Real-world impact of primary immune thrombocytopenia and treatment with thrombopoietin receptor agonists on quality of life based on patient-reported experience: Results from a questionnaire conducted in Switzerland, Austria, and Belgium

Aims of the study

Thrombopoietin receptor agonists (TPO-RAs) are approved for immune thrombocytopenia (ITP), but their impact on health-related quality of life (HRQoL) remains poorly investigated in clinical practice. This observational study aimed to gain insight into real-world patient-reported experiences of the burden of ITP and TPO-RAs.

Method

An online questionnaire of closed questions was used to collect views of patients with primary ITP from Switzerland, Austria, and Belgium, between September 2018 and April 2020.

Results

Of 46 patients who completed the questionnaire (total cohort), 41% were receiving TPO-RAs. A numerically higher proportion of patients reported being free from symptoms at the time of the questionnaire (54%) than at diagnosis (24%), irrespective of treatment type. Bleeding, the most frequently reported symptom at diagnosis (59%), was reduced at the time of the questionnaire (7%). Conversely, fatigue was reported by approximately 40% of patients at both diagnosis and the time of the questionnaire. Having a normal life and their disease under control was reported by 83% and 76%, respectively, but 41% were worried/anxious about their condition. Nearly 50% reported that ITP impaired their engagement in hobbies/sport or energy levels and 63% reported no impact on employment. When stratified by TPO-RA use, bleeding was better controlled in those receiving TPO-RAs than not (0% vs 11%). A numerically lower proportion receiving TPO-RAs than not reported worry/anxiety about their condition (16% vs 59%) and shifting from full-time to part-time employment (11% vs 22%). Similar proportions were satisfied with their therapy whether they were receiving TPO-RAs or not (89% vs 85%).

Conclusions

Many factors affect HRQoL in patients with ITP. Of patients receiving TPO-RAs, none experienced bleeding at the time of the questionnaire; they also showed a more positive perspective for some outcomes than those not using TPO-RAs. However, fatigue was not reduced by any treatment.

Eltrombopag improves refractory thrombocytopenia in patients with Sjögren's syndrome

INTRODUCTION

Eltrombopag, a kind of thrombopoietin (TPO) receptor agonist, plays the role on the megakaryocyte to activate the platelet production and rapidly increase the number of circulating platelets in patients with primary immune thrombocytopenia (ITP). Eltrombopag provides an opportunity for rapid tapering and/or cessation of corticosteroid therapy. However, it is not clear about the platelet response to Eltrombopag in ITP associated with Sjögren's Syndrome(SS).

METHODS

A retrospective research was conducted on the clinical course of three patients, each with ITP secondary to SS, and initially received therapy of corticosteroids or other immunomodulatory. They took this drug for bleeding diseases. Referring to the description, Eltrombopag was prescribed and adjusted with an initial dose of 25 mg daily, then weekly, then monthly according to the monitoring of platelet counts.

RESULTS

All patients maintained a satisfactory level of platelet counts (>100,000/mm3 for >2 years) following corticosteroid withdrawal. Meanwhile, Eltrombopag was well-tolerated, and there were no adverse effects, such as thrombotic events.

CONCLUSIONS

Eltrombopag is effective and safe for patients with ITP associated with SS during corticosteroid withdrawal. Thus it may be a crucial therapeutic strategy for reducing corticosteroid-related side effects in SS patients with ITP.

Changes in bone marrow and peripheral blood lymphocyte subset findings with onset of hepatitis-associated aplastic anemia

RATIONALE

Hepatitis-associated aplastic anemia (HAAA) is a rare illness that results in bone marrow failure following hepatitis development. The etiological agent remains unknown in most HAAA cases. However, clinical features of the disease and immunotherapy response indicate that immune-mediated factors play a central role in the pathogenesis of HAAA. Activation of cytotoxic T cells and increase in CD8 cells could exert cytotoxic effects on the myelopoietic cells in the bone marrow.

PATIENT CONCERNS

A 15-month-old boy was brought to our hospital with complaints of generalized petechiae and purpura observed a week prior to hospitalization. His liver was palpated 3 cm below the costal margin, platelet count was 0 × 104/μL, and alanine aminotransferase level was 1346 IU/L. A blood test indicated cytomegalovirus infection, and 3 bone marrow examinations revealed progressive HAAA. As the disease progressed to the 3rd, 6th, and 9th week after onset, CD4+ T cells were markedly decreased, CD8+ T cells were markedly increased, and the CD4/CD8 ratio was significantly decreased. The number of B cells and natural killer cells decreased with time, eventually reaching 0.0%.

DIAGNOSIS

HAAA.

INTERVENTIONS

Rabbit antithymocyte globulin and eltrombopag olamine (a thrombopoietin receptor agonist) were administered.

OUTCOMES

The patient's platelet count returned to normal, and bone marrow transplantation was avoided. The peripheral blood lymphocytes (PBLs) improved as the patient's general condition recovered.

LESSONS

This case demonstrates that HAAA induced by cytomegalovirus infection features decreasing CD4+ and increasing CD8+ PBLs as the bone marrow hypoplasia progresses. The PBLs return to their normal levels with the recovery from the disease. Our case findings thus support the involvement of immunological abnormality in HAAA.

Eltrombopag Added to Immunosuppression in Severe Aplastic Anemia

BACKGROUND

A single-group, phase 1-2 study indicated that eltrombopag improved the efficacy of standard immunosuppressive therapy that entailed horse antithymocyte globulin (ATG) plus cyclosporine in patients with severe aplastic anemia.

METHODS

In this prospective, investigator-led, open-label, multicenter, randomized, phase 3 trial, we compared the efficacy and safety of horse ATG plus cyclosporine with or without eltrombopag as front-line therapy in previously untreated patients with severe aplastic anemia. The primary end point was a hematologic complete response at 3 months.

RESULTS

Patients were assigned to receive immunosuppressive therapy (Group A, 101 patients) or immunosuppressive therapy plus eltrombopag (Group B, 96 patients). The percentage of patients who had a complete response at 3 months was 10% in Group A and 22% in Group B (odds ratio, 3.2; 95% confidence interval [CI], 1.3 to 7.8; P = 0.01). At 6 months, the overall response rate (the percentage of patients who had a complete or partial response) was 41% in Group A and 68% in Group B. The median times to the first response were 8.8 months (Group A) and 3.0 months (Group B). The incidence of severe adverse events was similar in the two groups. With a median follow-up of 24 months, a karyotypic abnormality that was classified as myelodysplastic syndrome developed in 1 patient (Group A) and 2 patients (Group B); event-free survival was 34% and 46%, respectively. Somatic mutations were detected in 29% (Group A) and 31% (Group Β) of the patients at baseline; these percentages increased to 66% and 55%, respectively, at 6 months, without affecting the hematologic response and 2-year outcome.

CONCLUSIONS

The addition of eltrombopag to standard immunosuppressive therapy improved the rate, rapidity, and strength of hematologic response among previously untreated patients with severe aplastic anemia, without additional toxic effects. (Funded by Novartis and others; RACE ClinicalTrials.gov number, NCT02099747; EudraCT number, 2014-000363-40.).

The efficacy and safety of thrombopoietin receptor agonists in patients with chronic liver disease undergoing elective procedures: a systematic review and meta-analysis

Thrombopoietin receptor agonists (TPO-RAs) can mitigate preprocedural thrombocytopenia in patients with chronic liver disease (CLD) however their effects on procedural outcomes is unclear. In this meta-analysis, we aimed to better define the efficacy, thrombotic risk and bleeding mitigation associated with the use of preoperative TPO-RAs in patients with CLD. We performed a systematic review and meta-analysis of randomized placebo-controlled clinical trials to assess the use of preprocedural TPO-RAs in patients with CLD, searching MEDLINE, EMBASE and the Cochrane library database. Six publications comprising eight randomized trials (1229 patients; 717 received TPO-RAs, 512 received placebo) and three unique TPO-RAs were retrieved. The majority of the included procedures were endoscopic. TPO-RAs were significantly more likely to result in a preoperative platelet count greater than 50 x 109/L (72.1% vs 15.6%, RR 4.8, 95% CI 3.6-6.4 p < .00001. NNT 1.8) and reduced the incidence of platelet transfusions (22.5% vs 67.8%, RR 0.33, 95% CI 0.3-0.4 p < .00001. NNT 2.2). Total periprocedural bleeding was decreased in patients who received TPO-RAs (11.6% vs 15.6%, RR 0.64, 95% CI 0.5-0.9 p = .01. NNT 24.7) and there was no increase in the rate of thrombosis (2.2% vs 1.8% RR 1.25, 95% CI 0.6-2.9 p = .60. NNH 211.1). In patients with CLD the use of preprocedural TPO-RAs resulted in significant increased platelet counts, and decreased the incidence of platelet transfusions as compared to placebo. TPO use likewise decreased the incidence of total periprocedural bleeding without increasing the rate of thrombosis.

[Systemic chemotherapy combined with thrombopoietin receptor agonist for the treatment of diffuse large B-cell lymphoma complicated with aplastic anemia]

Immunosuppressive therapies, including antithymocyte globulin and cyclosporine (CsA), are used for the treatment of aplastic anemia, but they reportedly cause lymphoproliferative diseases. Here, we report two cases of aplastic anemia in which diffuse large B-cell lymphoma developed during treatment with CsA. In both the cases, CsA was discontinued and combination therapy with R-CHOP (rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, and prednisolone) plus the thrombopoietin receptor agonist eltrombopag was initiated. Furthermore, supportive care, including blood transfusion and granulocyte colony-stimulating factor, was provided. After six or eight courses of R-CHOP therapy, a complete metabolic response was achieved without serious adverse events. These cases illustrate the safety of combining R-CHOP with eltrombopag therapy in patients at a high risk of severe pancytopenia.

Effects of Lusutrombopag on Post-invasive Procedural Bleeding in Thrombocytopenic Patients with Chronic Liver Disease

INTRODUCTION

Thrombocytopenia can increase the bleeding risk in patients with chronic liver disease (CLD) undergoing invasive procedures. Prophylactic platelet transfusion (PT) is often performed to increase platelet counts in patients with CLD undergoing invasive procedures to prevent bleeding. Lusutrombopag, a small-molecule thrombopoietin receptor agonist, is expected to be an alternative therapy to prophylactic PT. This study aimed to compare the effects between lusutrombopag and PT.

METHODS

Data were obtained from a Japanese administrative database (April 2008-May 2019). Patients aged ≥ 18 years who underwent planned invasive procedures after the first CLD diagnosis and were observed for ≥ 30 days prior to invasive procedures were considered eligible. Patients who underwent planned invasive procedures with lusutrombopag prescription at 5-30 days before the procedure were categorized as the lusutrombopag group, whereas those who received PT at 1 day before and/or on the same day as the procedure, without lusutrombopag prescription, were classified as the PT group. Outcomes, including bleeding frequency during hospitalization and average medical costs (costs for prophylactic treatment and total costs between the day of the invasive procedure and 30 days after the invasive procedure), were compared between the groups after matching.

RESULTS

Among 738,878 patients with CLD, 379 cases for each group were identified after matching. The incidence of bleeding events was lower in the lusutrombopag group than in the PT group (3.7% vs. 8.2%, p < 0.001). Average medical costs were lower in the lusutrombopag group than in the PT group ($6667 as of August 2021 vs. $7170, p = 0.011).

CONCLUSION

Lusutrombopag is suggested to be effective as a prophylactic treatment for bleeding prevention in patients with CLD undergoing planned invasive procedures.

Targeted therapies for immune thrombocytopenic purpura: a meta-analysis of randomized controlled trials

Several targeted therapies have been approved in recent years for second-line treatment of immune thrombocytopenic purpura (ITP), providing an alternative to rituximab and splenectomy. The extent to which these drugs reduce bleeding risk has not been well defined. Targeted therapies recently approved for the treatment of ITP in adults were identified through a search of recently published professional guidelines. Randomized controlled trials (RCTs) supporting regulatory approval were identified through a search of drug labels on FDA@gov. Odds ratios (ORs) and associated 95% confidence intervals (CIs) were computed for pre-specified efficacy outcomes including platelet recovery to ≥ 50,000/µL, major and minor bleeding events, and survival. ORs for all adverse events were also computed. Four targeted therapies were identified, including three thrombopoietin receptor agonists and one tyrosine kinase inhibitor. Six RCTs, comprising 752 patients, were included in the meta-analysis. More patients treated with targeted therapies for ITP as compared to placebo achieved platelet counts over ≥ 50,000/µL (OR 8.29, 95% CI 5.59-12.29). Compared to placebo, targeted therapies for ITP were associated with significantly lower odds for major bleeding (OR 0.43, 95% CI 0.21-0.91), minor bleeding (OR 0.66, 95% CI 0.45-0.97), and with numerically lower mortality rates (OR 0.24, 95% CI 0.05-1.07). The odds for adverse events were comparable between the two arms (OR 1.43 95% CI 0.76-2.67). Compared to placebo, targeted therapies for ITP increase platelet counts, decrease bleeding events, and show a trend towards lower mortality, without increased toxicity. These findings support their use as a second-line ITP treatment.

Eltrombopag treatment for severe immune thrombocytopenia during pregnancy: a case report

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia (platelet count <100 × 109/l) in the absence of other causes or disorders associated. The incidence of ITP in pregnancy is one to two cases per 1000 gestations. ITP could be diagnosed before or during pregnancy; sometimes a relapse of a previously diagnosed ITP can occur. Intravenous immune globulins (IVIg) and corticosteroids are the standard frontline therapy because of their well known safety profile either for the mother or for the neonate. Treatments for refractory patients are limited by potential fetal risk. We report the case of a patient with ITP along pregnancy, refractory to corticosteroids and IVIg, successfully treated with, the thrombopoietin receptor agonist (TPO-RA) eltrombopag. Patient received this compound for almost the whole pregnancy and in particular for the whole first trimester, without any complication for the mother and the neonate. Although transient administration of TPO-RAs in pregnancy seems to be well tolerated, their use during the whole gestation is still controversial; this is the reason of the description of this case, which did not show any complications, and thus it could add useful information on this field.

Immune thrombocytopenia: options and new perspectives

Immune thrombocytopenia is a haematological, autoimmune disorder characterized by elevated platelet demolition due to the presence of antiplatelet autoantibodies derived from B cells and to an irregular, deficient process of platelets production in bone marrow. In this review, after a brief presentation of 'old' strategies used nowadays yet, we focused on new drugs used in the treatment of immune thrombocytopenia and their mechanism of action and posology, basing on the last scientific literature. The observation that CoViD-19 can be associated with immune thrombocytopenia is also put in evidence. Particular attention will be dedicated on the concept that the ideal treatment should represent a solution not only for the failure of normal processes of production and survival of platelets, but also it should improve quality of life of patients, with minimum adverse events. Anyway, despite enormous advances of the last years, further investigations are necessary in order to define scrupulously long-term efficacy of new molecules proposed.

Romiplostim in children with newly diagnosed or persistent primary immune thrombocytopenia

Immune thrombocytopenia (ITP) is a disease of heterogenous origin characterized by low platelet counts and an increased bleeding tendency. Three disease phases have been described: newly diagnosed (≤ 3 months after diagnosis), persistent (> 3-12 months after diagnosis), and chronic (> 12 months after diagnosis). The majority of children with ITP have short-lived disease and will not need treatment. For children with newly diagnosed ITP, who have increased bleeding symptoms, short courses of steroids are recommended. In children who do not respond to first-line treatment or who become steroid dependent, thrombopoietin receptor agonists (TPO-RAs) are recommended because of their efficacy and safety profiles. In this narrative review, we evaluate the available evidence on the use of the TPO-RA romiplostim to treat children with newly diagnosed or persistent ITP and identify data from five clinical trials, five real-world studies, and a case report. While the data are more limited for children with newly diagnosed ITP than for persistent ITP, the collective body of evidence suggests that romiplostim is efficacious in increasing platelet counts in children with newly diagnosed or persistent ITP and may result in long-lasting treatment-free responses in some patients. Furthermore, romiplostim was found to be well tolerated in the identified studies. Collectively, the data suggest that earlier treatment with romiplostim may help children to avoid the side effects associated with corticosteroid use and reduce the need for subsequent treatment.

Role of Thrombopoietin Receptor Agonists in Inherited Thrombocytopenia

In the last decade, improvements in genetic testing have revolutionized the molecular diagnosis of inherited thrombocytopenias (ITs), increasing the spectrum of knowledge of these rare, complex and heterogeneous disorders. In contrast, the therapeutic management of ITs has not evolved in the same way. Platelet transfusions have been the gold standard treatment for a long time. Thrombopoietin receptor agonists (TPO-RA) were approved for immune thrombocytopenia (ITP) ten years ago and there is evidence for the use of TPO-RA not only in other forms of ITP, but also in ITs. We have reviewed in the literature the existing evidence on the role of TPO-RAs in ITs from 2010 to February 2021. A total of 24 articles have been included, 4 clinical trials, 3 case series and 17 case reports. A total of 126 patients with ITs have received TPO-RA. The main diagnoses were Wiskott–Aldrich syndrome, MYH9-related disorder and ANKRD26-related thrombocytopenia. Most patients were enrolled in clinical trials and were treated for short periods of time with TPO-RA as bridging therapies towards surgical interventions, or other specific approaches, such as hematopoietic stem cell transplantation. Here, we have carried out an updated and comprehensive review about the efficacy and safety of TPO-RA in ITs.

Tapering and Discontinuation of Thrombopoietin Receptor Agonist Therapy in Patients with Immune Thrombocytopenia: Results from a Modified Delphi Panel

BACKGROUND

Recent evidence suggests that in patients with immune thrombocytopenia (ITP) with a stable response on thrombopoietin receptor agonists, treatment may be tapered and/or discontinued.

OBJECTIVES

The objective of this study was to provide a guide for tapering and discontinuation of TPO-RA therapy in patients with ITP, based on hematologist survey results, existing evidence, and expert consensus.

PATIENTS/METHODS

UK hematologists completed a survey to characterize self-reported practice patterns related to TPO-RA tapering and discontinuation in patients with ITP. Using a modified Delphi panel approach, ITP experts developed consensus statements regarding the use of TPO-RA tapering and discontinuation.

RESULTS

Survey respondents estimated that 30-34% of their patients were suitable for tapering or discontinuation and that 29-35% of these patients required treatment re-initiation after an average treatment-free interval of 86-106 days. No clear predictors of patient suitability or response to tapering or discontinuation were identified. The ITP expert consensus was that approximately 30% of patients are eligible for tapering and discontinuation, which may be considered after 6-12 months for patients demonstrating an adequate treatment response (platelet count >50,000/µL at ≥75% of assessments in the preceding 6 months). Treatment re-initiation may be considered if the platelet count decreases or if the patient becomes symptomatic. Individual differences need to be taken into account when considering TPO-RA tapering or discontinuation.

CONCLUSIONS

Tapering and discontinuation of TPO-RA therapy may be considered for certain patients with ITP. Further study is needed to better predict patients likely to achieve sustained off-treatment responses after tapering and discontinuation.

Establishment of a novel mesenchymal stem cell-based regimen for chronic myeloid leukemia differentiation therapy

Chronic myeloid leukemia (CML) is characterized by the accumulation of malignant and immature white blood cells which spread to the peripheral blood and other tissues/organs. Despite the fact that current tyrosine kinase inhibitors (TKIs) are capable of achieving the complete remission by reducing the tumor burden, severe adverse effects often occur in CML patients treated with TKIs. The differentiation therapy exhibits therapeutic potential to improve cure rates in leukemia, as evidenced by the striking success of all-trans-retinoic acid in acute promyelocytic leukemia treatment. However, there is still a lack of efficient differentiation therapy strategy in CML. Here we showed that MPL, which encodes the thrombopoietin receptor driving the development of hematopoietic stem/progenitor cells, decreased along with the progression of CML. We first elucidated that MPL signaling blockade impeded the megakaryocytic differentiation and contributed to the progression of CML. While allogeneic human umbilical cord-derived mesenchymal stem cells (UC-MSCs) treatment efficiently promoted megakaryocytic lineage differentiation of CML cells through restoring the MPL expression and activating MPL signaling. UC-MSCs in combination with eltrombopag, a non-peptide MPL agonist, further activated JAK/STAT and MAPK signaling pathways through MPL and exerted a synergetic effect on enhancing CML cell differentiation. The established combinational treatment not only markedly reduced the CML burden but also significantly eliminated CML cells in a xenograft CML model. We provided a new molecular insight of thrombopoietin (TPO) and MPL signaling in MSCs-mediated megakaryocytic differentiation of CML cells. Furthermore, a novel anti-CML treatment regimen that uses the combination of UC-MSCs and eltrombopag shows therapeutic potential to overcome the differentiation blockade in CML.

[Thrombopoietin receptor agonists for pediatric refractory chronic immune thrombocytopenia]

Various treatments have been used to treat chronic immune thrombocytopenic purpura in children; however, none of it has been established as the standard of care. The administration of thrombopoietin receptor agonists (TPO-RAs) has been approved as a new treatment option in Japan. In this case series, TPO-RAs were administered to 16 patients (eltrombopag, n=9; romiplostim, n=7). Excluding the data of two patients who underwent splenectomy immediately after starting treatment with these medicines, platelet counts increased to ≥50,000/µl in seven patients. The adverse events recorded were grade 2 liver dysfunction (n=1), according to the common terminology criteria for adverse events version 4, and myelofibrosis (classified as MF1 or mild reticulin fibrosis), as observed on bone marrow biopsy (n=2). We continued the administration of TPO-RAs at the same dose in these patients because the complications they experienced were mild. The risk of adverse events associated with long-term use of TPO-RAs in this pediatric population remains unclear, and a prospective evaluation is needed.

Romiplostim is effective for eltrombopag-refractory aplastic anemia: results of a retrospective study

Eltrombopag (EPAG) and romiplostim (ROM), thrombopoietin receptor-agonists with demonstrated efficacy against aplastic anemia (AA) in prospective controlled studies, were authorized in Japan for use in adults with aplastic anemia in 2017 and 2019, respectively. So far, no data are available on the potential contribution of switching from ROM to EPAG or vice versa in terms of efficacy or tolerance. Efficacies and tolerance profiles of ten patients, who failed to respond to the maximum dose of EPAG and then switched to ROM, were evaluated. All ten patients received a maximum dose of ROM (20 μg/kg/week). At a median follow-up of twelve months, seven of ten patients (70%) had achieved either neutrophil, erythroid, or platelet response, including one complete response. No patients showed platelet count fluctuations that were reported during ROM treatment for immune thrombocytopenia. In univariate analysis of the relationship between efficacy and demographics, the response had a correlation with neither factors. None of the patients stopped the ROM treatment because of adverse events. Although a larger number of patients and a longer follow-up period are needed to confirm our findings, our results show the efficacy of ROM in patients with EPAG-refractory AA.

A novel sponge-derived protein thrombocorticin is a new agonist for thrombopoietin receptor

We screened 868 marine extracts in search of hematopoietic molecules resulted in findings of several extracts that proliferated Ba/F3-HuMpl cells but not the cells expressed with other hematopoietic cytokine receptors, EPO and G-CSF. Separation of the most potent extract of a Micronesian sponge Corticium sp., guided by the cell proliferation assay using Ba/F3-HuMpl cells resulted in an isolation of thrombocorticin (ThC), a novel 14 kDa protein as an active principal. ThC displayed concentration-dependent proliferation of Ba/F3-HuMpl cells, and had a stronger activity than that of eltrombopag, a small molecule drug used to treat thrombocytopenia. ThC induced phosphorylation of STAT5, suggesting that it activates Jak/STAT pathway as in the case of TPO. These results together indicated that ThC is a specific agonist for c-Mpl, although the size and shape differs largely from TPO. Here we present isolation, characterization and biological activity of ThC.

New Small Molecule Drugs for Thrombocytopenia: Chemical, Pharmacological, and Therapeutic Use Considerations

This review provides details about three small molecules that were recently approved by the FDA for the treatment of thrombocytopenia. The new treatments include lusutrombopag, avatrombopag, and fostamatinib. The first two drugs are orally active thrombopoietin receptor (TPO-R) agonists which are FDA-approved for the treatment of thrombocytopenia in adult patients with chronic liver disease who are scheduled to undergo a procedure. Fostamatinib is orally active prodrug that, after activation, becomes spleen tyrosine kinase (SYK) inhibitor. Fostamatinib is currently used to treat chronic and refractory immune thrombocytopenia in patients who have had insufficient response to previous treatment. Chemical structures, available dosage forms, recommended dosing, pharmacokinetics, results of toxicity studies in animals, most frequent adverse effects, significant outcomes of the corresponding clinical trials, and their use in specific patient populations are thoroughly described. Described also is a comparative summary of the different aspects of five currently available therapies targeting TPO-R or SYK for the treatment of thrombocytopenia.

Thrombopoietin receptor agonists: ten years later

The two thrombopoietin receptor agonists (TPO-RA), eltrombopag and romiplostim, were licensed in the US for treatment of immune thrombocytopenia (ITP) in 2008 and, since then, their use has progressively increased around the world; they are currently used in more than 100 countries. The six largest randomized controlled trials conducted in ITP have used one of these two agents. All studies have demonstrated a platelet response rate between 50-90%, depending on the criteria used, with good safety and tolerability. TPO-RA were shown to be effective in reducing bleeding and the need for concomitant or rescue medication. Many other investigations of their mechanism of effect, prospective and retrospective trials, and studies focusing on toxicity have been performed widening our knowledge of these two agents. Initial concerns on issues such as myelofibrosis have not been confirmed. Only a small number of patients develop moderate-severe reticulin fibrosis and/or collagen fibrosis; however, these are usually reversed after discontinuation of TPO-RA. Studies indicate, however, that TPO-RA may increase the risk of venous thromboembolism. Both TPO-RA are currently approved in patients with chronic ITP aged >1-year who are refractory to at least one other treatment. Eltrombopag has acquired two additional indications: severe aplastic anemia refractory to first-line treatment and hepatitis C patients undergoing treatment with interferon-ribavirin. Despite these wide-ranging studies, important questions still need to be answered. This summary review on TPO-RA will summarize what is known regarding efficacy in ITP, evaluate safety concerns in more depth, and focus on the questions that remain.

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.

Real-life experience of lusutrombopag for cirrhotic patients with low platelet counts being prepared for invasive procedures

BACKGROUND AND AIMS

The present study aimed to report our real-life experience of the TPO receptor agonist lusutrombopag for cirrhotic patients with low platelet counts.

METHODS

We studied platelet counts in 1,760 cirrhotic patients undergoing invasive procedures at our hospital between January 2014 and December 2017. In addition, we studied 25 patients who were administered lusutrombopag before invasive procedures between June 2017 and January 2018. Effectiveness of lusutrombopag to raise platelet counts and to avoid transfusion and treatment-related adverse events were analyzed.

RESULTS

In 1,760 cirrhotic patients without lusutrombopag prior to invasive procedures, proportion of patients whose platelet counts <50,000/μL and needed platelet transfusions were 66% (n = 27/41) for radiofrequency ablation, 43% (n = 21/49) for transarterial chemoembolization, and 55% (n = 21/38) for endoscopic injection sclerotherapy / endoscopic variceal ligation, respectively. In 25 cirrhotic patients treated by lusutrombopag prior to the invasive procedures, platelet counts significantly increased compared with baseline (82,000 ± 26,000 vs. 41,000 ± 11,000/μL) (p < 0.01). Out of 25 patients, only 4 patients (16%) needed platelet transfusion before the invasive procedures. The proportion of patients with low platelet count and who needed platelet transfusions was significantly low in patients treated with lusutrombopag compared to those not treated with lusutrombopag (16% (4/25) vs. 54% (69/128), p = 0.001). Platelet counts after lusutrombopag treatment and prior to invasive procedures were lower in patients with a baseline platelet count ≤30,000/μL (n = 8) compared with those with a baseline platelet count >30,000/μL (n = 17) (50,000 ± 20,000 vs 86,000 ± 26,000/μL, p = 0.002). Patients with a baseline platelet count ≤30,000/μL with spleen index (calculated by multiplying the transverse diameter by the vertical diameter measured by ultrasonography) ≥40 cm2 (n = 3) had a lower response rate to lusutrombopag compared to those with spleen index <40 cm2 (n = 5) (0% vs. 100%, p = 0.02). Hemorrhagic complication was not observed. Recurrence of portal thrombosis was observed and thrombolysis therapy was required in one patient who had prior history of thrombosis.

CONCLUSIONS

Lusutrombopag is an effective and safe drug for thrombocytopenia in cirrhotic patients, and can reduce the frequency of platelet transfusions.

Relationship between response to lusutrombopag and splenic volume

AIM

To assess the correlation between the efficacy of lusutrombopag and clinical characteristics in patients with chronic liver disease.

METHODS

In this retrospective, multicenter study, which conducted at four locations in Japan, 50 thrombocytopenic patients with chronic liver disease were enrolled. All patients received oral lusutrombopag (3.0 mg/d for 7 d) for chronic liver disease. We assessed the increase in platelet count after the trial drug administration. A treatment response was defined as a platelet count ≥ 5 × 104/μL and an increased platelet count ≥ 2 × 104/μL from baseline after drug administration. We evaluated the response to lusutrombopag compared to baseline clinical characteristics in patients with chronic liver disease.

RESULTS

The numbers of responders and non-responders were 40 (80.0%) and 10 (20.0%), respectively. The patients were divided into a responder and non-responder group, and we added factors that may correspond to successful treatment with lusutrombopag. Splenic volume and body weight were lower in the responder group than in the non-responder group. White blood cell count and hemoglobin level were higher in responders compared with non-responders. Using a logistic regression model to assess the relationship between response to lusutrombopag and clinical characteristics, multivariate analysis confirmed that splenic volume was an independent factor that predicted the response of platelet counts (P = 0.025; odds ratio = 11.2; 95% confidence interval: 1.354-103.0). Splenic volume negatively correlated to changes in platelet count (r = -0.524, P = 0.001).

CONCLUSION

Splenic volume influences the change in platelet counts after administration of lusutrombopag in patients with chronic liver disease.

Management of immune thrombocytopenia in elderly patients

Despite the improvement in understanding its pathogenesis and the introduction of novel treatment options, the management of primary immune thrombocytopenia (ITP) still remains challenging. Considering its increased incidence with aging and prolonged life-expectancy, ITP is often diagnosed in elderly patients, a subset that deserves some special precautions. Ensure the diagnosis is a crucial step, and carefully attention must be given in excluding other causes of thrombocytopenia, especially among older people that frequently suffer from many comorbidities. When it comes to treatment decision, it is worth keeping into account that the elderly have an increased risk of bleeding, thrombosis and infections, that they often require many concomitant therapies, including antiplatelet or anticoagulant agents, and that treatment-related toxicities are often increased and sometimes more dangerous that the disease itself. There are not dedicated guidelines, and only few specific studies. Steroids with or without IVIG remain the first-line treatment. Splenectomy is less effective than in youngers and burdened by an increased thrombotic and infectious risk. Rituximab is a good option in non-immunocompromised patients, but long-term remissions are few. Eltrombopag and romiplostim have a good safety and efficacy profile, and have become a prominent drug in this subset, even if they are associated with a possible increased risk of thrombosis, and long-term toxicity is unknown. Other drugs, such as dapsone and danazol, have a well-known efficacy and safety profile, and still represent a valid option among elderly patients.