Remission and platelet responses with romiplostim in primary immune thrombocytopenia: final results from a phase 2 study

Platelet response to romiplostim amongst patients with newly diagnosed, persistent, and chronic immune thrombocytopenia in routine clinical practice in Denmark, Sweden, and Norway

Patient characteristics and platelet responses at romiplostim initiation according to the duration of immune thrombocytopenia (ITP) are poorly understood. Amongst romiplostim-exposed adults with ITP lasting ≥6 months during 2009-2018 in Denmark, Sweden, and Norway, we examined characteristics at romiplostim initiation, romiplostim dosage, and durable platelet response (≥75% of measurements ≥50 × 109/L at 14-24 weeks) for subcohorts with newly diagnosed (duration <3 months), persistent (3-12 months), or chronic (>12 months) ITP initiating romiplostim. The 285 romiplostim initiators comprised 81 (28%) with newly diagnosed, 47 (16%) with persistent, and 157 (55%) with chronic ITP. More patients with newly diagnosed ITP than longer ITP duration, had low comorbidity levels, two or more prior ITP therapies, and previous bleeding requiring hospitalisation. The median romiplostim doses were similar across subcohorts. During treatment, median platelet counts were similar across subcohorts (75-76 × 109/L), and the durable platelet response was 64.6%, 52.9%, and 52.7% for newly diagnosed, persistent, and chronic ITP, respectively. After treatment cessation, the median platelet count was 138 × 109/L, 68 × 109/L, and 71 × 109/L, respectively. In conclusion, newly diagnosed patients, compared with romiplostim initiators with longer disease duration, had more severe ITP, higher frequency of durable platelet response, and higher median platelet count after cessation.

Platelet-derived TGF-β1 induces functional reprogramming of myeloid-derived suppressor cells in immune thrombocytopenia

ABSTRACT

Platelet α-granules are rich in transforming growth factor β1 (TGF-β1), which is associated with myeloid-derived suppressor cell (MDSC) biology. Responders to thrombopoietin receptor agonists (TPO-RAs) revealed a parallel increase in the number of both platelets and MDSCs. Here, anti-CD61 immune-sensitized splenocytes were transferred into severe combined immunodeficient mice to establish an active murine model of immune thrombocytopenia (ITP). Subsequently, we demonstrated that TPO-RAs augmented the inhibitory activities of MDSCs by arresting plasma cells differentiation, reducing Fas ligand expression on cytotoxic T cells, and rebalancing T-cell subsets. Mechanistically, transcriptome analysis confirmed the participation of TGF-β/Smad pathways in TPO-RA-corrected MDSCs, which was offset by Smad2/3 knockdown. In platelet TGF-β1-deficient mice, TPO-RA-induced amplification and enhanced suppressive capacity of MDSCs was waived. Furthermore, our retrospective data revealed that patients with ITP achieving complete platelet response showed superior long-term outcomes compared with those who only reach partial response. In conclusion, we demonstrate that platelet TGF-β1 induces the expansion and functional reprogramming of MDSCs via the TGF-β/Smad pathway. These data indicate that platelet recovery not only serves as an end point of treatment response but also paves the way for immune homeostasis in immune-mediated thrombocytopenia.

Update on the Use of Thrombopoietin-Receptor Agonists in Pediatrics

This review summarizes the rationale and current data on the use of thrombopoietin receptor agonists (TPO-RAs) for treating severe thrombocytopenia in infants, children, and adolescents. It focuses on substances that have been approved by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) for pediatric patients. Romiplostim and eltrombopag are already established as second-line treatment for persistent or chronic immune thrombocytopenia (ITP). As in adults, TPO-RAs are currently also evaluated in severe aplastic anemia (SAA), chemotherapy-induced thrombocytopenia (CIT), myelodysplastic syndromes (MDS), and poor engraftment after hematopoietic stem cell transplantation in pediatric and adolescent patients. Moreover, studies on the implication of TPO-RA in treating rare inherited thrombocytopenias, such as Wiskott-Aldrich syndrome (WAS), congenital amegakaryocytic thrombocytopenia (CAMT), or MYH9-associated thrombocytopenia, deserve future attention. Current developments include testing of avatrombopag and lusutrombopag that are approved for the treatment of thrombocytopenia associated with chronic liver disease (CLD) in adult patients. In pediatric and adolescent medicine, we expect in the near future a broader use of TPO-RAs as first-line treatment in primary ITP, thereby considering immunomodulatory effects that increase the rate of sustained remission off-treatment, and a selective use in rare inherited thrombocytopenias based on current clinical trials.

Immune thrombocytopenia: Pathophysiology and impacts of Romiplostim treatment

Immune thrombocytopenia (ITP) is an autoimmune bleeding disease caused by immune-mediated platelet destruction and decreased platelet production. ITP is characterized by an isolated thrombocytopenia (<100 × 109/L) and increased risk of bleeding. The disease has a complex pathophysiology wherein immune tolerance breakdown leads to platelet and megakaryocyte destruction. Therapeutics such as corticosteroids, intravenous immunoglobulins (IVIg), rituximab, and thrombopoietin receptor agonists (TPO-RAs) aim to increase platelet counts to prevent hemorrhage and increase quality of life. TPO-RAs act via stimulation of TPO receptors on megakaryocytes to directly stimulate platelet production. Romiplostim is a TPO-RA that has become a mainstay in the treatment of ITP. Treatment significantly increases megakaryocyte maturation and growth leading to improved platelet production and it has recently been shown to have additional immunomodulatory effects in treated patients. This review will highlight the complex pathophysiology of ITP and discuss the usage of Romiplostim in ITP and its ability to potentially immunomodulate autoimmunity.

The Challenge for a Correct Diagnosis of Refractory Thrombocytopenia: ITP or MDS with Isolated Thrombocytopenia?

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by isolated thrombocytopenia. It is diagnosed in patients with a platelet count below 100,000 per cubic millimeter in whom other causes of thrombocytopenia have been ruled out, and its diagnosis is generally one of exclusion. Clinical manifestations of patients may vary from asymptomatic disease to mild mucocutaneous or life-threatening bleeding. Glucocorticoids are used as first-line treatment for ITP, while other second-line medications, mainly thrombopoietin-receptor agonists (TPO-RA) and rituximab, are given to patients in whom ITP does not remit, or relapses soon after glucocorticoid treatment. Refractoriness of ITP strongly questions its diagnosis and necessitates a thorough clinical and laboratory work-up to decide whether that is the case of refractory ITP or a misdiagnosis. The aim of this review is to summarize the conditions associated with isolated thrombocytopenia and highlight the characteristics of confusing cases. Even though the case of a myelodysplastic syndrome presented with isolated thrombocytopenia (MDS-IT) is relatively rare and not well-established in the literature, it constitutes one of the most predominant misdiagnoses of refractory ITP. MDS-IT patients are thought to present with multilineage dysplasia, normal karyotype and low risk prognostic score, based on IPSS-R. It has been shown that a significant proportion of MDS-IT patients are misdiagnosed as having the more common ITP. Therefore, it is crucial that in confusing cases of persistent thrombocytopenia a detailed diagnostic work-up is applied-including evaluation of peripheral-blood smear, bone marrow examination and cytogenetic testing-to avoid unnecessary therapy delay.

Long-term eltrombopag in children with chronic immune thrombocytopenia: A single-centre extended real-life observational study in China

We have previously confirmed the efficacy and safety of eltrombopag (ELT) in children with chronic immune thrombocytopenia (cITP). However, data on both long-term exposure and early use of TPO-RAs are lacking, so further 'field-practice' evidence on treatment is required. Here, we report the long-term follow-up results (between September 2018 and June 2023) of our previous study. The main objective of this study was to retrospectively review our large institutional experience with ITP patients previously enrolled in our paediatric cITP study. We had more than 3 years of follow-up by June 2023 for treatment patterns and outcomes. A total of 65 patients (28 males) were enrolled, with a median age at ELT initiation of 6.34 (range 1.65, 14.13) years and a follow-up of 47.07 (36.00, 57.00) months, with 40.36 (10.53, 56.83) months of ELT therapy at the time of analysis. In total, 29.23% (19/65) of patients discontinued ELT due to stable response, and 18.46% (12/65) of patients switched to other ITP therapies due to loss of response (LOR) after 19.13 (14.53, 26.37) months. Of the 19 patients who discontinued ELT due to a stable response, 24.62% (16/65) achieved a 12 m sustained response off-treatment (SRoT); the last recorded platelet count ranged from 56 to 166 × 109 /L (median 107 × 109/L); and 4.62% (3/65) patients relapsed at 5, 6 and 9 months after discontinuation. Of the 12 patients who LOR to ELT after 19.13 (14.53, 26.37) months of therapy, four switched to avatrombopag, three switched to hetrombopag, two switched to traditional Chinese medicine (TCM), one underwent splenectomy and two received additional prednisolone under ELT treatment. Thirty-four patients who tapered and maintained a durable response. The patients with LOR and the patients with tapering were compared; the platelet count at the start of ELT is lower, and the time to response is longer in the patients with LOR. The platelet count at the start of ELT and the time to response may be the predictive factors for LOR during ELT treatment. We report more than 3 years of long-term clinical data on children with cITP using ELT. These data do not raise any new safety concerns regarding the long-term use of ELT in children with cITP.

Thrombopoietin Receptor Agonists and Other Second-Line Therapies for Immune Thrombocytopenia: A Narrative Review With a Focus on Drug Access in Canada

INTRODUCTION

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by low platelet counts and increased risk of bleeding. After corticosteroids with or without intravenous immune globulin (first-line treatment), second-line treatment options include rituximab, splenectomy, thrombopoietin receptor agonists (TPO-RAs), and fostamatinib. In Canada, the choice of second-line therapy is influenced by access to medications. The goals of this narrative review are to 1) summarize the evidence for the use of TPO-RAs and other second-line therapies in ITP and 2) highlight differences in public funding criteria for TPO-RAs across provinces and territories in Canada.

METHODS

We conducted a literature review of second-line therapies for ITP. We solicited information on public funding programs for TPO-RAs in Canada from health care providers, pharmacists, and provincial ministries of health.

RESULTS

Head-to-head trials involving TPO-RAs, rituximab, splenectomy, and fostamatinib are lacking. There is substantial evidence of effect for TPO-RAs in improving platelet count levels, health-related quality of life, bleeding, and fatigue from placebo-controlled trials and observational studies; however, access to TPO-RAs through provincial funding programs in Canada is variable. Splenectomy failure is a prerequisite for the funding of TPO-RAs in Ontario, Manitoba, and Saskatchewan, but not in Alberta or Quebec. Other provinces either do not have access to public funding or funding is provided on a case-by-case basis.

DISCUSSION

TPO-RAs are effective second-line therapies for the treatment of ITP; however, access is variable across Canada, which results in health disparities and poor uptake of international treatment guidelines.

Avatrombopag for adults with early versus chronic immune thrombocytopenia

Avatrombopag is a newer thrombopoietin receptor agonist (TPO-RA) currently approved to treat chronic ITP (duration >12 months). No studies have yet evaluated the safety and effectiveness of avatrombopag in newly diagnosed ITP (duration <3 months) or persistent ITP (duration 3-12 months), and so its use in these populations is presently off-label worldwide. We hypothesize that avatrombopag has similar safety and effectiveness irrespective of ITP disease phase. To evaluate this, we performed a multicenter observational cohort study of adults with ITP treated with avatrombopag, comparing patient outcomes by disease phase (newly diagnosed/persistent versus chronic). Seventy-five patients were included, 23 with newly diagnosed/persistent ITP (17.7 patient-years of avatrombopag treatment) and 52 with chronic ITP (65.3 patient-years of avatrombopag treatment). On avatrombopag, 91% of newly diagnosed/persistent patients versus 96% of chronic patients (p = .58) achieved a platelet response (≥50 × 109 /L) and 86% versus 81% of patients (p = .78) achieved a complete response (≥100 × 109 /L). Median platelet counts on avatrombopag were similar between the two groups (165 × 109 /L vs. 129 × 109 /L, p = .57). Response durability was high and similar in both groups. No patients in the newly diagnosed/persistent group had a major bleeding event, thromboembolic event or avatrombopag discontinuation for adverse events, compared with 4, 1, and 2, respectively, in the chronic group. Thrombocytosis (platelets ≥400 × 109 /L) incidence was similar in the two groups. No other drug-related adverse events occurred in either group. Avatrombopag was safe and effective in patients with newly diagnosed and persistent ITP, with outcomes numerically, statistically, and clinically similar to patients receiving avatrombopag for chronic ITP.

Sustained response off-treatment in eltrombopag-treated adult patients with ITP who are refractory or relapsed after first-line steroids: Primary, final, and ad-hoc analyses of the Phase II TAPER trial

Immune thrombocytopenia (ITP) is characterized by reduced platelet count due to increased destruction and is categorized according to the time following diagnosis (newly diagnosed, persistent, chronic). First-line corticosteroid therapy is associated with transient response, high relapse rates, and considerable toxicity. TAPER (NCT03524612) is a Phase II, prospective, single-arm trial investigating whether eltrombopag can induce a sustained response off-treatment (SRoT) in adult patients with ITP after first-line corticosteroid failure. This study defines SRoT as an off-treatment period wherein platelet count remains above 30 × 109 /L in the absence of bleeding or rescue therapy. The primary endpoint was the proportion of patients who achieved SRoT until Month 12, which was 30.5% (n = 32/105; p < .0001 testing hypothesis H1: proportion >15%) following eltrombopag tapering and discontinuation, and median SRoT duration was ~8 months until Month 12. Median platelet count increased within 1 month of treatment and remained elevated until Month 12. Quality of life improved within 3 months and was maintained. Headache (21%) was the most common adverse event. None of the 4 deaths reported were considered treatment-related. In summary, ~one-third of patients achieved SRoT until Month 12 following eltrombopag tapering and discontinuation. An ad-hoc early-use analysis, stratified by ITP duration at baseline, assessed initial hematologic responses and safety. Results suggest that eltrombopag has similar efficacy in newly diagnosed and later stages of ITP. In follow-up until Month 24, a median SRoT duration of ~22 months was observed (n = 20). The safety profile was comparable across analyses and ITP duration groups and aligned with its well-established safety profile.

Thrombopoietin-receptor agonists for adult patients with immune thrombocytopenia: a narrative review and an approach for managing patients fasting intermittently

Introduction

Thrombopoietin-receptor agonist (TPO-RAs) currently represent the state of art for treating immune thrombocytopenia. Their different molecular structures contribute to the difference in their pharmacodynamics and pharmacokinetics. This narrative review aims to provide an overview of the current TPO-RAs approved for primary immune thrombocytopenia (romiplostim, eltrombopag, avatrombopag) and the effect of intermittent fasting in adult patients receiving TPO-RAs.

Areas covered

Literature was searched with no limits on date or language, using various combinations of keywords. Data on the pharmacokinetics, pharmacodynamics, efficacy, and safety of TPO-RAs and the effect of intermittent fasting were summarized.

Expert opinion

Switching between TPO-RAs is a useful strategy to tackle some associated limitations. Romiplostim and avatrombopag have an advantage over eltrombopag as they do not require any dietary restrictions. In cases where romiplostim and avatrombopag are unavailable, patients should be educated on the appropriate administration, possible interactions, and dietary restrictions before initiating eltrombopag.

Efficacy and safety of QL0911 in adult patients with chronic primary immune thrombocytopenia: A multicenter, randomized, double-blind, placebo-controlled, phase III trial

Objective

QL0911, a recombinant human thrombopoietin mimetic peptide-Fc fusion protein, is a romiplostim (Nplate®) biosimilar used to treat primary immune thrombocytopenia (ITP). This phase III study aimed to assess the efficacy and safety of QL0911 in adult patients with chronic primary ITP over a 24-week treatment period.

Methods

We conducted a double-blind, placebo-controlled, phase III study in patients diagnosed with primary ITP for at least 12 months who had received at least one first-line ITP treatment with no response or recurrence after treatment, or who relapsed after splenectomy at 44 sites in China. Patients were randomly allocated (2:1 ratio) to QL0911 or placebo injection subcutaneously once weekly at an initial dose of 1 μg/kg for 24 weeks. The doses were adjusted to maintain the target platelet counts from 50 × 109/L to 200 × 109/L. Patients and investigators were blinded to the assignment. The primary endpoints were the proportion of patients who achieved a durable platelet response at week 24 (platelet count, ≥ 50 × 109/L during 6 of the last 8 weeks of treatment) and safety. The study was registered at ClinicalTrials.gov (NCT05621330).

Results

Between October 2019 and December 2021, 216 patients were randomly assigned (QL0911,144; placebo,72). A durable platelet response was achieved by significantly more patients in the QL0911 group (61.8%, 95% CI: 53.3-69.8; P < 0.0001) than in the placebo group (0%). The mean duration of platelet responses was 15.9 (SE: 0.43) weeks with QL0911, and 1.9 (SE:0.26) week with placebo. Consistent results were achieved in subgroup analyses categorized by baseline splenectomy status (yes/no), concomitant ITP treatment (yes/no), and baseline platelet count (≤ 10 × 109/L, > 10 × 109/L, ≤ 20 × 109/L, > 20 × 109/L, and < 30 × 109/L). The incidence of TEAEs was comparable between the QL0911 and the placebo groups (91.7% and 88.9%, respectively). The most common adverse events overall were ecchymosis (28.5% for QL0911 vs. 37.5% for placebo), upper respiratory tract infections respiratory tract infections (31.9% for QL0911 vs. 27.8% for placebo), and gingival bleeding (17.4% for QL0911 vs. 26.4% for placebo).

Conclusion

QL0911 was well-tolerated and increased and maintained platelet counts in adults with ITP. QL0911, a biosimilar to romiplostim (Nplate®), may be a novel treatment option for patients with ITP who have failed or relapsed from first-line treatment in China. Ongoing studies will provide further data on long-term efficacy and safety in such patient populations.

Recommendations for the Clinical Approach to Immune Thrombocytopenia: Spanish ITP Working Group (GEPTI)

Primary immune thrombocytopenia (ITP) is a complex autoimmune disease whose hallmark is a deregulation of cellular and humoral immunity leading to increased destruction and reduced production of platelets. The heterogeneity of presentation and clinical course hampers personalized approaches for diagnosis and management. In 2021, the Spanish ITP Group (GEPTI) of the Spanish Society of Hematology and Hemotherapy (SEHH) updated a consensus document that had been launched in 2011. The updated guidelines have been the reference for the diagnosis and management of primary ITP in Spain ever since. Nevertheless, the emergence of new tools and strategies makes it advisable to review them again. For this reason, we have updated the main recommendations appropriately. Our aim is to provide a practical tool to facilitate the integral management of all aspects of primary ITP management.

Immunomodulation with romiplostim as a second-line strategy in primary immune thrombocytopenia: The iROM study

Thrombopoietin receptor agonists (TPO-RAs) stimulate platelet production, which might restore immunological tolerance in primary immune thrombocytopenia (ITP). The iROM study investigated romiplostim's immunomodulatory effects. Thirteen patients (median age, 31 years) who previously received first-line treatment received romiplostim for 22 weeks, followed by monitoring until week 52. In addition to immunological data, secondary end-points included the sustained remission off-treatment (SROT) rate at 1 year, romiplostim dose, platelet count and bleedings. Scheduled discontinuation of romiplostim and SROT were achieved in six patients with newly diagnosed ITP, whereas the remaining seven patients relapsed. Romiplostim dose titration was lower and platelet count response was stronger in patients with SROT than in relapsed patients. In all patients, regulatory T lymphocyte (Treg) counts increased until study completion and the counts were higher in patients with SROT. Interleukin (IL)-4, IL-9 and IL-17F levels decreased significantly in all patients. FOXP3 (Treg), GATA3 (Th2) mRNA expression and transforming growth factor-β levels increased in patients with SROT. Treatment with romiplostim modulates the immune system and possibly influences ITP prognosis. A rapid increase in platelet counts is likely important for inducing immune tolerance. Better outcomes might be achieved at an early stage of autoimmunity, but clinical studies are needed for confirmation.

Early immunomodulation in immune thrombocytopenia-A report of the ICIS meeting in Lenzerheide, Switzerland 2022

The only way to prevent immune thrombocytopenia (ITP) from becoming refractory would be to restore tolerance to platelets at an early phase of the disease. Numerous immune alterations probably accumulate in chronic ITP; thus, the chances of cure decrease significantly with time. Currently, sustained remission off treatment (SROT) is a clinical definition describing patients who can discontinue their ITP treatment without risk and maintain a state of remission. Different treatment strategies are presently being evaluated with the goal of attaining SROT, mostly combining drugs targeting the innate and/or the adaptive immune system, the inflammation state, so as increasing the platelet load. In this sense, thrombopoietin receptor agonists (TPO-RAs) have shown promising results if used as upfront treatment. TPO-RAs seem to exhibit immunomodulation and immune tolerance properties, increasing not only the platelet antigen mass but also increasing the transforming growth factor-β concentration, and stimulating regulatory T and B lymphocytes. However, more immunological studies are needed to establish accurate molecular alterations in ITP that are potentially reversed with treatments.

Fostamatinib or Thrombopoietin for the Treatment of Chronic Immune Thrombocytopenia in Adult Patients: A Real-World Assessment of Safety, Effectiveness and Cost

INTRODUCTION

Chronic immune thrombocytopenia purpura (ITP) in adults is a serious autoimmune disease in which platelets are prematurely destroyed, leaving the patient vulnerable to bruising and bleeding. Initial treatment starts with corticosteroids. In patients who become resistant or intolerant to corticosteroids, the thrombopoietic agents (TPOs), consisting of romiplostim (ROM), eltrombopag (ELT), and avatrombopag (AVA), or the spleen tyrosine kinase inhibitor fostamatinib (FOS), are appropriate next lines of therapy. In this study, the comparative safety, effectiveness, and cost of care between fostamatinib and the TPOs were evaluated in a real-world setting.

METHODS

A retrospective analysis of 17 community hematology practices across the USA was conducted to identify adult ITP patients who received one of the four agents. Data collection consisted of patient demographics, disease characteristics, as well as number and type of prior treatments. From the first day until the end of treatment, data were also collected on platelet (PLT) counts, adverse events, the use of rescue IVIG, platelet transfusions, and corticosteroids. Multivariable logistic regression analysis was used to compare PLT-related endpoints between agents.

RESULTS

A sample of 179 ITP patients who had received at least one of the four agents was identified. This resulted in a final sample of 51, 87, 127, and 44 patients who received FOS, ELT, ROM, or AVA, respectively. At month six, there were no significant differences between FOS and the TPOs in terms of the proportion of patients with the PLT count being ≥30 × 103/μL, ≥50 × 103/μL as well as the proportion of patients whose PLT levels doubled relative to baseline. The frequency of thromboembolic events (TEs) was 3.9% in FOS patients compared to 9.2%, 4.7%, and 11.4% in the ELT, ROM, and AVA groups. The mean cost per patient with FOS was $99,209 (95% CI: $59,595-$115,074), compared to $92,426 (95% CI: $68,331-$115,519), $108,482 (95% CI: $84,782-$132,182), and $131,050 (95% CI: $83,327-$179,897) for ELT, ROM, or AVA, respectively.

CONCLUSIONS

In this real-world analysis, FOS was comparable to the TPOs in maintaining PLTs at clinically beneficial levels. Given these findings, the choice of therapy should be based on overall patient safety, preexisting risk factors for TEs, and cost effectiveness.

Risk of thrombotic events in immune thrombocytopenia patients treated with thrombopoietic agents: a systematic review and meta-analysis

BACKGROUND

Immune thrombocytopenia (ITP), which is a well-known hemorrhagic disorder characterized by low platelet counts, has been shown to be associated with the risk of thrombosis. Thrombopoietic agents (TAs) are extensively used as second-line treatments for ITP, effectively reducing the risk of hemorrhage. However, thrombosis, a potential adverse effect of TAs, raises clinical challenges.

METHODS

The MEDLINE(PubMed), Embase, and the Cochrane Library databases were systematically searched for relevant studies, including both single-arm trials and randomized controlled trials (RCTs), without language restrictions.

RESULTS

A total of 17 RCTs comprising 2,105 patients and 29 single-arm trials comprising 3,227 patients were included. In the single-arm meta-analysis, the pooled rate of overall thrombotic events in ITP patients receiving TAs was 2.2% (95% CI 1.0% - 3.7%). In RCTs, a higher incidence of thrombosis (33/1425 vs. 4/680) and higher risk ratios (RR) of overall, arterial, and venous thrombotic events (1.73, 95% CI [0.88, 3.39], P = 0.113; RR 1.98, 95% CI [0.80, 4.92], P = 0.141; RR 1.06, 95% CI [0.46, 2.41], P = 0.895, respectively) were observed in the TAs group than in the control group, although the differences were not significant. Subgroup analysis demonstrated that hetrombopag was the only TA with no increased thrombotic risk (rate 0.3% 95% CI [0.0 - 1.5%]; RR 0.76, 95% CI [0.03, 18.41], P = 0.864) compared to eltrombopag, avatrombopag, romiplostim, and rhTPO. Subgroup analyses also revealed that ITP patients with advanced age (3.7% vs. 1.3%, P = 0.132) or with a thrombotic history (3.0% vs. 1.4%, P = 0.257), and patients who received TAs therapy for a long duration (4.7% vs. 0.1%, P < 0.001) had an increased risk of thrombosis.

CONCLUSION

Our findings suggest ITP patients treated with TAs have a nonsignificantly higher risk of overall, arterial, and venous thrombotic events. Furthermore, hetrombopag is the recommended TA to avoid thrombophilia. Patients receiving long-term TAs, as well as elderly ITP patients or those with a history of thrombosis, face an increased thrombotic risk. In general, clinicians should consider potential thrombotic risks, address underlying risk factors, and ensure ongoing monitoring and follow-up when treating ITP patients with TAs.

In chronic lymphocytic leukemia, activation of the thrombopoietin receptor promotes T-cell inhibitory properties, contributing to immunosuppression

In chronic lymphocytic leukemia (CLL), the immune system is skewed towards a suppressive milieu. Levels of thrombopoietin (TPO), promoting cellular immune regulatory activity in immune thrombocytopenic purpura, were shown to be elevated in CLL patients. This study explored TPO as a potential immunomodulator, supporting CLL progression. We evaluated CLL cell-induced expression of TPO receptor (TPO-R) on T-cells and effects of its activation on T-cell responses. CLL cell involvement in TPO generation was also assessed. Baseline TPO-R expression on CD4 + T-cells was found to be higher in CLL patients than in healthy controls (HC). Exposure of HC-T-cells to B-cells, especially to CLL-B-cells stimulated with B-cell activating molecules, resulted in enhanced TPO-R expression on T-cells. CLL-T-cell stimulation with TPO reduced their proliferation and expanded the regulatory T-cell (Treg) population. At baseline, phosphorylation of STAT5, known to impact the Treg phenotype, was elevated in CLL-T-cells relative to those of HC. Exposure to TPO further enhanced STAT5 phosphorylation in CLL-T-cells, possibly driving the observed Treg expansion. The CLL immune milieu is involved in promotion of inhibitory features in T-cells through increased TPO-R levels and TPO-induced intracellular signaling. TPO and its signaling pathway could potentially support immunosuppression in CLL, and may emerge as novel therapeutic targets.

Use of thrombopoietin receptor agonists in adults with immune thrombocytopenia: a systematic review and Central European expert consensus

There are currently three thrombopoietin receptor agonists (TPO-RAs) approved in Europe for treating patients with immune thrombocytopenia (ITP): romiplostim (Nplate®), eltrombopag (Revolade®), and avatrombopag (Doptelet®). However, comparative clinical data between these TPO-RAs are limited. Therefore, the purpose of this study was to perform a literature review and seek expert opinion on the relevance and strength of the evidence concerning the use of TPO-RAs in adults with ITP. A systematic search was conducted in PubMed and Embase within the last 10 years and until June 20, 2022. A total of 478 unique articles were retrieved and reviewed for relevance. The expert consensus panel comprised ITP senior hematologists from eight countries across Central Europe. The modified Delphi method, consisting of two survey rounds, a teleconference and email correspondence, was used to reach consensus. Forty articles met the relevancy criteria and are included as supporting evidence, including five meta-analyses analyzing all three European-licensed TPO-RAs and comprising a total of 31 unique randomized controlled trials (RCTs). Consensus was reached on seven statements for the second-line use of TPO-RAs in the management of adult ITP patients. In addition, the expert panel discussed TPO-RA treatment in chronic ITP patients with mild/moderate COVID-19 and ITP patients in the first-line setting but failed to reach consensus. This work will facilitate informed decision-making for healthcare providers treating adult ITP patients with TPO-RAs. However, further studies are needed on the use of TPO-RAs in the first-line setting and specific patient populations.

Sustained Remission Off-Treatment (SROT) of TPO-RAs: The Burgos Ten-Step Eltrombopag Tapering Scheme

Background and Objectives: TPO-RAs (romiplostim/eltrombopag/avatrombopag) have broadly demonstrated high efficacy rates (59-88%), durable responses (up to three years) and a satisfactory safety profile in clinical trials. The effect of TPO-RAs is classically considered to be transient because platelet numbers usually dropped rapidly to baseline unless therapy was maintained. However, several groups have reported the possibility of successfully discontinuing TPO-RAs in some patients without further need for concomitant treatments. This concept is usually referred as sustained remission off-treatment (SROT). Materials and Methods: Unfortunately, we still lack predictors of the response to discontinuation even after the numerous biological, clinical and in vitro studies performed to study this phenomenon. The frequency of successful discontinuation is matter of controversy, although a percentage in the range of 25-40% may probably be considered a consensus. Here, we describe all major routine clinical practice studies and reviews that report the current position on this topic and compare them with our own results in Burgos. Results: We report our Burgos ten-step eltrombopag tapering scheme with which we have achieved an elevated percentage rate of success (70.3%) in discontinuing treatment. Conclusions: We hope this protocol may help successfully taper and discontinue TPO-RAs in daily clinical practice.

A bibliometric analysis of primary immune thrombocytopenia from 2011 to 2021

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia. This bibliometric analysis was applied to identify the characteristics of global scientific output, the hotspots, and frontiers of ITP over the past 10 years. We retrieved publications from 2011 to 2021 from the Web of Science Core Collection (WoSCC). Bibliometrix package, VOSviewer, and Citespace were used to analyse and visualize the trend, distribution, and hotspots of research on ITP. Altogether, there were 2084 papers, written by 9080 authors from 410 organizations in 70 countries/regions, published in 456 journals with 37 160 co-cited references. In the last decades, the most productive journal was British Journal of Haematology, China was the most productive country. and the most cited journal was Blood. Shandong University was the most productive institution in the field of ITP. NEUNERT C, 2011, BLOOD, CHENG G, 2011, LANCET, and PATEL VL, 2012, BLOOD were the top three most cited documents. "Thrombopoietin receptor agonist", "regulatory T cell" and "sialic acid" were three hotspots of the last decade. And "immature platelet fraction", "Th17", and "fostamatinib" would be research frontiers in the feature. The present study provided a novel insight for future research directions and scientific decision-making.

Intramuscular Anti-D treatment for immune thrombocytopenia: A single centre experience

Intravenous Anti-Rhesus-D immunoglobulin (Anti-D) is a first-line treatment option for immune thrombocytopenia in non-splenectomised and RhD-positive patients. In this report, we retrospectively review our experience with intramuscular (IM) Anti-D treatment in 74 adult patients between 1990 and 2018. We found that 73% of patients showed a response; almost all of them had complete responses (68.9%), and 26% achieved complete responses sustained at least 6 months after treatment discontinuation. [Correction added on 02 December 2022, after first online publication: In the preceding sentence, '(68.89%)' has been corrected to '(68.9%)' in this version.] No significant side effects were observed with no cases of acute haemolysis or anaemia reported. We conclude from this study that IM Anti-D is an effective and safe treatment for immune thrombocytopenia.

Current approaches for the diagnosis and management of immune thrombocytopenia

Immune thrombocytopenia (ITP), is an acquired autoimmune disorder characterized by the destruction of platelets and megakaryocytes, resulting in thrombocytopenia (platelet count <100 × 10⁹/L). This review focuses on the diagnosis and current management of ITP. The diagnosis of ITP is based principally on the exclusion of other causes of isolated thrombocytopenia using patient history, physical examination, blood count, and evaluation of the peripheral blood film. The clinical treatment goals should be to resolve bleeding events and to prevent severe bleeding episodes. The platelet count should be improved to attain a minimum of > 20-30 × 10⁹/L. Therapy should be given as an inpatient in newly diagnosed ITP with a platelet count of > 20 × 10⁹/L or if there is active bleeding. Corticosteroids are considered the standard initial treatment for newly diagnosed patients. Subsequent medical therapies with robust evidence include thrombopoietin receptor agonists (TPO-RAs), rituximab and fostamatinib. Surgical therapy with splenectomy may be considered for patients failing medical therapy. The choice between therapy options is highly dependent upon patient values and preferences.

Nationwide Survey on the Use of Thrombopoietin Receptor Agonists (TPO-RA) for the Management of Immune Thrombocytopenia in Current Clinical Practice in Italy

Background

Two thrombopoietin receptor agonists (TPO-RA), romiplostim and eltrombopag, are currently widely adopted as second-line ITP therapy even in the absence of robust evidence on their comparative advantages over rituximab or splenectomy or their preferential use in some specific clinical contexts.

Methods

An online survey was distributed between May 2021 and June 2021 to collect standardized information on TPO-RA use in Italy.

Results

Eighty-eight hematologists from 79 centers completed the survey. Eighty-four percent would use TPO-RA earlier than formally indicated, without a preference for young or elderly in 82% of respondents. No clear preference for either romiplostim or eltrombopag was indicated. Seventy-two percent would use TPO-RA in young patients aiming at a complete response followed by tapering, a strategy considered by only 16% in the elderly. Switching between the two agents was considered appropriate in case of insufficient response or intolerance. Tapering schedule by reducing the dosage and prolonging the intervals between administrations was preferred by 73% of respondents. TPO-RA was considered a risk factor for thrombosis by only 35%, and 94% would administer TPO-RA in elderly patients also in the presence of other thrombotic risk factors. Thirty-three percent of respondents would withdraw TPO-RA in case of thrombosis. The TPORA administration has been reported to be preferred over anti-CD20 or splenectomy by about half of the participants due to the ongoing COVID-19 pandemic.

Conclusions

Significant discrepancies in TPO-RA use emerged from the survey, and participants would appreciate consensus-based specific guidance on the practical use of TPO-RA.

Efficacy and quality of life of Romiplostim in adults and children with immune thrombocytopenia: A review

BACKGROUND

To systematically evaluate the clinical efficacy, drug safety and health-related quality of life (HRQoL) of Romiplostim in adult and child immune thrombocytopenia (ITP) patients.

METHODS

PubMed, EMBASE and Cohrane library databases were searched for all randomized controlled trials published until 2022, and the Review Manager 5.3 was used for meta-analysis.

RESULTS

A total of 9 randomized controlled trials were included in this study. The results of meta-analysis showed that the total platelet response rate and long-term platelet response rate in treatment group were significantly higher than those in control group (P<0.05). There was no statistical significance in the side effects, serious side effects, bleeding events and serious bleeding events between 2 groups (P>0.05). Compared with control group, the HRQoL in ITP adults and children, and parents of ITP children had no statistical significance (P>0.05).

CONCLUSION

Romiplostim has a certain clinical efficacy in ITP adults and children, and relatively small adverse drug reactions. The improvement of Romiplostim on HRQoL in ITP adults and children is not clear.

SAFETY STUDY OF ROMIPLOSTIM BIOSIMILAR

Idiopathic thrombocytopenic purpura is a chronic autoimmune hematological disease caused by an increased destruction of platelets and associated thrombocytopenia, for the treatment of which the imported drug romiplostim is used. Сreation of the drug biosimilar provides a reduction in the cost of therapy and an access for the treatment to more patients.

The aim of the study was to compare the safety indicators of the reference drug and its biosimilar in vivo and in vitro.

Materials and methods. In the in vitro study, a model of “complement-dependent cytotoxicity” induced by the complement was formed on the 32D hTPOR clone 63-cell line, followed by a cell viability measurement with the CellTitter Glo® kit. An in vivo part of the study was carried out on Javanese macaque monkeys (Macaca fascicularis). During the experiment, the clinical condition, mortality, appetite of the animals, their body weight, body temperature, respiratory rate were assessed, the clinical parameters of blood and urine of the animals were also monitored, and the hemostasis indicators were additionally measured.

Results. In the in vitro experiment, the original drug romiplostim and its biosimilar GP40141 were compared in terms of EC50 values. The indicatirs did not show complement-dependent cytotoxicity. According to the in vivo results, no deviations were recorded in the clinical status of the animals and their feed intake, and no lethality was fixed out in the groups either. For all the parameters studied (body weight and temperature, respiratory rate, clinical urinalysis, clinical and biochemical blood tests, coagulation hemostasis), GP40141 and romiplostim, when administered at the doses equivalent to 10 toxic doses (TDs), had comparable effects.

Conclusion. In the comparison of safety performance both in vitro and in vivo, the original drug romiplostim and its biosimilar GP40141 showed similar results.

Efficacy and steroid-sparing effect of tacrolimus in patients with autoimmune cytopenia

The aim of this study was to evaluate the efficacy, safety, and steroid-sparing effect of tacrolimus in patients with autoimmune cytopenia, including immune thrombocytopenia (ITP), autoimmune hemolytic anemia (AIHA), and Evans syndrome (ES). Patients in the tacrolimus group were treated with tacrolimus in combination with steroids, and the control group received only steroids. Of the 318 patients finally enrolled, 87 (27.4%) were males, with a median age of 45 (14-90) years. The tacrolimus group comprised 144 patients, including 120 ITP, 19 AIHA, and 5 ES patients, and the control group comprised 174 patients, including 141 ITP, 25 AIHA, and 8 ES patients. The optimal ORR of the tacrolimus group was comparable to that of the control group, and the optimal CRR was higher (p < 0.05). Patients receiving tacrolimus had a decreased relapse rate and prolonged relapse-free survival (p < 0.05) compared with the controls for both the whole cohort and the ITP and AIHA subgroups. Compared with the control group, the tacrolimus group had a lower cumulative steroid dosage and earlier discontinuation of steroids (p < 0.05), which resulted in a decreased incidence of steroid-related adverse events (p < 0.05) although the total side effects were similar between the two groups. Similar drug expenses were observed between the tacrolimus and control groups at the 18-month follow-up. In conclusion, the early addition of tacrolimus had a similar ORR, better CRR, lower relapse rate, and prolonged relapse-free survival compared to steroids alone, with reduced steroid-related adverse events.

Thrombopoietin receptor agonist discontinuation rates and reasons among patients with immune thrombocytopenia: a study of administrative claims linked with medical chart review

Administrative claims provide a rich data source for retrospective studies of real-world clinical practice, yet some important data may be inconsistent or unavailable. This study explored factors influencing discontinuation of thrombopoietin receptor agonists (TPO-RAs) among patients with immune thrombocytopenia (ITP), by adding medical chart abstraction for additional details. Adult (≥ 18 years) patients with continuous commercial or Medicare Advantage with Part D health insurance coverage were included. Inclusion criteria were ≥ 1 claim for eltrombopag or romiplostim and ≥ 2 diagnoses of ITP between December 31, 2017, and January 1, 2020. Providers were asked to provide access to medical charts for abstraction. The analyses included only patients who discontinued TPO-RA and described patient characteristics, treatment patterns, platelet values, and reasons for discontinuation. Among 207 ITP patients treated with a TPO-RA, 137 (66%) discontinued treatment during the observation period. The mean TPO-RA treatment duration was 185 days. Mean platelet count at the time of discontinuation was 197 × 10⁹/L. The most common reason for discontinuation was improvement of the patient's condition (42%). Other reasons included worsening of ITP/lack of response (12%), adverse events (12%), and cost-related or social reasons (23%). No reason was reported for 10%. Notably 26% of patients who discontinued remained off all ITP therapy for the remainder of the study, with a mean treatment-free period of 262 days. These results emphasize that some patients with ITP are able to discontinue TPO-RA therapy and achieve durable treatment-free periods.

Novel Therapies to Address Unmet Needs in ITP

Primary immune thrombocytopenia (ITP) is an autoimmune disorder that causes low platelet counts and subsequent bleeding risk. Although current corticosteroid-based ITP therapies are able to improve platelet counts, up to 70% of subjects with an ITP diagnosis do not achieve a sustained clinical response in the absence of treatment, thus requiring a second-line therapy option as well as additional care to prevent bleeding. Less than 40% of patients treated with thrombopoietin analogs, 60% of those treated with splenectomy, and 20% or fewer of those treated with rituximab or fostamatinib reach sustained remission in the absence of treatment. Therefore, optimizing therapeutic options for ITP management is mandatory. The pathophysiology of ITP is complex and involves several mechanisms that are apparently unrelated. These include the clearance of autoantibody-coated platelets by splenic macrophages or by the complement system, hepatic desialylated platelet destruction, and the inhibition of platelet production from megakaryocytes. The number of pathways involved may challenge treatment, but, at the same time, offer the possibility of unveiling a variety of new targets as the knowledge of the involved mechanisms progresses. The aim of this work, after revising the limitations of the current treatments, is to perform a thorough review of the mechanisms of action, pharmacokinetics/pharmacodynamics, efficacy, safety, and development stage of the novel ITP therapies under investigation. Hopefully, several of the options included herein may allow us to personalize ITP management according to the needs of each patient in the near future.

Generic romiplostim for children with persistent or chronic immune thrombocytopenia: Experience from a tertiary care centre in North India

Thrombopoietin receptor agonists are important therapeutic option in children with immune thrombocytopenia (ITP). We evaluated the response, efficacy, safety of a generic form of romiplostim manufactured in India for treating children with persistent/chronic ITP at our centre. Study of 45 children with persistent/chronic ITP was conducted of which 5 discontinued and 40 were included between 2019-2020. Patients received romiplostim for 20 weeks, at a dose of 5 mcg/kg/week. Platelet count at week 1, 3, 20 and 26 was assessed. Predesigned algorithm was used for dose adjustment. After 20 weeks, patients who had platelet count of 50 × 109/L or above were tapered off medication and monitored till 26 weeks. Median platelet count at enrolment was 11 x 109/L (IQR 23 X 109/L). 13/40 children had received >/= three lines of prior ITP therapy. Platelet response (platelet count rise to more than 50×109/L without rescue medications) observed in 26 (65%) patients at week 20. Rescue medication was used in 12/40 children. Sustained platelet response after tapering and stopping romiplostim observed in 22/40 children. No adverse events were considered serious or led to discontinuation of treatment. Our data demonstrated generic romiplostim is well tolerated and efficacious in children with persistent/chronic ITP.

Primary immune thrombocytopenia in adults: Belgian recommendations for diagnosis and treatment anno 2021 made by the Belgian Hematology Society

The Belgian Hematology Society (BHS) updated the 2013 guidelines for diagnosis and treatment of primary immune thrombocytopenia (ITP) [1]. As knowledge about ITP pathophysiology is increasing, the mode of action of old therapies is better understood and novel drugs are introduced to target more specific pathways.Corticosteroids with or without intravenous immunoglobulins (IgIV) remain the first-line treatment. According to the updated international guidelines a short course of corticosteroids rather than a prolonged treatment has to be recommended. The same guidelines stress that consequent therapies as thrombopoietic agents (TPO-RAs) and rituximab should be available independent of duration of ITP.Although the majority of recommendations is based on very low-quality evidence, it is strongly advised to individualize the ITP management taking patient values. and preferences in account. The main treatment goal in all ITP patients must be to maintain a safe platelet count to prevent or stop bleeding with a minimum of toxicity and not to normalize the platelet count.

Management of immune thrombocytopenia: 2022 update of Korean experts recommendations

Despite the availability of therapies to treat patients with immune thrombocytopenia (ITP), there is currently little data from randomized trials to assist clinicians in managing patients. The evidence-based guidelines of the Korean Society of Hematology Aplastic Anemia Working Party (KSHAAWP) are intended to support patients and physicians in the management of ITP. Experts from the KSHAAWP discussed and described this guideline according to the current treatment situation for ITP in Korea and finalized the guidelines. The expert panel recommended the management of ITP in adult and pediatric patients with newly diagnosed, persistent, and chronic disease refractory to first-line therapy with minor bleeding. Management approaches include observation and administration of corticosteroids, intravenous immunoglobulin, anti-D immunoglobulin, and thrombopoietin receptor agonists. Currently, evidence supporting strong recommendations for various management approaches is lacking. Therefore, a large focus was placed on shared decision-making, especially regarding second-line treatment.

Dose tapering to withdrawal stage and long-term efficacy and safety of hetrombopag for the treatment of immune thrombocytopenia: Results from an open-label extension study

BACKGROUND

The efficacy of hetrombopag in Chinese patients with immune thrombocytopenia (ITP) has been demonstrated in a randomized, double-blind, placebo-controlled, multicenter, phase III trial (NCT03222843).

OBJECTIVE

This study aimed to report comprehensive data on a ≤6-week dose tapering to withdrawal (Stage 3) and an additional 24-week long-term extension period (Stage 4) in this phase III trial.

PATIENTS/METHODS

Patients who fulfilled the screening criteria were eligible to enter Stage 3 or 4. During Stage 3, hetrombopag was gradually tapered to withdrawal. During Stage 4, hetrombopag treatment was initiated at 2.5, 3.75, 5, or 7.5 mg once daily. The efficacy endpoints during Stage 3 or 4 and the safety profile during the entire treatment period were reported.

RESULTS

Among 194 patients who entered Stage 3, 171 (88.1%) relapsed. The median time to the first relapse since the start of Stage 3 was 15.0 days (95% CI, 14.0-16.0). In Stage 4, 144 (42.5%) patients responded at ≥75% of their assessments and 254 (74.9%) patients achieved platelet count ≥30 × 109 /L at least once, which was at least twice their baseline platelet count in the hetrombopag group (n = 339). The most common adverse events were upper respiratory tract infection (53.1%), thrombocytopenia (27.1%), and urinary tract infection (21.2%) in the hetrombopag group.

CONCLUSION

The majority of patients who experienced dose tapering to withdrawal experienced a relapse. Long-term treatment with hetrombopag was effective in increasing and maintaining platelet count within the desired range in Chinese adults with ITP. Hetrombopag was well tolerated.

Refractory primary immune thrombocytopenia (ITP): current clinical challenges and therapeutic perspectives

Chronic primary immune thrombocytopenia (ITP) can today benefit from multiple therapeutic approaches with proven clinical efficacy, including rituximab, thrombopoietin receptor agonists (TPO-RA), and splenectomy. However, some ITP patients are unresponsive to multiple lines of therapy with prolonged and severe thrombocytopenia. The diagnosis of refractory ITP is mainly performed by exclusion of other disorders and is based on the clinician's expertise. However, it significantly increases the risk of drug-related toxicity and of bleedings, including life-threatening events. The management of refractory ITP remains a major clinical challenge. Here, we provide an overview of the currently available treatment options, and we discuss the emerging rationale of new therapeutic approaches and their strategic combination. Particularly, combination strategies may target multiple pathogenetic mechanisms and trigger additive or synergistic effects. A series of best practices arising both from published studies and from real-life clinical experience is also included, aiming to optimize the management of refractory ITP.

Immune thrombocytopenia

INTRODUCTION

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by a low platelet count (<100 × 10⁹/L) with an increased risk of bleeding. Recent (2019) guidelines from the International Consensus Report (ICR) expert panel and the American Society of Hematology (ASH) provide updated recommendations for the diagnosis and management of ITP.

AREAS COVERED

The 2019 ICR and ASH guidelines are reviewed, and differences and similarities highlighted. Clinical approaches to the treatment of ITP are discussed, including the role of fostamatinib which is an approved treatment option in adult patients who are refractory to other treatments.

EXPERT OPINION

The 2019 ICR and ASH guidelines reflect recent changes in the management of ITP. Current treatment approaches for ITP are more rational and evidence-based than in the past. Patients should be treated based on their needs rather than on disease stage, and patient-specific outcomes, (e.g. quality of life) should be considered. Whilst corticosteroids are the mainstay of initial ITP treatment their use should be limited. For subsequent treatment, the use of thrombopoietin receptor agonist (TPO-RA) agents, fostamatinib and rituximab in adults is supported by robust evidence. Rituximab and recently approved fostamatinib offer viable alternatives to splenectomy.

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.

Novel therapies for immune thrombocytopenia

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

Experts' review: the emerging roles of romiplostim in immune thrombocytopenia (ITP)

INTRODUCTION

The management of ITP has in recent years been transformed from reliance on immunosuppressants and splenectomy to targeted therapy with thrombopoietin receptor agonists (TPO-RA) that directly stimulate platelet production in the bone marrow. This has reduced the long-term infective complications and toxicities associated with the use of potent immunosuppressants and splenectomy. The welltolerated romiplostim, itself a novel drug construct called peptibody, has established itself, alongside other TPO-RA as the preferred 2nd line therapy in major international guidelines on treatment of ITP.

AREAS COVERED

This review summarizes the data from early licensing trials of romiplostim and discusses the real-world experience to date, the unexpected emerging data on treatment-free long-term remission achieved using TPO-RA, and the case for its early introduction in the therapeutic pathway. The emerging risk of thrombosis is also discussed.

EXPERT OPINION

The use of romiplostim and other TPO-RA will be increasingly brought forward in the management pathway of ITP with the prospect of modifying the long-term outcome of the disease by increasing sustained treatment-free remission. With the prospect of several new targeted therapies been introduced into clinical practice, TPO-RA will likely be a key component of future combination therapies for difficult cases.

Effectiveness and safety of romiplostim among patients with newly diagnosed, persistent and chronic ITP in routine clinical practice in central and Eastern Europe: an analysis of the PLATON study

OBJECTIVES

The objective of this analysis was to assess the effectiveness and safety of romiplostim in the real-world by duration of primary immune thrombocytopenia (ITP): <3 ('newly diagnosed'), 3-12 ('persistent'), and >12 ('chronic') months.

METHODS

This was a post-hoc analysis of the PLATON single-arm, observational cohort study of adults from five Central and Eastern European countries receiving ≥1 romiplostim dose as second-line therapy, or where surgery was contraindicated. Durable (≥75% of measurements with ≥50 × 10⁹ platelets/L during weeks 14-24) and overall platelet response (≥30 or ≥50 × 10⁹ platelets/L at least once), rescue therapy, bleeding, discontinuation of other ITP medications, and adverse drug reactions (ADRs) were assessed.

RESULTS

Of 100 participants, 22.0% had newly diagnosed, 17.0% had persistent, and 61.0% had chronic ITP. Prior splenectomy was most frequently reported in chronic ITP (32.8%), prior bleeding was predominant in newly diagnosed patients (68.2%). Durable platelet response was achieved in 50.0% (95% confidence interval [CI]: 28.2-71.8%) of newly diagnosed, 35.3% (95% CI: 14.2-61.7%) of persistent, and 31.1% (95% CI: 19.9-44.3%) of chronic ITP patients. Overall platelet response was achieved in >80% across all strata. Safety was comparable across groups, with a low incidence of thrombotic ADRs and no bone marrow ADRs.

DISCUSSION

In this real-world study, platelet response to romiplostim was consistent across all strata of ITP duration. ADRs were infrequent and similar across ITP settings.

CONCLUSION

These findings support the utilization of romiplostim in patients with newly diagnosed and persistent ITP in accordance with recent guidelines and the recent romiplostim label extension.

A Review of Romiplostim Mechanism of Action and Clinical Applicability

Thrombocytopenia results from a variety of conditions, including radiation, chemotherapy, autoimmune disease, bone marrow disorders, pathologic conditions associated with surgical procedures, hematopoietic stem cell transplant (HSCT), and hematologic disorders associated with severe aplastic anemia. Immune thrombocytopenia (ITP) is caused by immune reactions that accelerate destruction and reduce production of platelets. Thrombopoietin (TPO) is a critical component of platelet production pathways, and TPO receptor agonists (TPO-RAs) are important for the management of ITP by increasing platelet production and reducing the need for other treatments. Romiplostim is a TPO-RA approved for use in patients with ITP in the United States, European Union, Australia, and several countries in Africa and Asia, as well as for use in patients with refractory aplastic anemia in Japan and Korea. Romiplostim binds to and activates the TPO receptor on megakaryocyte precursors, thus promoting cell proliferation and viability, resulting in increased platelet production. Through this mechanism, romiplostim reduces the need for other treatments and decreases bleeding events in patients with thrombocytopenia. In addition to its efficacy in ITP, studies have shown that romiplostim is effective in improving platelet counts in various settings, thereby highlighting the versatility of romiplostim. The efficacy of romiplostim in such disorders is currently under investigation. Here, we review the structure, mechanism, pharmacokinetics, and pharmacodynamics of romiplostim. We also summarize the clinical evidence supporting its use in ITP and other disorders that involve thrombocytopenia, including chemotherapy-induced thrombocytopenia, aplastic anemia, acute radiation syndrome, perisurgical thrombocytopenia, post-HSCT thrombocytopenia, and liver disease.

How I treat primary ITP in adult patients who are unresponsive to or dependent on corticosteroid treatment

Approximately 80% of adult patients with immune thrombocytopenia (ITP) have treatment failure with corticosteroids or become dependent on them and require second-line therapy. Several new and effective therapies have been introduced during the past decade and our understanding of disease burden and its effect on quality of life has expanded. It is now recommended that splenectomy, the standard second-line therapy for decades, be delayed for at least 12 to 24 months, allowing for more patients to achieve remission on medical therapies before considering surgery. It is highly recommended that medical therapies be used that have abundant clinical trial evidence, such as the thrombopoietin receptor agonists (TPO-RAs) rituximab and fostamatinib. Unfortunately, there are no reliable biomarkers that help in treatment selection. These therapeutic medical options have variable efficacy, safety profiles, mechanisms of action, and modes of administration. This enables and mandates an individualized approach to treatment, where patient involvement, preferences and values have become central to the process of choosing the appropriate therapy. Both TPO-RAs and fostamatinib are maintenance therapies, whereas rituximab is given for a limited number of doses. Although the response is usually maintained while receiving a TPO-RA or fostamatinib therapy, half of rituximab responders will no longer respond 1 to 2 years after administration and require retreatment or other therapy.

Real-world use of thrombopoietin receptor agonists in elderly patients with primary immune thrombocytopenia

The efficacy and safety of thrombopoietin-receptor agonists (TRAs) in elderly patients with primary immune thrombocytopenia (ITP) is uncertain. In 384 ITP patients treated with TRAs when aged ≥60 years, we investigated TRAs response and switch, thrombotic/hemorrhagic risk, and sustained responses off-treatment (SROT). After 3 months, 82.5% and 74.3% of eltrombopag and romiplostim-treated patients achieved a response, respectively (p=0.09); 66.7% maintained the response (median follow-up: 2.7 years). Eighty-five (22.2%) patients switched to the alternative TRA; while no cross-toxicity was observed, 83.3% of resistant patients had a response after the switch. During TRA, 34 major thromboses (3 fatal) and 14 major hemorrhages (none fatal) occurred in 18 and 10 patients, respectively, and were associated with thrombosis history (SHR: 2.04, p=0.05) and platelet count <20x109/L at TRA start (SHR: 1.69, p=0.04), respectively. A recurrent event occurred in 15.6% of patients surviving thrombosis, in all cases but one during persisting TRA treatment (incidence rate: 7.7 per 100 patient-years). All recurrences occurred in the absence of adequate antithrombotic secondary prophylaxis. Sixty-two (16.5%) responding patients discontinued TRA; 53 (13.8%) patients maintained SROT, which was associated with TRA discontinuation in complete response (p<0.001). Very old age (≥75, 41.1%) was associated with more frequent TRAs start in persistent/acute phase but not with response or thrombotic/hemorrhagic risk. TRAs are effective in elderly ITP patients, with no fatal haemorrhages and with SROT in a significant portion of patients; in patients with thrombosis history caution is warranted and a careful risk/benefit balance should be carried out.

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.

Platelet desialylation and TFH cells-the novel pathway of immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by immune-mediated destruction of one's own platelets. The progression of thrombocytopenia involves an imbalance of platelet production and clearance. B cells can induce autoantibodies, and T cells contribute to the pathological progression as well. Some patients with ITP have a poor response to common first-line therapies. Recent studies have shown that a novel Fc-independent platelet clearance pathway is associated with poor prognosis in these patients. By this pathway, desialylated platelets can be cleared by Ashwell-Morell receptor (AMR) on hepatocytes. Research has demonstrated that patients with refractory ITP usually have a high level of desialylation, indicating the important role of sialylation on platelet membrane glycoprotein (GP) in patients with primary immune thrombocytopenia, and neuraminidase 1(NEU1) translocation might be involved in this process. Patients with ITP who are positive for anti-GPIbα antibodies have a poor prognosis, which indicates that anti-GPIbα antibodies are associated with this Fc-independent platelet clearance pathway. Experiments have proven that these antibodies could lead to the desialylation of GPs on platelets. The T follicular helper (TFH) cell level is related to the expression of the anti-GPIbα antibody, which indicates its role in the progression of desialylation. This review will discuss platelet clearance and production, especially the role of the anti-GPIbα antibody and desialylation in the pathophysiology of ITP and therapy for this disease.

Immune thrombocytopenia: A review of upfront treatment strategies

Immune thrombocytopenia (ITP), resulting from antibody-mediated platelet destruction combined with impaired platelet production, is a rare cause of thrombocytopenia in both children and adults. The decision to treat newly diagnosed patients is based on several factors, including the desire to increase platelet count to prevent bleeding, induce remission, and improve health-related quality of life (HRQoL). At present, standard first-line therapy is corticosteroids. While this treatment does increase the platelet count in many patients, a high percentage still relapse after discontinuation of therapy. For this reason, alteration or intensification of first-line therapy that results in superior long-term remission rates is desirable. The objective of this review is to outline different upfront strategies for newly diagnosed patients with ITP in an effort to potentially enhance remission rates and prevent relapse, taking into account an assessment of the risks and benefits of each approach. We primarily focus on adults with ITP, highlighting pediatric data and practice when applicable.

Clinical overview and practical considerations for optimizing romiplostim therapy in patients with immune thrombocytopenia

The fundamental treatment goal for patients with immune thrombocytopenia (ITP) is reduced or ameliorated bleeding. Although various treatment options exist for the management of ITP, recent advances have led to the approval of three thrombopoietin receptor agonists (TPO-RAs; romiplostim, eltrombopag, and avatrombopag) in the United States and European Union. Current treatment guidelines for ITP indicate that medical therapy is preferred over surgical therapy and support the use of TPO-RAs as early as 3 months after disease onset. More recent data are available on the use of romiplostim in patients who have had ITP for <1 year, and romiplostim is now indicated for the treatment of adults who have not responded adequately to initial treatment, as well as children aged ≥1 year who have had ITP for ≥6 months. Here we review the role of romiplostim in the management of ITP, with a focus on efficacy and safety data, emerging data on early use (beginning within 3 months of disease onset) and treatment-free remission, and practical considerations for optimal management of ITP.

Eltrombopag second-line therapy in adult patients with primary immune thrombocytopenia in an attempt to achieve sustained remission off-treatment: results of a phase II, multicentre, prospective study

Up to 30% immune thrombocytopenia (ITP) patients achieve a sustained remission off-treatment (SROT) after discontinuation of thrombopoietin receptor agonists (TPO-RAs). Factors predictive of response are lacking. Patients aged ≥18 years with newly diagnosed or persistent ITP were treated with eltrombopag for 24 weeks. Primary end-point was SROT: the proportion of responders that were able to taper and discontinue eltrombopag maintaining the response during a period of observation (PO) of six months. Secondary end-points included the association between some immunological parameters (TPO serum levels, cytokines and lymphocyte subsets) and response. Fifty-one patients were evaluable. Primary end-point was achieved in 13/51 (25%) treated patients and 13/34 (38%) patients who started the tapering. Baseline TPO levels were not associated with response at week 24 nor with SROT. Higher baseline levels of IL-10, IL-4, TNF-α and osteopontin were negative factors predictive of response (P = 0·001, 0·008, 0·02 and 0·03 respectively). This study confirms that SROT is feasible for a proportion of ITP patients treated with eltrombopag. Some biological parameters were predictive of response.

A Case of Epistaxis as the First Sign of Acute Idiopathic Thrombocytopenic Purpura

Idiopathic thrombocytopenic purpura (ITP) is an acquired thrombocytopenia caused by the action of autoantibodies against platelet antigens. It is traditionally defined by a platelet count of less than 10 × 10⁴/μL. Most patients with ITP are asymptomatic; however, symptoms have been confirmed in some cases. Conversely, it is very rare to find epistaxis as the first sign of ITP. We report the case of an 84-year-old man who came to the ear, nose, and throat department with severe and repeated epistaxis. We decided to keep him hospitalized as it was very difficult to stop the nasal bleeding. A full blood count showed a platelet level of only 1000/μL. Hematologic results confirmed the diagnosis of ITP. The patient underwent treatment with intravenous gamma-globulin, platelet transfusions, and romiplostim with a favorable response.

Immune thrombocytopenia (ITP) World Impact Survey (iWISh): Patient and physician perceptions of diagnosis, signs and symptoms, and treatment

Immune thrombocytopenia (ITP) is now well-known to reduce patients' health-related quality of life. However, data describing which signs and symptoms patients and physicians perceive as having the greatest impact are limited, as is understanding the full effects of ITP treatments. I-WISh (ITP World Impact Survey) was an exploratory, cross-sectional survey designed to establish the multifaceted impact of ITP, and its treatments, on patients' lives. It focused on perceptions of 1507 patients and 472 physicians from 13 countries regarding diagnostic pathway, frequency and severity of signs and symptoms, and treatment use. Twenty-two percent of patients experienced delayed diagnosis (caused by several factors), 73% of whom felt anxious as a result. Patients rated fatigue among the most frequent, severe symptom associated with ITP at diagnosis (58% most frequent; 73% most severe), although physicians assigned it lower priority (30%). Fatigue was one of the few symptoms persisting at survey completion (50% and 65%, respectively) and was the top symptom patients wanted resolved (46%). Participating physicians were experienced at treating ITP, thereby recognizing the need to limit corticosteroid use to newly-diagnosed or first-relapse patients and espoused increased use of thrombopoietin receptor agonists and anti-CD20 after relapse in patients with persistent/chronic disease. Patient and physicians were largely aligned on diagnosis, symptoms, and treatment use. I-WISh demonstrated that patients and physicians largely align on overall ITP symptom burden, with certain differences, for example, fatigue. Understanding the emotional and clinical toll of ITP on the patient will facilitate shared decision-management, setting and establishment of treatment goals and disease stage-appropriate treatment selection.

Tapering thrombopoietin receptor agonists in primary immune thrombocytopenia: Expert consensus based on the RAND/UCLA modified Delphi panel method

BACKGROUND

Thrombopoietin receptor agonists (TPO-RAs) are used to treat primary immune thrombocytopenia (ITP). Some patients have discontinued treatment while maintaining a hemostatic platelet count.

OBJECTIVES

To develop expert consensus on when it is appropriate to consider tapering TPO-RAs in ITP, how to taper patients off therapy, how to monitor patients after discontinuation, and how to restart therapy.

METHODS

We used a RAND/UCLA modified Delphi panel method. Ratings were completed independently by each expert before and after a meeting. Second-round ratings were used to develop the panel's guidance. The panel was double-blinded: The sponsor and nonchair experts did not know each other's identities.

RESULTS

Guidance on when it is appropriate to taper TPO-RAs in children and adults was developed based on patient platelet count, history of bleeding, intensification of treatment, trauma risk, and use of anticoagulants/platelet inhibitors. For example, it is appropriate to taper TPO-RAs in patients who have normal/above-normal platelet counts, have no history of major bleeding, and have not required an intensification of treatment in the past 6 months; it is inappropriate to taper TPO-RAs in patients with low platelet counts. Duration of ITP, months on TPO-RA, or timing of platelet response to TPO-RA did not have an impact on the panel's guidance on appropriateness to taper. Guidance on how to taper patients off therapy, how to monitor patients after discontinuation, and how to restart therapy is also provided.

CONCLUSION

This guidance could support clinical decision making and the development of clinical trials that prospectively test the safety of tapering TPO-RAs.