Novel therapies for immune thrombocytopenia

Efficacy and safety analysis of China's first 10% IVIg (RonsenGlob) therapy in treating adult ITP

A prospective, single-arm, open-label Phase III clinical trial was conducted across multiple centers in China from April 27, 2020, to June 15, 2021, to assess the efficacy and safety of 10% intravenous immunoglobulin (IVIg) in treating adult immune thrombocytopenic purpura (ITP). Within 7 days of treatment initiation, the 10% IVIg group exhibited an overall response rate of 87.0%, with 32 patients (46.4%) achieving complete response and 28 patients (40.6%) demonstrating partial response, comparable to the 5% IVIg group. Notably, the median time to achieve a platelet count (PLT) of 50 × 109/L was significantly shorter for the 10% IVIg group at 2 days (IQR: 2-3) versus 3 days (IQR: 3-5) for the 5% IVIg group. Additionally, the 10% IVIg group reached a PLT of 100 × 109/L in 3 days (IQR: 3-4), compared to 5 days (IQR: 4-6) for the 5% IVIg group. Post-treatment bleeding scores significantly decreased, and no significant adverse reactions were reported. This inaugural study highlights the efficacy and safety of 10% IVIg in the urgent management of adult ITP, positioning it as a rapid therapeutic option.

Efficacy and Safety Results With Rilzabrutinib, an Oral Bruton Tyrosine Kinase Inhibitor, in Patients With Immune Thrombocytopenia: Phase 2 Part B Study

Current treatments for persistent or chronic immune thrombocytopenia (ITP) are limited by inadequate response, toxicity, and impaired quality of life. The Bruton tyrosine kinase inhibitor rilzabrutinib was evaluated to further characterize safety and durability of platelet response. LUNA2 Part B is a multicenter, phase 1/2 study in adults with ITP (≥ 3 months duration, platelet count < 30 × 109/L) who failed ≥ 1 ITP therapy (NCT03395210, EudraCT 2017-004012-19). Oral rilzabrutinib 400 mg bid was given over 24 weeks, with optional long-term extension (LTE). Primary endpoints were safety and platelet counts ≥ 50 × 109/L on ≥ 8 of the last 12 weeks of main treatment without rescue medication. From 22 March2018 to 31 January2023, 26 patients were enrolled. Patients had baseline median platelet count 13 × 109/L, ITP duration 10.3 years, and six prior ITP therapies (46% splenectomized). Nine (35%) patients achieved the primary endpoint. Platelet counts ≥ 50 × 109/L or ≥ 30 × 109/L and doubling from baseline without rescue therapy were sustained for a mean 9.3 weeks. 11 (42%) LTE-eligible patients were ongoing with median LTE platelet > 80 × 109/L. Three (12%) patients received rescue medication during main treatment, none in LTE. Clinically meaningful improvements were observed in fatigue and women's health. With a median treatment duration of 167 days (main treatment), 16 (62%) patients had ≥ 1 treatment-related adverse event (AE), mainly grade 1, including diarrhea (35%), headache (23%), and nausea (15%). There was no treatment-related grade ≥ 2 bleeding/thrombotic events/infections, serious AE, or death. Rilzabrutinib continues to demonstrate durable platelet responses with favorable safety profile in previously treated ITP patients. Trial Registration: NCT03395210, EudraCT 2017-004012-19.

Desialylation and Apoptosis in Immune Thrombocytopenia: Implications for Pathogenesis and Treatment

Immune thrombocytopenia (ITP) is an autoimmune disease in which platelet autoantibodies play a significant role in its pathogenesis. Regulatory T cell dysfunction and T cell-mediated cytotoxicity also contribute to thrombocytopenia. Current therapies are directed towards immune suppression and modulation as well as stimulation of platelet production with thrombopoietin receptor agonists. Additional mechanisms of the pathogenesis of ITP have been suggested by recent experimental data. One of these processes, known as desialylation, involves antibody-induced removal of terminal sialic acid residues on platelet surface glycoproteins, leading to hepatic platelet uptake and thrombocytopenia. Apoptosis, or programmed platelet death, may also contribute to the pathogenesis of ITP. The extent of the impact of desialylation and apoptosis on ITP, the relative proportion of patients affected, and the role of antibody specificity are still the subject of investigation. This review will discuss both historical and new evidence of the influence of desialylation and apoptosis in the pathogenesis of ITP, with an emphasis on the clinical implications of these developments. Further understanding of both platelet desialylation and apoptosis might change current clinical practice and improve patient outcomes.

Preeclampsia: A comprehensive review

Preeclampsia (PE) is a life-threatening disease of pregnancy and a prominent cause of neonatal and maternal mortality and morbidity. PE affects approximately 5-10% of pregnancies worldwide, posing significant risks to perinatal and maternal health. It is characterized by a variety of interconnected pathological cascades contributing to the stimulation of intravascular inflammation, oxidative stress (OS), endothelial cell activation, and syncytiotrophoblast stress that converge on a common pathway, ultimately resulting in disease progression. The present study was designed and executed to review the existing scientific literature, specifically focusing on the etiology (gestational diabetes mellitus and maternal obesity, insulin resistance, metabolic syndrome, maternal infection, periodontal disease, altered microbiome, and genetics), clinical presentations (hypertension, blood disorders, proteinuria, hepatic dysfunction, renal dysfunction, pulmonary edema, cardiac dysfunction, fetal growth restrictions, and eclampsia), therapeutic clinical biomarkers (creatinine, albuminuria, and cystatin C) along with their associations and mechanisms in PE. In addition, this study provides insights into the potential of nanomedicines for targeting these mechanisms for PE management and treatment. Inflammation, OS, proteinuria, and an altered microbiome are prominent biomarkers associated with progression and PE-related pathogenesis. Understanding the molecular mechanisms, exploring suitable markers, targeted interventions, comprehensive screening, and holistic strategies are critical to decreasing the incidence of PE and promoting maternal-fetal well-being. The present study comprehensively reviewed the etiology, clinical presentations, therapeutic biomarkers, and preventive potential of nanomedicines in the treatment and management of PE.

Novel treatments for immune thrombocytopenia: targeting platelet autoantibodies

INTRODUCTION

Immune thrombocytopenia (ITP) is an acquired autoimmune disorder characterized by low platelets and an increased risk of bleeding. Platelet autoantibodies target major platelet glycoproteins and cause Fc-mediated platelet destruction in the spleen and reticuloendothelial systems. As mechanisms of disease, platelet autoantibodies are important therapeutic targets. Neonatal Fc receptor (FcRn) antagonists are a new class of therapeutics that reduce the half-life of immunoglobulin G including pathogenic platelet autoantibodies. Spleen tyrosine kinase (Syk) inhibitors interfere with Fc-mediated platelet clearance. Bruton's tyrosine kinase (BTK) inhibitors and B-cell activating factor (BAFF) inhibitors reduce antibody production. The efficacy of these targeted therapies provides new support for the role of platelet autoantibodies in pathogenesis of ITP even these antibodies can be difficult to detect.

AREAS COVERED

This review includes an in-depth exploration of the pathophysiologic mechanisms of ITP, focusing on autoantibodies. Treatments outlined in this review include a) FcRn antagonists, b) complement inhibitors, c) B-cell directed therapies such as BTK inhibitors, and anti-BAFF agents, d) Syk inhibitors, e) plasma-cell directed therapies, and f) novel cellular therapeutic products.

EXPERT OPINION

Platelet autoantibodies are often elusive in ITP, yet novel treatments targeting this pathway reinforce their role in the pathogenesis of this autoimmune platelet disorder.

The early and rapid response to daratumumab in children with chronic refractory immune thrombocytopenia from a referral single centre of China

Chronic refractory primary immune thrombocytopenia (CRITP) is currently defined as refractory to multiple therapeutic of second-line agents with or without splenectomy, faced with the threat of severe bleeding and challenging to obtain effective treatment. Although stable and effective drug therapy is needed, it is tough to find one. Daratumumab (Dara), an anti-CD38 monoclonal antibody presented the target cloned plasma cells in multiple myeloma, has also been reported to be effective in refractory autoimmune cytopenia in some case or series reports and ongoing clinical trials for adult patients with CRITP. Here, we report the early and durable response of Dara combination with avatrombopag in three CRITP patients (2 male and 1 female aged 12, 5 and 7 years, respectively) in our centre, with a follow-up period of more than 25 weeks. Before Dara, the duration of immune thrombocytopenia was 9, 1.4 and 4 years, respectively, a baseline platelet count of 4, 6, 9 × 109/L, the bleeding score was all above level 2 and the number of previous drugs was >3. The time to response (R: Plt ≥30 × 109/L with at least a twofold increase in the baseline count) of Dara was on Day 45, 6 and 4 and achieved complete response (CR: Plt ≥100 × 109/L) on Day 51, 6 and 8, the sustained response (SR: Plt >30 × 109/L following Dara at ≥75% of the platelet count assessment at follow-up end-point since the patient achieved response) was 48, 175 and 204 days with the follow-up time of 39.1, 25.9 and 29.7 weeks. The bleeding score decreased from grade 3 to grade 0 during follow-up. No significant treatment-related adverse events were found during follow-up. Dara combination with avatrombopag may be a safe and efficacious therapy for children with CRITP, but it needs to be further explored.

Treatment of Immune Thrombocytopenia: Contextualization from a Historical Perspective

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by an isolated decrease in platelet count and an increased risk of bleeding. The pathogenesis is complex, affecting multiple components of the immune system and causing both peripheral destruction of platelets and inadequate production in the bone marrow. In this article, we review the treatment of ITP from a historical perspective, discussing first line and second line treatments, and management of refractory disease.

Translating mechanisms into therapeutic strategies for immune thrombocytopenia (ITP): Lessons from clinical trials

Immune thrombocytopenia (ITP) is an autoimmune disorder that causes a significant reduction in peripheral blood platelet count. Fortunately, due to an increased understanding of ITP, there have been significant improvements in the diagnosis and treatment of these patients. Over the past decade, there have been a variety of proven therapeutic options available for ITP patients, including intravenous immunoglobulins (IVIG), Rituximab, corticosteroids, and thrombopoietin receptor agonists (TPO-RAs). Although the effectiveness of current therapies in treating more than two-thirds of patients, still some patients do not respond well to conventional therapies or fail to achieve long-term remission. Recently, a significant advancement has been made in identifying various mechanisms involved in the pathogenesis of ITP, leading to the development of novel treatments targeting these pathways. It seems that new agents that target plasma cells, Bruton tyrosine kinase, FcRn, platelet desialylation, splenic tyrosine kinase, and classical complement pathways are opening new ways to treat ITP. In this study, we reviewed the pathophysiology of ITP and summarized updates in this population's management and treatment options. We also took a closer look at the 315 ongoing trials to investigate their progress status and compare the effectiveness of interventions. May our comprehensive view of ongoing clinical trials serve as a guiding beacon, illuminating the path towards future trials of different drugs in the treatment of ITP patients.

New insights into the glycobiology of immune thrombocytopenia

PURPOSE OF REVIEW

The platelet surface harbors a lush forest of glycans (carbohydrate polymers) attached to membrane proteins and lipids. Accumulating evidence suggests that these glycans may be relevant to the pathophysiology of immune thrombocytopenia (ITP). Here, we critically evaluate data that point to a possible role for loss of sialic acid in driving platelet clearance in ITP, comment on the potential use of neuraminidase inhibitors for treatment of ITP, and highlight open questions in this area.

RECENT FINDINGS

Multiple lines of evidence suggest a role for loss of platelet sialic acid in the pathophysiology of thrombocytopenia. Recent work has tested the hypothesis that neuraminidase-mediated cleavage of platelet sialic acid may trigger clearance of platelets in ITP. Some clinical evidence supports efficacy of the viral neuraminidase inhibitor oseltamivir in ITP, which is surprising given its lack of activity against human neuraminidases.

SUMMARY

Further study of platelet glycobiology in ITP is necessary to fill key knowledge gaps. A deeper understanding of the roles of platelet glycans in ITP pathophysiology will help to guide development of novel therapies.

Rilzabrutinib versus placebo in adults and adolescents with persistent or chronic immune thrombocytopenia: LUNA 3 phase III study

Background

Immune thrombocytopenia (ITP) is characterized by primarily autoantibody-mediated platelet destruction and impaired platelet production resulting in thrombocytopenia and an increased risk of bleeding. Other manifestations include increased risk of thrombosis and diminished quality of life. Current treatment approaches are directed toward lowering the rate of platelet destruction or stimulating platelet production to prevent bleeding. Rilzabrutinib is an oral, reversible, potent Bruton tyrosine kinase inhibitor that was specifically designed to treat immune-mediated diseases and mediates its therapeutic effect through a dual mechanism of action: (1) inhibiting B-cell activation and (2) interrupting antibody-coated cell phagocytosis by Fc gamma receptor in spleen and liver. A 24-week dose-finding phase I/II study of rilzabrutinib in patients with ITP showed a 40% platelet response (⩾2 consecutive platelet counts of ⩾50 × 109/L and increase from baseline ⩾20 × 109/L without rescue medication use) and a well-tolerated safety profile with only grade 1/2 transient adverse events across dose levels.

Objectives

Assess the efficacy and safety of oral rilzabrutinib in adult and adolescent patients with persistent or chronic ITP.

Design

Rilzabrutinib 400 mg BID is being evaluated in the ongoing LUNA 3 multicenter, double-blind, placebo-controlled phase III study.

Methods and analysis

The primary endpoint is durable platelet response, defined as achieving platelet counts of ⩾50 × 109/L for at least two-thirds of ⩾8 available weekly scheduled platelet measurements during the last 12 weeks (including ⩾2 available measurements within the last 6 weeks) of the 24-week blinded treatment period in the absence of rescue therapy.

Ethics

Ethical guidelines and informed consent are followed.

Discussion

The LUNA 3 trial will further investigate rilzabrutinib's safety and efficacy in adult and adolescent patients, with the primary goal of addressing a major objective in treating patients with ITP: durability of platelet response.

Trail Registration

ClinicalTrials.gov NCT04562766: https://clinicaltrials.gov/ct2/show/NCT04562766; EU Clinical Trials Register EudraCT 2020-002063-60: https://www.clinicaltrialsregister.eu/ctr-search/search?query=2020-002063-60.

Primary and secondary immune thrombocytopenia (ITP): Time for a rethink

There are not many publications that provide a holistic view of the management of primary and secondary ITP as a whole, reflecting the similarities and differences between the two. Given the lack of major clinical trials, we believe that comprehensive reviews are much needed to guide the diagnosis and treatment of ITP today. Therefore, our review addresses the contemporary diagnosis and treatment of ITP in adult patients. With respect to primary ITP we especially focus on establishing the management of ITP based on the different and successive lines of treatment. Life-threatening situations, "bridge therapy" to surgery or invasive procedures and refractory ITP are also comprehensively reviewed here. Secondary ITP is studied according to its pathogenesis by establishing three major differential groups: Immune Thrombocytopenia due to Central Defects, Immune Thrombocytopenia due to Blocked Differentiation and Immune Thrombocytopenia due to Defective Peripheral Immune Response. Here we provide an up-to-date snapshot of the current diagnosis and treatment of ITP, including a special interest in addressing rare causes of this disease in our daily clinical practice. The target population of this review is adult patients only and the target audience is medical professionals.

Recent progress in ITP treatment

In this review, the recently approved drugs avatrombopag and fostamatinib, which were not extensively covered within 2019 international recommendations for ITP, will be discussed in some detail. Avatrombopag appears more convenient than eltrombopag as it does not require dietary restrictions or subcutaneous administration like romiplostim. However, data on quality of life (QoL) are lacking and the rate of thromboembolic events in exposed patients is not negligible. Efficacy of fostamatinib, an inhibitor of macrophagic activity, is supported by placebo-controlled trials in patients refractory to several therapies, including TPO-RA. While hypertension and diarrhea have been reported, only one minor thrombotic event occurred in 146 exposed patients. In addition, several new treatment combinations and new agents entered clinical investigation in recent years. In a UK trial, combining mycophenolate mofetil with corticosteroids as first line therapy was more effective than corticosteroids alone, but at the cost of worse QoL. No combination, including oseltamivir or all-trans retinoic acid or danazol, resulted in convincing evidence of superior efficacy and safety when used in first or later lines of treatment. Agents targeting specific mechanisms are also discussed: sutimlimab (complement inhibitor); rilzabrutinib (BTK inhibitor) and efgartigimod (modified Fc fragment inhibiting FcRn). Only efgartigimod has completed phase 3 investigation.

Warm autoimmune hemolytic anemia and the best treatment strategies

Warm autoimmune hemolytic anemia (wAIHA) is characterized by evidence of red blood cell (RBC) hemolysis and a direct antiglobulin test positive for IgG and sometimes complement. While varying with the extent of the compensatory increase in RBC production, symptoms of anemia predominate, as does jaundice, the latter often exacerbated by concurrent Gilbert's syndrome. Initial treatment with corticosteroids is highly effective, with over 85% of patients responding but with less than one-third maintaining that response upon weaning. Subsequent rituximab administration in those failing corticosteroids provides complete remission in over 75% of patients and may be long-lasting. Over 50% of patients failing rituximab respond to erythropoiesis-stimulating agents or immunosuppressive agents. Splenectomy is best deferred if possible but does offer long-term remission in over two-thirds of patients. A number of new treatments for wAIHA (fostamatinib, rilzabrutinib, and FcRn inhibitors) show promise. A treatment algorithm for wAIHA is proposed to avoid the excessive use of corticosteroids.

Deciphering transcriptome alterations in bone marrow hematopoiesis at single-cell resolution in immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disorder, in which megakaryocyte dysfunction caused by an autoimmune reaction can lead to thrombocytopenia, although the underlying mechanisms remain unclear. Here, we performed single-cell transcriptome profiling of bone marrow CD34+ hematopoietic stem and progenitor cells (HSPCs) to determine defects in megakaryopoiesis in ITP. Gene expression, cell-cell interactions, and transcriptional regulatory networks varied in HSPCs of ITP, particularly in immune cell progenitors. Differentially expressed gene (DEG) analysis indicated that there was an impaired megakaryopoiesis of ITP. Flow cytometry confirmed that the number of CD9+ and HES1+ cells from Lin-CD34+CD45RA- HSPCs decreased in ITP. Liquid culture assays demonstrated that CD9+Lin-CD34+CD45RA- HSPCs tended to differentiate into megakaryocytes; however, this tendency was not observed in ITP patients and more erythrocytes were produced. The percentage of megakaryocytes differentiated from CD9+Lin-CD34+CD45RA- HSPCs was 3-fold higher than that of the CD9- counterparts from healthy controls (HCs), whereas, in ITP patients, the percentage decreased to only 1/4th of that in the HCs and was comparable to that from the CD9- HSPCs. Additionally, when co-cultured with pre-B cells from ITP patients, the differentiation of CD9+Lin-CD34+CD45RA- HSPCs toward the megakaryopoietic lineage was impaired. Further analysis revealed that megakaryocytic progenitors (MkP) can be divided into seven subclusters with different gene expression patterns and functions. The ITP-associated DEGs were MkP subtype-specific, with most DEGs concentrated in the subcluster possessing dual functions of immunomodulation and platelet generation. This study comprehensively dissects defective hematopoiesis and provides novel insights regarding the pathogenesis of ITP.

Systemic lupus erythematosus-complicating immune thrombocytopenia: From pathogenesis to treatment

Immune thrombocytopenia (ITP) is a common hematological manifestation of systemic lupus erythematosus (SLE). The heterogeneity of its clinical characteristics and therapeutic responses reflects a complex pathogenesis. A better understanding of its pathophysiological mechanisms and employing an optimal treatment regimen is therefore important to improve the response rate and prognosis, and avoid unwanted outcomes. Besides glucocorticoids, traditional immunosuppressants (i.e. cyclosporine, mycophenolate mofetil) and intravenous immunoglobulins, new therapies are emerging and promising for the treatment of intractable SLE-ITP, such as thrombopoietin receptor agonists (TPO-RAs), platelet desialylation inhibitors(i.e. oseltamivir), B-cell targeting therapy(i.e. rituximab, belimumab), neonatal Fc receptor(FcRn) inhibitor, spleen tyrosine kinase(Syk) inhibitor and Bruton tyrosine kinase(BTK) inhibitor et al., although more rigorous randomized controlled trials are needed to substantiate their efficacy. In this review, we update our current knowledge on the pathogenesis and treatment of SLE-ITP.

Mechanism and Molecular Targets of Ejiao Siwu Decoction for Treating Primary Immune Thrombocytopenia Based on High-Performance Liquid Chromatograph, Network Pharmacology, Molecular Docking and Cytokines Validation

We explored the mechanisms and molecular targets of Ejiao Siwu Decoction (EJSW) for treating primary immune thrombocytopenia (ITP) using network pharmacology and molecular docking. Active compounds of EJSW were identified by high-performance liquid chromatography-diode array detector (HPLC-DAD) and high-performance liquid chromatography-mass spectrometry (HPLC-MS) and their targets were obtained from HERB and SwissTargetPrediction, and ITP targets were obtained from Comparative Toxicogenomics Database (CTD) and GeneCards. STRING and Cytoscape were used for protein-protein interaction (PPI) network analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses by WebGestalt yielded a gene-pathway network, Autodock molecular docking was applied to screen targets and active compounds, and cytokines were detected using a cytometric bead array (CBA) human inflammation kit. We identified 14 compounds and 129 targets, and 1,726 ITP targets. RAC-alpha serine/threonine-protein kinase (AKT1), tumour necrosis factor (TNF), interleukin-6 (IL6), caspase-3 (CASP3) and tumour suppressor protein (TP53) were core targets (nodes and edges). Functional annotation identified cofactor binding and coenzyme binding, and 20 significantly enriched pathways. Active compounds of EJSW were successfully docked with ITP targets. Tumour necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) were upregulated in ITP patients, vascular endothelial growth factor A (VEGF-A) and vascular endothelial growth factor D (VEGF-D) were downregulated, and EJSW treatment reversed these trends. EJSW may regulate key ITP targets based on the in silico analyses, and protect vascular integrity through AGE-RAGE signalling, complement and coagulation cascades, and VEGF signalling by downregulating TNF-α, IL-1β and other inflammatory factors.

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.

Treatment of drug-induced immune thrombocytopenias

Several therapeutic agents can cause thrombocytopenia by either immune-mediated or non-immune-mediated mechanisms. Non-immune-mediated thrombocytopenia is due to direct toxicity of drug molecules to platelets or megakaryocytes. Immune-mediated thrombocytopenia, on the other hand, involves the formation of antibodies that react to platelet-specific glycoprotein complexes, as in classic drug-induced immune thrombocytopenia (DITP), or to platelet factor 4, as in heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombotic thrombocytopenia (VITT). Clinical signs include a rapid drop in platelet count, bleeding or thrombosis. Since the patient's condition can deteriorate rapidly, prompt diagnosis and management are critical. However, the necessary diagnostic tests are only available in specialized laboratories. Therefore, the most demanding step in treatment is to identify the agent responsible for thrombocytopenia, which often proves difficult because many patients are taking multiple medications and have comorbidities that can themselves also cause thrombocytopenia. While DITP is commonly associated with an increased risk of bleeding, HIT and VITT have a high mortality rate due to the high incidence of thromboembolic complications. A structured approach to drug-associated thrombocytopenia/thrombosis can lead to successful treatment and a lower mortality rate. In addition to describing the treatment of DITP, HIT, VITT, and vaccine-associated immune thrombocytopenia, this review also provides the pathophysiological and clinical information necessary for correct patient management.

Treatment of chemotherapy-induced thrombocytopenia in patients with non-hematologic malignancies

Chemotherapy-induced thrombocytopenia (CIT) is a common complication of the treatment of non-hematologic malignancies. Many patient-related variables (e.g., age, tumor type, number of prior chemotherapy cycles, amount of bone marrow tumor involvement) determine the extent of CIT. CIT is related to the type and dose of chemotherapy, with regimens containing gemcitabine, platinum, or temozolomide producing it most commonly. Bleeding and the need for platelet transfusions in CIT are rather uncommon except in patients with platelet counts below 25x10⁹/L in whom bleeding rates increase significantly and platelet transfusions are the only treatment. Nonetheless, platelet counts below 70x10⁹/L present a challenge. In patients with such counts, it is important to exclude other causes of thrombocytopenia (medications, infection, thrombotic microangiopathy, post-transfusion purpura, coagulopathy and immune thrombocytopenia). If these are not present, the common approach is to reduce chemotherapy dose intensity or switch to other agents. Unfortunately decreasing relative dose intensity is associated with reduced tumor response and remission rates. Thrombopoietic growth factors (recombinant human thrombopoietin, pegylated human megakaryocyte growth and development factor, romiplostim, eltrombopag, avatrombopag and hetrombopag) improve pretreatment and nadir platelet counts, reduce the need for platelet transfusions, and enable chemotherapy dose intensity to be maintained. National Comprehensive Cancer Network guidelines permit their use but their widespread adoption awaits adequate phase III randomized, placebo-controlled studies demonstrating maintenance of relative dose intensity, reduction of platelet transfusions and bleeding, and possibly improved survival. Their potential appropriate use also depends on consensus by the oncology community as to what constitutes an appropriate pretreatment platelet count as well as identification of patient-related and treatment variables that might predict bleeding.

Evaluating fostamatinib disodium as a treatment option for immune thrombocytopenia in adult patients

INTRODUCTION

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder characterized by increased platelet destruction and decreased platelet production, leading to thrombocytopenia with or without bleeding manifestations. The majority of patients experiencing treatment need will eventually need secondary treatment following first line therapy with steroids. In 2018, the oral spleen tyrosine kinase inhibitor fostamatinib received US Food and Drug Administration approval for ITP patients with an insufficient response to a previous treatment.

AREAS COVERED

This review outlines pharmacological characteristics of fostamatinib and provides an overview of its efficacy and safety results in phase II and III trials, followed by the expert opinion of the authors.

EXPERT OPINION

Increasing knowledge on the role of different players and mechanisms in the pathophysiology of autoimmune disorders in general and of ITP in particular, has led to the development of several new treatment options, as illustrated by the introduction of fostamatinib in the treatment of ITP. However, lacking direct comparison with other recent treatment options (in particular thrombopoietin receptor agonists), its use should be evaluated critically taking into account the unique toxicity and potential drug-drug interaction profile.