a pooled rate of 17% (95% CI, 11% to 23%; I² = 0%). Our data show that CD34-selected SCB improves outcomes after PGF post allo-HSCT with an acceptable toxicity profile. The literature lacks high-quality randomized evidence, and there remains an unmet need for prospective studies to address the optimal dosing and manipulation of SCB. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Use of eltrombopag for the treatment of poor graft function after hematopoietic stem cell transplantation in children

The main objective of this study was to determine whether Eltrombopag, a synthetic thrombopoietin receptor agonist, could improve peripheral blood counts in the three hematopoietic lineages and achieve transfusion independence in children with poor graft function (PGF) after allogenic hematopoietic stem cell transplantation (HSCT). Retrospective study of patients under 18 years who developed PGF post-HSCT in a large tertiary institution between January 2013 and March 2019. Out of 198 allogeneic HSCT, five patients met PGF criteria and were treated with eltrombopag. Median time from HSCT to eltrombopag initiation was 120 days. The median starting dose was 50 mg/day and the maximum dose reached was 75 mg/day. Median treatment duration was 9 months. Three patients achieved complete response and one partial response. The median dose among responders was 75 mg/day and the median time to response 8 weeks. Responses were sustained in three patients and two required a booster dose of CD34⁺ -selected cells from the original donor. None of the patients had to stop treatment due to adverse effects. The use of eltrombopag in children with PGF achieved responses in 80% of cases and demonstrated to be an effective and safe therapeutic option in pediatric patients with PGF.

Eltrombopag for the treatment of poor graft function following allogeneic stem cell transplant: a retrospective multicenter study

This retrospective study assessed the effectiveness of eltrombopag (EPAG), a thrombopoietin receptor agonist, in the treatment of poor graft function (PGF) following an allogeneic haemopoietic stem cell transplantation (HSCT). Complete response was defined as normalization of blood counts, whereas partial response was defined as transfusion independence. A total of 48 patients with full donor chimerism after HSCT, received EPAG for a median of 120 days (range 10-591). Patients with uni- bi- or tri-lineage cytopenia started treatment at a median of 95 days (range 17-877) after HSCT. The overall response rate was 75%: 24 patients had a complete response and 12 had a partial response. Positive predictors of response were an HLA-matched donor, a CD34⁺ dose at transplant > 4 × 10⁶/kg, and starting EPAG treatment at least 90 days after HSCT. Patients with more than one positive predictor had a response rate of 92% for the overall patient cohort and 94% for patients with tri-lineage cytopenia. One-year survival was 89% for complete responders, 60% for partial responders and 20% for non-responders (p = 0.0004). EPAG improves peripheral blood counts in patients with poor graft function following HSCT. Response to EPAG can be predicted and has a significant impact on survival.

Eltrombopag-related renal vein thromboembolism in a patient with immune thrombocytopenia: A case report

BACKGROUND

Eltrombopag is an orally administered thrombopoietin receptor agonist linked to a heightened risk of treatment-related thromboembolism. Both venous and arterial thromboses have been documented in the medical literature.

CASE SUMMARY

In the absence of nephropathy, a 48-year-old patient receiving eltrombopag for immune thrombocytopenia (ITP) developed renal vein thrombosis and pulmonary embolism. The renal vein thrombus spontaneously resolved during subsequent anticoagulant treatment, restoring venous circulation.

CONCLUSION

A rapid upsurge in platelets, rather than their absolute number, may trigger thrombotic events in this setting. For patients at high thrombotic risk, individualized eltrombopag dosing and vigilance in platelet monitoring are perhaps needed during treatment of ITP.

Challenges and Advances in Managing Thrombocytopenic Cancer Patients

Cancer patients have varying incidence, depth and duration of thrombocytopenia. The mainstay of managing severe chemotherapy-induced thrombocytopenia (CIT) in cancer is the use of platelet transfusions. While prophylactic platelet transfusions reduce the bleeding rate, multiple unmet needs remain, such as high residual rates of bleeding, and anticancer treatment dose reductions/delays. Accordingly, the following promising results in other settings, antifibrinolytic drugs have been evaluated for prevention and treatment of bleeding in patients with hematological malignancies and solid tumors. In addition, Thrombopoeitin receptor agonists have been studied for two major implications in cancer: treatment of severe thrombocytopenia associated with myelodysplastic syndrome and acute myeloid leukemia; primary and secondary prevention of CIT in solid tumors in order to maintain dose density and intensity of anti-cancer treatment. Furthermore, thrombocytopenic cancer patients are often prescribed antithrombotic medication for indications arising prior or post cancer diagnosis. Balancing the bleeding and thrombotic risks in such patients represents a unique clinical challenge. This review focuses upon non-transfusion-based approaches to managing thrombocytopenia and the associated bleeding risk in cancer, and also addresses the management of antithrombotic therapy in thrombocytopenic cancer patients.

Immune cytopenia after allogeneic haematopoietic stem-cell transplantation: challenges, approaches, and future directions

Immune-mediated cytopenia after allogeneic haematopoietic stem-cell transplantation is rare. The pathophysiology of immune-mediated anaemia, thrombocytopenia, and neutropenia, which occur alone or in combination with other cytopenias, is unclear and most probably a consequence of immune dysregulation. Risk factors for this complication have been identified in retrospective studies but these should be interpreted with caution and should not be generalised to this heterogeneous patient population. Diagnosis is challenging, requires awareness of such complications, and has to be differentiated from a multitude of other, and sometimes overlapping, possible complications. The clinical course of immune-mediated cytopenia is highly variable. Treatment requires an interdisciplinary approach and ranges from observation to symptomatic measures and directed therapies. Intensive immunosuppression is associated with an increased risk of infections and relapse, and current treatments are based on approaches in patients who have not undergone transplantation. Plasma cell-directed therapies, immunomodulation, and receptor-stimulating agents can be used to treat immune-mediated cytopenia.

Phase I Dose-Finding, Safety, and Tolerability Trial of Romiplostim to Improve Platelet Recovery After UCB Transplantation

Platelet recovery is delayed after umbilical cord blood transplant (UCBT). Romiplostim is a thrombopoietin receptor agonist that has the potential to improve platelet engraftment after UCBT. The purpose of this study was to determine the safety profile and maximum tolerated dose (MTD) of romiplostim and to investigate whether romiplostim accelerates platelet recovery post-UCBT. It was a single-center, dose-finding, safety and tolerability phase I trial of weekly romiplostim in 20 adult patients who failed to achieve an un-transfused platelet count of 20 × 10⁹/L by day +28 post-UCBT. Romiplostim was administered at the assigned dose as 6 weekly injections beginning by day +42 post-UCBT. Four dose levels (4, 6, 8, and 10 µg/kg per dose) were evaluated. The MTD of romiplostim was determined by the continual reassessment method, with a goal to identify a dose level with desired toxicity rate of ≤20%. Median age of the patients was 59.5 years, and 60% were female. Eleven patients received nonmyeloablative (NMA) double UCBT, seven patients received myeloablative single UCBT, and two patients received NMA single UCBT. Two patients received 4 µg/kg per dose, two received 6 µg/kg per dose, four received 8 µg/kg per dose, and the remaining 12 received 10 µg/kg per dose. Only five patients completed the full six doses of treatment. Of the 15 patients who received fewer than six doses, 12 were due to a platelet count of >100 × 10⁹/L, two were due to platelet count of >400 × 10⁹/L, and one was due to right upper extremity edema without thrombosis. All romiplostim-treated patients achieved platelet engraftment to 20 × 10⁹/L at a median of 45 days post-UCBT compared to 90% of controls at a median of 45 days (P = .08). Similarly, 90% of romiplostim-treated patients achieved platelet engraftment to 50 × 10⁹/L at a median of 48 days compared to 75% of controls at a median of 52 days (P = .09). All dose levels were effective with low toxicity; therefore, the MTD of romiplostim was 10 µg/kg per dose, and romiplostim is a safe and potentially effective therapy to counter delayed platelet recovery post-UCBT.

Impaired Hematopoiesis after Allogeneic Hematopoietic Stem Cell Transplantation: Its Pathogenesis and Potential Treatments

Impaired hematopoiesis is a serious complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Bone marrow aplasia and peripheral cytopenias arise from primary and secondary graft failure or primary and secondary poor graft function. Chimerism analysis is useful to discriminate these conditions. By determining the pathogenesis of impaired hematopoiesis, a timely and appropriate treatment can be performed. Hematopoietic system principally consists of hematopoietic stem cells and bone marrow microenvironment termed niches. Abnormality in hematopoietic stem and progenitor cells and/or abnormality in the relevant niches give rise to hematological diseases. Allo-HSCT is intended to cure each hematological disease, replacing abnormal hematopoietic stem cells and bone marrow niches with hematopoietic stem cells and bone marrow niches derived from normal donors. Therefore, treatment for graft failure and poor graft function after allo-HSCT is required to proceed based on determining the pathogenesis of impaired hematopoiesis. Recent progress in this area suggests promising treatment manipulations for graft failure and poor graft function.

Allogeneic hematopoietic stem cell transplantation in aplastic anemia: current indications and transplant strategies

Treatment options for newly diagnosed aplastic anemia (AA) patient includes upfront allogeneic hematopoietic stem cell transplant (HSCT) or immunosuppressive therapy (IST). With recent advances in supportive care, conditioning regimens and post-transplant immunosuppression the overall survival for HSCT approaches 70-90%. Transplant eligibility needs to be assessed considering age, comorbidities, donor availability and probability of response to immunosuppressive therapy (IST). Upfront HSCT should be offered to children and young adults with matched related donor (MRD). Upfront HSCT may also be offered to children and young adults with rapidly available matched unrelated donor (MUD) who require urgent HSCT. Bone marrow (BM) graft source and cyclosporine (CsA) plus methotrexate (MTX) as graft versus host disease (GVHD) prophylaxis are preferable when using anti-thymocyte globulin (ATG) based conditioning regimens. Alemtuzumab is an acceptable alternative to ATG and is used with CsA alone and with either BM or peripheral blood stem cells (PBSC). Cyclophosphamide (CY) plus ATG conditioning is preferable for patients receiving MRD transplant, while Fludarabine (Flu) based conditioning is reserved for older adults, those with risk factors of graft failure and those receiving MUD HSCT. For haploidentical transplant, use of low dose radiotherapy and post-transplant cyclophosphamide has resulted in a marked reduction in graft failure and GVHD.

Rescue treatment with eltrombopag in refractory cytopenias after allogeneic stem cell transplantation

Background:

Patients with post-transplant cytopenias due to poor graft function or primary engraftment failure show poor prognosis with a high mortality rate mainly because of graft versus host disease (GVHD), infection and/or bleeding. Treatment options are scarce and a CD34+ stem cell boost or a second bone marrow transplantation may be required to restore adequate haematopoiesis.

Methods:

In the present study patients with primary engraftment failure (n = 1) and refractory poor graft function (n = 11) were treated with eltrombopag in a single centre. The reason for eltrombopag treatment was trilineage cytopenia in six patients, bilineage cytopenia in three patients and single lineage cytopenia in three patients. Eltrombopag was initiated at a median of 214 (range: 120–877) days after haematopoietic stem cell transplantation (HCST) and administered for a median time of 114 (range: 12 days to >490) days. In 8/12 patients eltrombopag was introduced at a dose of 75 mg/day and then increased to 150 mg/day after 1 week; 1 patient was given 50 mg eltrombopag per day, and 3 patients received 75 mg daily.

Results:

In 10/12 patients eltrombopag significantly enhanced blood count values and patients became transfusion independent. Once stable haematological response was obtained, treatment was tapered until final discontinuation in 9/10 responding patients. No grade 3 or 4 toxicities were observed. At time of last follow up, 3/12 patients were dead, 2 due to disease relapse, 1 due to GVHD and pneumonia. All patients except one maintained their complete response and remain transfusion independent at a median of 858 (range: 429–1119) days.

Conclusion:

These preliminary data confirm that eltrombopag is able to rescue multilineage haematopoiesis in patients with treatment-refractory cytopenias after allogeneic HSCT.

The Successful Sequential Use of Plerixafor and Eltrombopag For Hematopoietic Cell Transplantation in a Child With High-risk Neuroblastoma

High-dose chemotherapy with autologous hematopoietic stem cell transplantation improves event-free survival in patients with high-risk neuroblastoma. However, in heavily pretreated patients, poor marrow function can be an obstacle in the successful proceeding of therapy. Priming with plerixafor plus filgrastim is an option for effective mobilization and collection of stem cells. In addition, thrombopoietin agonist eltrombopag can improve the outcome of posttransplantation thrombocytopenia and poor graft function in the posttransplant setting. We describe a case of a child with high-risk neuroblastoma, for whom plerixafor and eltrombopag were used as an effective and safe supportive therapy.

Advances in the understanding of poor graft function following allogeneic hematopoietic stem-cell transplantation

Poor graft function (PGF) following allogeneic hematopoietic stem-cell transplantation (allo-HSCT) is a life-threatening complication and is characterized by bilineage or trilineage blood cell deficiency and hypoplastic marrow with full chimerism. With the rapid development of allo-HSCT, especially haploidentical-HSCT, PGF has become a growing concern. The most common risk factors illustrated by recent studies include low dose of infused CD34+ cells, donor-specific antibody, cytomegalovirus infection, graft versus host disease (GVHD), iron overload and splenomegaly, among others. Because of the poor prognosis of PGF, it is crucial to uncover the underlying mechanism, which remains elusive. Recent studies have suggested that the bone marrow microenvironment may play an important role in the pathogenesis of PGF. Deficiency and dysfunction of endothelial cells and mesenchymal stem cells, elevated reactive oxygen species (ROS) levels, and immune abnormalities are believed to contribute to PGF. In this review, we also discuss recent clinical trials that evaluate the safety and efficacy of new strategies in patients with PGF. CD34+-selected stem-cell boost (SCB) is effective with an acceptable incidence of GVHD, despite the need for a second donation. Alternative strategies including the applications of mesenchymal stem cells, N-acetyl-l-cysteine (NAC), and eltrombopag have shown favorable outcomes, but further large-scale studies are needed due to the small sample sizes of the recent clinical trials.

Eltrombopag treatment promotes platelet recovery and reduces platelet transfusion for patients with post-transplantation thrombocytopenia

Post-transplantation thrombocytopenia (PT) is a common and severe complication which usually leads to poor prognosis. Eltrombopag (EPAG), a novel oral thrombopoietin (TPO) receptor agonist, has shown promising effects in thrombocytopenia due to immune thrombocytopenic purpura (ITP) and refractory severe aplastic anemia (rSAA), while the effectiveness of EPAG for PT patients still needs to be evaluated. A total of 32 PT patients receiving EPAG were retrospectively analyzed between September 2017 and July 2019, including 15 patients with poor graft function (PGF) and 17 patients with secondary failure of platelet recovery (SFPR). To date, 21 (65.6%) patients achieved overall recovery (OR) and 14 (43.8%) patients achieved complete recovery (CR). Among responders, 18 (85.7%) patients discontinued or tapered the drug and 16 (76.2%) patients successfully maintained their best response. During the EPAG treatment, responders received much lower median platelet transfusion units than non-responders (11 vs. 95, P < 0.001). After a median follow-up time of 364 days (range, 24-842), the overall survival in these patients was 78.1% (100% for responders and 36.4% for non-responders, P < 0.001). In the univariate and multivariate analysis, PGF was identified as the independent risk factor for OR (P = 0.041, HR = 5.333). Megakaryocyte (Megk) amounts (P = 0.025, HR = 14.638) and splenomegaly (P = 0.042, HR = 11.278) were identified as independent risk factors for CR. Besides, PGF patients tended to take a longer time to achieve PR and CR than SFPR patients. In conclusion, our data suggest that EPAG can promote platelet recovery and reduce platelet transfusion in PT patients.

Eltrombopag: Role in Cytopenias Following Hematopoietic Stem Cell Transplantation

Eltrombopag is a small molecule oral agonist of the thrombopoietin receptor. Initially used for improving thrombocytopenia in chronic immune thrombocytopenia (ITP), it was later found to be efficacious in various other etiologies of thrombocytopenia as well as inherited marrow failure syndromes. Lately, it has been used for thrombocytopenia and poor graft function after allogeneic hematopoietic stem cell transplantation (HSCT) without any severe adverse events. Although prospective evidence of the efficacy is limited, there are increasing reports on the safety and efficacy with Eltrombopag in post HSCT thrombocytopenia and poor graft function. This provides an exciting opportunity for further research to evaluate both efficacy and cost-effectiveness of the use of Eltrombopag in this scenario. Here we review the current evidence on the indications for the use of Eltrombopag in the post allogeneic hematopoietic stem cell transplant setting.

The Thrombopoietin Receptor Agonist Eltrombopag Inhibits Human Cytomegalovirus Replication Via Iron Chelation

The thrombopoietin receptor agonist eltrombopag was successfully used against human cytomegalovirus (HCMV)-associated thrombocytopenia refractory to immunomodulatory and antiviral drugs. These effects were ascribed to the effects of eltrombopag on megakaryocytes. Here, we tested whether eltrombopag may also exert direct antiviral effects. Therapeutic eltrombopag concentrations inhibited HCMV replication in human fibroblasts and adult mesenchymal stem cells infected with six different virus strains and drug-resistant clinical isolates. Eltrombopag also synergistically increased the anti-HCMV activity of the mainstay drug ganciclovir. Time-of-addition experiments suggested that eltrombopag interfered with HCMV replication after virus entry. Eltrombopag was effective in thrombopoietin receptor-negative cells, and the addition of Fe³⁺ prevented the anti-HCMV effects, indicating that it inhibits HCMV replication via iron chelation. This may be of particular interest for the treatment of cytopenias after hematopoietic stem cell transplantation, as HCMV reactivation is a major reason for transplantation failure. Since therapeutic eltrombopag concentrations are effective against drug-resistant viruses, and synergistically increase the effects of ganciclovir, eltrombopag is also a drug-repurposing candidate for the treatment of therapy-refractory HCMV disease.

Granulocyte Colony-Stimulating Factor-Primed Unmanipulated Haploidentical Blood and Marrow Transplantation

Granulocyte colony-stimulating factor (G-CSF), a growth factor for neutrophils, has been successfully used for stem cell mobilization and T cell immune tolerance induction. The establishment of G-CSF-primed unmanipulated haploidentical blood and marrow transplantation (The Beijing Protocol) has achieved outcomes for the treatment of acute leukemia, myelodysplastic syndrome, and severe aplastic anemia with haploidentical allografts comparable to those of human leukocyte antigen (HLA)-matched sibling donor transplantation. Currently, G-CSF-mobilized bone marrow and/or peripheral blood stem cell sources have been widely used in unmanipulated haploidentical transplant settings. In this review, we summarize the roles of G-CSF in inducing T cell immune tolerance. We discuss the recent advances in the Beijing Protocol, mainly focusing on strategies that have been used to improve transplant outcomes in cases of poor graft function, virus infections, and relapse. The application of G-CSF-primed allografts in other haploidentical modalities is also discussed.

Thrombopoietin Receptor Agonists for Severe Thrombocytopenia after Allogeneic Stem Cell Transplantation: Experience of the Spanish Group of Hematopoietic Stem Cell Transplant

Persistent thrombocytopenia is a common complication after allogeneic hematopoietic stem cell transplantation (allo-SCT). Romiplostim and eltrombopag are the currently available thrombopoietin receptor agonists (TPO-RAs), and some studies with very small numbers of cases have reported their potential efficacy in the allo-SCT setting. The present retrospective study evaluated the safety and efficacy of TPO-RAs in 86 patients with persistent thrombocytopenia after allo-HSCT. Sixteen patients (19%) had isolated thrombocytopenia (PT), and 71 (82%) had secondary failure of platelet recovery (SFPR). TPO-RA therapy was started at a median of 127 days (range, 27 to 1177 days) after allo-SCT. The median initial and maximum administered doses were 50 mg/day (range, 25 to 150 mg/day) and 75 mg/day (range, 25 to 150 mg/day), respectively, for eltrombopag and 1 µg/kg (range, 1 to 7 µg/kg) and 5 µg/kg (range, 1 to 10 µg/kg), respectively, for romiplostin. The median platelet count before initiation of TPO-RA therapy was 14,000/µL (range, 1000 to 57,000/µL). Platelet recovery to ≥50,000/µL without transfusion support was achieved in 72% of patients at a median time of 66 days (range, 2 to 247 days). Eighty-one percent of the patients had a decreased number of megakaryocytes before treatment, showing a slower response to therapy (P = .011). The median duration of treatment was 62 days (range, 7 to 700 days). Grade 3-4 adverse events (hepatic and asthenia) were observed in only 2% of the patients. At last follow-up, 81% of patients had discontinued TPO-RAs and maintained response, and 71% were alive. To our knowledge, this is the largest series analyzing the use of TPO-RAs after allo-SCT reported to date. Our results support the efficacy and safety in this new setting. Further prospective trials are needed to increase the level of evidence and to identify predictors of response.