Assessment of thrombotic risk during long-term treatment of immune thrombocytopenia with fostamatinib

Long-term safety and efficacy of fostamatinib in Japanese patients with primary immune thrombocytopenia

Fostamatinib had superior efficacy to a placebo and acceptable safety profiles for at least 1 year in a phase 3 study of Japanese patients with primary immune thrombocytopenia. Here, we report the 3-year safety and efficacy of fostamatinib in that study. Data from 33 patients who received at least one dose of fostamatinib were analyzed. A platelet response > 50,000/µL (at two consecutive visits at least 28 days apart while receiving fostamatinib) was achieved in 16 patients (48%). The median total duration of a platelet response > 50,000/µL was 589 (range: 106-1003) days. Gastrointestinal disorders, such as diarrhea, hypertension, and hepatic enzyme elevation, were the most common fostamatinib-related adverse events. Most events occurred within 12 weeks of treatment. No thromboembolisms, treatment-related infections, or moderate or severe treatment-related bleeding events were observed. In summary, this extension study of a clinical trial found a sustained platelet response without new safety signals during 3-year treatment with fostamatinib.

Analysis of Risk Factors and the Establishment of a Predictive Model for Thrombosis in Patients with Immune Thrombocytopenia

OBJECTIVES

To explore the risk factors for thrombi occurring in patients with immune thrombocytopenia (ITP) and establish a risk prediction model to better predict the risk of thrombosis in patients with ITP.

METHODS

We retrospectively analyzed 350 ITP patients who had been hospitalized in the First People's Hospital of Yunnan Province between January 2024 and June 2024. For all patients, we recorded demographic characteristics and clinical data, analyzed the risk factors for thrombosis in ITP patients and then developed a risk prediction model.

RESULTS

Stepwise logistic regression analysis indicated that a high D-dimer level, a low PC (platelet count) and a high Padua score were independent risk factors for thrombosis in ITP patients. According to multivariate analysis, a predictive model for thrombus risk showed that the area; the area under the ROC curve (AUC) was 0.673 (95% CI: 0.615-0.730) and the maximum Youden index, sensitivity and specificity were 0.272, 47.0% and 80.2%, respectively.

CONCLUSION

A high D-dimer level, low PC, and high Padua score were shown to be independent risk factors for thrombosis in ITP patients. Also, the study showed that these three risk factors might be used as a risk predictors for thrombosis in ITP patients to some extent.

Inpatient outcomes of NSTEMI among patients with immune thrombocytopenia: a propensity matched national study

Patients with immune thrombocytopenia (ITP) admitted for non-ST elevation myocardial infarction (NSTEMI) present a unique therapeutic challenge due to the increased risk of bleeding with antiplatelet and anticoagulation therapies. There is limited evidence studying hospital mortality and complications in this population. The study included a patient cohort from the 2018-2021 National Inpatient Sample database. Propensity score matched NSTEMI patients with and without ITP using a 1:1 matching ratio. Outcomes analyzed were in-hospital mortality, rates of diagnostic angiogram, percutaneous coronary intervention (PCI), acute kidney injury (AKI), congestive heart failure (CHF), cardiogenic shock, cardiac arrest, mechanical ventilation, tracheal intubation, ventricular tachycardia (VT), ventricular fibrillation (VF), major bleeding, need for blood and platelet transfusion, length of stay (LOS), and total hospitalization charges. A total of 1,699,020 patients met inclusion criteria (660,490 females [39%], predominantly Caucasian 1,198,415 (70.5%); mean [SD] age 67, [3.1], including 2,615 (0.1%) patients with ITP. Following the propensity matching, 1,020 NSTEMI patients with and without ITP were matched. ITP patients had higher rates of inpatient mortality (aOR 1.98, 95% CI 1.11-3.50, p 0.02), cardiogenic shock, AKI, mechanical ventilation, tracheal intubation, red blood cells and platelet transfusions, longer LOS, and higher total hospitalization charges. The rates of diagnostic angiogram, PCI, CHF, VT, VF, and major bleeding were not different between the two groups. Patients with ITP demonstrated higher odds of in-hospital mortality for NSTEMI and need for platelet transfusion with no difference in rates of diagnostic angiogram or PCI.

Fostamatinib effectiveness and safety for immune thrombocytopenia in clinical practice

ABSTRACT

Fostamatinib, a recently approved Syk inhibitor used in adult primary immune thrombocytopenia (ITP), has been shown to be safe and effective in this disorder. However, clinical trial results may not be similarly reproduced in clinical practice. Here, 138 patients with ITP (both primary and secondary) from 42 Spanish centers who had been treated with fostamatinib were evaluated prospectively and retrospectively. The median age of our cohort (55.8% women) was 66 years (interquartile range [IQR], 56-80). The median time since ITP diagnosis at fostamatinib initiation was 51 months (IQR, 10-166). The median number of therapies before fostamatinib initiation was 4 (IQR, 2-5), including eltrombopag (76.1%), romiplostim (57.2%), and IV immunoglobulins (44.2%). Fifty-eight patients (42.0%) had signs/symptoms of bleeding in the month before treatment initiation. Seventy-nine percent of patients responded to fostamatinib with 53.6% complete responses (platelet count > 100 × 109/L). Eighty-three patients (60.1%) received fostamatinib monotherapy, achieving a high response rate (85.4%). The proportion of time in response during the 27-month period examined was 83.3%. The median time to platelet response was 11 days (IQR, 7-21). Sixty-seven patients (48.5%) experienced adverse events, mainly grade 1 to 2; the commonest of which were diarrhea (n = 28) and hypertension (n = 21). One patient had deep venous thrombosis, and one patient developed acute myocardial infarction. Fostamatinib was shown to be effective with good safety profile in patients with primary and secondary ITP across a wide age spectrum in this real-world study.

Fostamatinib for immune thrombocytopenic purpura in adult patients: A systematic review and meta-analysis

Immune thrombocytopenic purpura (ITP) is an immune disorder characterized by thrombocytopenia. Fostamatinib is an orally administered spleen tyrosine kinase inhibitor intended to treat refractory ITP. To evaluate the efficacy and safety of fostamatinib as a subsequent-line therapy for ITP in adults. We searched four electronic databases for primary studies of any design. Primary efficacy outcomes included proportions of patients achieving overall (≥30 × 109 cells/L), partial (≥50 × 109 cells/L), and stable (as defined in original studies) platelet response. Safety outcomes included rescue medication use and other adverse events. We used narrative synthesis and Mantel-Haenszel random effect meta-analysis to summarize results. Our systematic review included 11 studies for analyses (n = 722). Weighted mean proportions of patients achieving overall, partial, and stable responses with fostamatinib treatment were 0.70 [0.62, 0.76], 0.48 [0.36, 0.61], and 0.28 [0.16, 0.44], respectively. Fostamatinib was favored over placebo for partial (relative risk [RR] = 3.04, 95% confidence interval [CI] [1.53, 6.06]) and stable (RR = 6.43, 95% CI [1.58, 26.23]) responses. Patients on fostamatinib required less rescue medication and were more likely to experience hypertension. Fostamatinib is a viable subsequent-line therapy option for refractory ITP. Given the heterogeneous data and large number of small studies, these results should be interpreted cautiously.

Post-marketing safety surveillance of fostamatinib: an observational, pharmacovigilance study leveraging FAERS database

OBJECTIVE

Fostamatinib, an FDA-approved oral small-molecule spleen tyrosine kinase (SYK) inhibitor, is used to treat thrombocytopenia in adults with chronic immune thrombocytopenia (ITP) who have not responded to previous treatments. However, comprehensive safety data is lacking. This study uses the FDA Adverse Event Reporting System (FAERS) database to explore real-world adverse events (AEs) related to fostamatinib, aiming to inform its clinical use.

METHODS

The FAERS database was retrospectively queried to extract reports associated with fostamatinib from 2019 to 2023. To identify and evaluate potential AEs in patients receiving fostamatinib, various disproportionality analyses such as the reporting odds ratio (ROR), the proportional reporting ratio (PRR), the Bayesian confidence propagation neural network (BCPNN), and the multi-item gamma Poisson shrinker (MGPS) were employed.

RESULTS

A total of 23 AE signals were included in our analysis. Among them, hypertension, blood pressure increase, blood pressure abnormality, hepatic enzyme increase, and diarrhea were consistent with the common AEs described for fostamatinib in clinical trials. In addition, unexpected serious AEs were detected including cerebral thrombosis and necrotizing soft tissue infection. The median time to onset of fostamatinib-related AEs was 86 days.

CONCLUSION

Our investigation revealed several possibly emergent safety concerns associated with fostamatinib in real-world clinical practice, which might provide essential vigilance evidence for clinicians and pharmacists to manage the safety issues of fostamatinib.

The 2022 review of the 2019 American Society of Hematology guidelines on immune thrombocytopenia

ABSTRACT

The 2019 American Society of Hematology (ASH) guidelines for immune thrombocytopenia (ITP) included recommendations on the management of adults (recommendations 1-9) and children (recommendations 10-21) with primary ITP . We describe here the results of a review of the 2019 guidelines by a working group of experts requested by ASH to inform decision-making about the need for and timing of a guideline revision. An updated Medline and Embase search applied the same search terms as in the 2019 ASH guidelines, limited to systematic reviews and clinical trials, from May 2017 to July 2022. There were 193 studies identified, 102 underwent abstract reviews, and 54 full reviews. Each study was assessed based on relevance to the previous recommendation with regard to the population, prioritized outcomes, new outcomes, and study design. Reviewers assessed if the data would change the strength or the directionality of the existing recommendation or merit development of a new recommendation. Based on this review, the ASH Committee on Quality endorsed a focused update on second-line management for adults with ITP. In addition, there will be continued annual monitoring and reviewing of the 2019 ASH guidelines on ITP in full to evaluate when there is sufficient new evidence to warrant additional revisions.

Splenomegaly and Response to Splenectomy in Immune Thrombocytopenia

Background: Immune thrombocytopenia (ITP) is an acquired autoimmune disorder affecting patients of all ages and backgrounds. While current standards favor medical therapy in the frontline setting, splenectomy remains an integral part of treatment in refractory cases. Ideal parameters for patient selection for surgery remain elusive. Methods: Data for 40 adult patients undergoing splenectomy for ITP at a large urban center between 1 January 2010 and 1 July 2021 were collected and analyzed. Results: Most patients underwent uneventful laparoscopic splenectomy (95%). Complete or partial response at the time of last follow-up occurred in most patients (92.5%), with 60.0% requiring no additional medical therapy following surgery. Thrombosis was the predominant adverse event and the leading cause of death for two patients. Age and presence of splenomegaly appear to be associated with response to splenectomy. Conclusions: Splenectomy remains an effective therapy for selected patients with ITP. Predictors of positive response to splenectomy, such as younger age and the presence of splenomegaly, may help inform clinicians during patient selection for therapy. With strict attention paid to postoperative thromboprophylaxis, the diminishing use of splenectomy may not be warranted.

Treatment with fostamatinib in patients with immune thrombocytopenia: Experience from the Andalusian region in Spain-The Fostasur Study

Immune thrombocytopenia (ITP) is characterized by low platelet counts (PLTs) and an increased risk of bleeding. Fostamatinib, a spleen tyrosine kinase inhibitor, has been approved as a second-line treatment for ITP. Real-world data on fostamatinib are lacking. This observational, retrospective, multicentre study, conducted in the Andalusia region of Spain, evaluated 44 adult primary ITP patients (47.7% female; median age 58 years; newly diagnosed ITP 6.8%; persistent 13.6%; chronic 79.5%; median four prior treatments) after ≥ 4 weeks of fostamatinib therapy. The median PLT at the initiation of fostamatinib was 15 × 109/L. Common reasons for starting fostamatinib were refractoriness or intolerance to prior therapy, oral medication preference, history of thrombosis and cardiovascular risk. Dosing was individualized based on efficacy and tolerance. After 2 weeks, global response rate was 56.8% (response and complete response). Response rates were 70.5%, 62.5% and 64% at 4 weeks, 12 weeks and at the end of the study respectively. Adverse events were mild, and no patients discontinued as a result. This real-world study demonstrated a response rate similar to fostamatinib as seen in the pivotal clinical trials while including newly diagnosed patients and allowing for individualized dosing.

A practical guide to the management of immune thrombocytopenia co-existing with acute coronary syndrome

Introduction

Immune thrombocytopenia (ITP) management with co-existing acute coronary syndrome (ACS) remains challenging as it requires a clinically relevant balance between the risk and outcomes of thrombosis and the risk of bleeding. However, the literature evaluating the treatment approaches in this high-risk population is scarce.

Methods and Results

In this review, we aimed to summarize the available literature on the safety of ITP first- and second-line therapies to provide a practical guide on the management of ITP co-existing with ACS. We recommend holding antithrombotic therapy, including antiplatelet agents and anticoagulation, in severe thrombocytopenia with a platelet count < 30 × 109/L and using a single antiplatelet agent when the platelet count falls between 30 and 50 × 109/L. We provide a stepwise approach according to platelet count and response to initial therapy, starting with corticosteroids, with or without intravenous immunoglobulin (IVIG) with a dose limit of 35 g, followed by thrombopoietin receptor agonists (TPO-RAs) to a target platelet count of 200 × 109/L and then rituximab.

Conclusion

Our review may serve as a practical guide for clinicians in the management of ITP co-existing with ACS.

Endovascular treatment of renal vein thrombosis in a young patient with lung transplant

Spontaneous renal vein thrombosis is a rare entity. A 28-year-old woman with a history of a double-lung transplant was admitted with flank pain and found to have acute kidney injury. A magnetic resonance venogram demonstrated isolated left renal vein thrombosis with extension into the inferior vena cava. Initial management with therapeutic anticoagulation and hydration was unsuccessful. Thus, pharmacochemical thrombectomy was performed. A temporary suprarenal inferior vena cava filter was placed for intraoperative pulmonary prophylaxis. The patient's renal function returned to baseline and remained normal 13 months later. Early incorporation of percutaneous pharmacomechanical thrombectomy can improve renal function when medical therapy alone is unsuccessful.

Thrombosis in patients with immune thrombocytopenia: incidence, risk, and clinical outcomes

Background

There is evidence that patients with immune thrombocytopenia (ITP) are at increased risk of thrombosis. However, the association of clinical- and treatment-related factors with thrombosis remains controversial.

Objectives

To evaluate the incidence and impact of risk factors for arterial and venous thromboembolism (VTE) in patients with ITP and characterize the clinical features and management of patients.

Methods

We performed a retrospective cohort study (January 1, 2011, to October 30, 2022) of adult patients diagnosed with ITP from an Australian tertiary hospital. The incidence rates of thrombosis were calculated in terms of person-years of follow-up. Multiadjusted Cox regression was used to estimate associations.

Results

A total of 220 patients with 1365 person-years of follow-up since ITP diagnosis revealed 26 (11.8%) patients with a total of 37 thrombosis events, 29 (78%) VTE and 8 (22%) arterial thromboembolism (ATE). The incidence rate of thrombosis was 2.71 (95% CI, 1.97-3.72) (0.66 [95% CI, 0.33-1.26] for arterial thromboembolism and 2.05 [95% CI, 1.42-2.95] for VTE) per 100 person-years. Mean age and median time to first thrombosis diagnosis was 56 and 2.13 years, respectively. Age, secondary ITP, lines of therapy, thrombosis risk factors, and thrombopoietin receptor agonist therapy were independently associated with thrombosis. Almost all patients (25 of 26, [96%]) had good ITP disease control prior to thrombosis diagnosis, and antithrombotic therapy was deliverable and well tolerated.

Conclusion

Diagnosis of thrombosis in patients with ITP, while infrequent, is of clinical significance. We identified from a heterogeneous real-world cohort that older patients with multiply-treated secondary ITP receiving thrombopoietin receptor agonists are at the highest risk.

Addressing thrombosis concerns in immune thrombocytopenia: the role of fostamatinib in immune thrombocytopenia management

INTRODUCTION

Immune thrombocytopenia (ITP), a disease that commonly presents with an increased risk of bleeding, can also paradoxically produce an increased risk of thromboembolic events. The risk of thromboembolism can be associated with patient-related factors (e.g. co-morbidities, age and history of thrombosis), disease-related factors (e.g. a greater proportion of younger, more reactive platelets, and the presence of microparticles and pro-inflammatory cytokines) and treatment-related factors (e.g. splenectomy, thrombopoietin receptor agonists, and IVIg).

AREAS COVERED

Aspects of the pathophysiology of ITP and the effects of treatment are discussed with emphasis on individualizing treatment based on the patient's thromboembolic risk, treatment options and preferences.

EXPERT OPINION

An increased understanding of the pathophysiology of ITP has led to the development of new agents such as fostamatinib, a spleen tyrosine kinase inhibitor. Further research into the factors contributing to the risks for bleeding and thromboembolic events can contribute to the development of more specific therapies for ITP and allow greater individualization of therapy based on each patient's medical history and clinical status.

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.

Current Concepts in the Diagnosis and Management of Adult Primary Immune Thrombocytopenia: Our Personal View

Primary immune thrombocytopenia (ITP) is an acquired blood disorder that causes a reduction in circulating platelets with the potential for bleeding. The incidence of ITP is slightly higher in adults and affects more women than men until 60 years, when males are more affected. Despite advances in basic science, primary ITP remains a diagnosis of exclusion. The disease is heterogeneous in its clinical behavior and response to treatment. This reflects the complex underlying pathophysiology, which remains ill-understood. Platelet destruction plays a role in thrombocytopenia, but underproduction is also a major contributing factor. Active ITP is a proinflammatory autoimmune disease involving abnormalities within the T and B regulatory cell compartments, along with several other immunological abnormalities. Over the last several years, there has been a shift from using immunosuppressive therapies for ITP towards approved treatments, such as thrombopoietin receptor agonists. The recent COVID-19 pandemic has hastened this management shift, with thrombopoietin receptor agonists becoming the predominant second-line treatment. A greater understanding of the underlying mechanisms has led to the development of several targeted therapies, some of which have been approved, with others still undergoing clinical development. Here we outline our view of the disease, including our opinion about the major diagnostic and therapeutic challenges. We also discuss our management of adult ITP and our placement of the various available therapies.

An obvious antinomy, superior sagittal sinus thrombosis in a patient with immune thrombocytopenia: Case report and a review of literatures

RATIONALE

Immune thrombocytopenia (ITP) is an autoimmune disease with an increased risk of bleeding. However, in recent years, it has been reported that patients with this hemorrhagic disease have the risk of thrombosis and embolism.

PATIENT CONCERNS AND DIAGNOSIS

The patient, in this case, was a young female who was diagnosed with ITP. When the platelet count was low, she had skin, mucosa, internal organs, and intracranial hemorrhage. In the process of ITP and hemostatic treatment, superior sagittal sinus thrombosis occurred when she was still bleeding.

INTERVENTIONS

She was given treatments for reducing intracranial pressure and controlling epilepsy.

OUTCOMES

And then the embolectomy operation failed. It was suggested in this case that ITP patients with severe thrombocytopenia and bleeding tendency also have a risk of having thrombotic disease. We reviewed literatures regarding the mechanism of the simultaneous occurrence of 2 antinomy diseases and cerebral venous thrombosis.

LESSONS

There are many factors for ITP patients to have thrombosis involving ITP itself, its treatment and the patients' constitution, medical history, and former medication. ITP is not only a hemorrhagic disease but also a thrombotic disease. Clinicians should be alert to the risk of thrombotic diseases in ITP treatment. Therefore thrombus monitoring and screening should be carried out, and early prevention or appropriate anticoagulant treatment should be selected, especially for patients with high risk.

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.

Fostamatinib for the treatment of Japanese patients with primary immune thrombocytopenia: A phase 3, placebo-controlled, double-blind, parallel-group study

Fostamatinib, a spleen tyrosine kinase inhibitor, has been approved for the treatment of chronic primary immune thrombocytopenia (ITP) in the United States, Canada and some European countries. We conducted a phase 3, placebo-controlled, double-blind, parallel-group study to evaluate the efficacy and safety of fostamatinib in Japanese patients with primary ITP. Thirty-four patients were randomised to fostamatinib (n = 22) or placebo (n = 12) at 100-150 mg twice a day for 24 weeks. Stable responses (platelet ≥50 000/μl at ≥4 of the 6 visits from weeks 14 to 24) were observed in eight (36%) patients on fostamatinib and in none of the patients on placebo (p = 0.030). Overall responses (platelet ≥50 000/μl at ≥1 of the 6 visits from weeks 2 to 12) were seen in 10 (45%) patients on fostamatinib and in none of the patients on placebo (p = 0.006). Patients on fostamatinib required rescue medication less often and experienced fewer bleeding symptoms than patients on placebo. Adverse events observed were mild or moderate and were manageable. No new safety signals were identified in Japanese patients with ITP.

Use and positioning of fostamatinib in the management of primary chronic immune thrombocytopenia: an Italian expert opinion

Fostamatinib, a spleen tyrosine kinase (Syk) inhibitor, represents a new therapeutic opportunity for patients with immune thrombocytopenia (ITP) in Europe and Italy. However, the positioning of this drug in patient's therapeutic sequence is undefined within the most recent international guidelines. The conclusions from a consensus meeting between Italian experts, whose task was to outline the profile of the ideal candidate to receive fostamatinib, are reported here. A modified Delphi methodology was used to achieve shared statements, which were reported in a narrative form. In particular, the panelists examined the strengths and weaknesses of the registration studies in terms of clinical outcomes, the safety profile of fostamatinib, the drug's impact on the quality of life of patients with chronic ITP, and the potential benefits of its use in the pandemic era. Although the experience with thrombopoietin receptor agonists (TPO-RAs) and the amount of data from real-world studies suggest the preferential use of these drugs as a second-line treatment in most patients, the absence of an increased thrombotic risk in the clinical trials could make fostamatinib a reasonable choice in patients with an increased risk of vascular events. An unstable platelet count during TPO-RAs might also justify a switch to the Syk inhibitor, which is more likely to stabilize the platelet count in responders. Fostamatinib may be preferred to immunosuppressors during the SARS-CoV-2 pandemic, in patients at infectious risk, or in case of contraindication to splenectomy. Finally, the novel mechanism of action makes it an attractive drug in multi-refractory patient.

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.

Safety and Efficacy of Tyrosine Kinase Inhibitors in Immune Thrombocytopenic Purpura: A Systematic Review of Clinical Trials

Immune thrombocytopenic purpura (ITP) is an acquired antibody or cell-mediated platelet damage or decreased platelet production. Steroids, IV immunoglobulins (IVIG), and Rho-anti-D antibodies are the commonly used initial treatments for ITP. However, many ITP patients either do not respond or do not maintain a response to initial therapy. Splenectomy, rituximab, and thrombomimetics are the commonly used second-line treatment. More treatment options include tyrosine kinases inhibitors (TKI), including spleen tyrosine kinase (Syk) and Bruton's tyrosine kinase (BTK) inhibitors. This review aims to assess the safety and efficacy of TKIs. Methods: Literature was searched on PubMed, Embase, WOS, and clinicaltrials.gov using keywords, "tyrosine kinase" and "idiopathic thrombocytopenic purpura". PRISMA guidelines were followed. Results: In total, 4 clinical trials were included with 255 adult patients with relapsed/refractory ITP. In all, 101 (39.6%) patients were treated with fostamatinib, 60 (23%) patients with rilzabrutinib, and 34 (13%) with HMPL-523. Patients treated with fostamatinib achieved a stable response (SR) and overall response (OR) in 18/101 (17.8%) and 43/101 (42.5%) of the patients, respectively, while SR and OR were achieved in 1/49 (2%) and 7/49 (14%) of the patients, respectively, in the placebo group. Patients treated with HMPL-523 (300 mg dose expansion) achieved an SR and OR in 5/20 (25%) and 11/20 (55%) of the patients, respectively, while SR and OR were achieved in 1/11 (9%) of the patients treated with the placebo. Patients treated with rilzabrutinib achieved an SR in 17/60 (28%) patients. Dizziness (1%), hypertension (2%), diarrhea (1%), and neutropenia (1%) were serious adverse events in fostamatinib patients. Rilzabrutinib or HMPL-523 patients did not require a dose reduction due to drug-related adverse effects. Conclusions: Rilzabrutinib, fostamatinib, and HMPL-523 were safe and effective in the treatment of relapsed/refractory ITP.

The Efficacy and Safety of Fostamatinib in Elderly Patients with Immune Thrombocytopenia: A Single-Center, Real-World Case Series

Fostamatinib is a small molecule spleen tyrosine kinase (Syk) inhibitor that was approved for the treatment of adult patients with immune thrombocytopenia (ITP) in second-line therapy. Syk inhibition prevents cytoskeletal rearrangements during phagocytosis, allowing platelet survival in ITP. However, fostamatinib treatment in elderly patients with ITP has not been well established. We performed a retrospective review of all elderly patients (age greater than or equal to 65 years) who had started on fostamatinib for the treatment of ITP at a single tertiary care centre to evaluate its efficacy and safety. Seven patients, median age 80 years (range 78–94), four women and three men, all of Caucasian background, with various comorbidities, started fostamatinib 100 mg orally twice daily as second or subsequent line therapy. Patients had a diagnosis of ITP for a median of 6 years (range approximately 6 months–30 years), had six comorbidities (range 2–14), and experienced 2 unique prior lines of ITP therapy (range 1 to 6). Over 1290 days of fostamatinib exposure, two patients required dose escalation to 150 mg orally twice daily, while five patients remained on the initial starting dose of 100 mg twice daily. The median platelet count at the time of initiating fostamatinib was 25 × 10⁹/L (range less than 10–193). The median time to response (defined as any first platelet count greater than or equal to 30 × 10⁹/L) was 19 days (range 0–181 days), with two patients responding rapidly (5 days and 19 days). Two patients required dose escalation and rescue therapy, and these same two patients discontinued fostamatinib after 175 days and 216 days of treatment. Treatment was tolerated in all patients with no thromboembolic events observed. One death was noted and unrelated to treatment. Overall, fostamatinib was effective and safe for the majority of these very elderly patients with ITP.

Current therapeutic strategies and perspectives in refractory ITP: What have we learned recently?

Immune thrombocytopenia (ITP) is an acquired autoimmune bleeding disorder featured by increased platelet destruction and deficient megakaryocyte maturation. First-line treatments include corticosteroids, intravenous immunoglobulin and intravenous anti-D immunoglobulin. Second-line treatments consist of rituximab, thrombopoietin receptor agonists and splenectomy. Although most patients benefit from these treatments, an individualized treatment approach is warranted due to the large heterogeneity among ITP patients. In addition, ITP patients may relapse and there remains a subset of patients who become refractory to treatments. The management of these refractory patients is still a challenge. This review aims to summarize emerging therapeutic approaches for refractory ITP in several categories according to their different targets, including macrophages, platelets/megakaryocytes, T cells, B cells, and endothelial cells. Moreover, current management strategies and combination regimens of refractory ITP are also discussed.

Antithrombotic Effects of Fostamatinib in Combination with Conventional Antiplatelet Drugs

New antithrombotic medications with less effect on haemostasis are needed for the long-term treatment of acute coronary syndromes (ACS). The platelet receptor glycoprotein VI (GPVI) is critical in atherothrombosis, mediating platelet activation at atherosclerotic plaque. The inhibition of spleen tyrosine kinase (Syk) has been shown to block GPVI-mediated platelet function. The aim of our study was to investigate if the Syk inhibitor fostamatinib could be repurposed as an antiplatelet drug, either alone or in combination with conventional antiplatelet therapy. The effect of the active metabolite of fostamatinib (R406) was assessed on platelet activation and function induced by atherosclerotic plaque and a range of agonists in the presence and absence of the commonly used antiplatelet agents aspirin and ticagrelor. The effects were determined ex vivo using blood from healthy volunteers and aspirin- and ticagrelor-treated patients with ACS. Fostamatinib was also assessed in murine models of thrombosis. R406 mildly inhibited platelet responses induced by atherosclerotic plaque homogenate, likely due to GPVI inhibition. The anti-GPVI effects of R406 were amplified by the commonly-used antiplatelet medications aspirin and ticagrelor; however, the effects of R406 were concentration-dependent and diminished in the presence of plasma proteins, which may explain why fostamatinib did not significantly inhibit thrombosis in murine models. For the first time, we demonstrate that the Syk inhibitor R406 provides mild inhibition of platelet responses induced by atherosclerotic plaque and that this is mildly amplified by aspirin and ticagrelor.

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.

In silico Analysis of Publicly Available Transcriptomics Data Identifies Putative Prognostic and Therapeutic Molecular Targets for Papillary Thyroid Carcinoma

Background

Purpose

Methods

Results

Conclusion

Investigational spleen tyrosine kinase (SYK) inhibitors for the treatment of autoimmune diseases

INTRODUCTION

Autoimmune diseases (ADs) are disorders induced by multiple inflammatory mediators, in which immune system attacks healthy tissues and triggers tissue injury. Targeted regulation of the activity of kinases that influence inflammation is one of the major therapies for ADs. Recently, investigational spleen tyrosine kinase (SYK) inhibitors have shown encouraging results in the ADs therapy.

AREAS COVERED

This article provides a background on autoimmune diseases and provides an update on investigational SYK inhibitors. This literature review was conducted by searching publications about investigational Spleen tyrosine kinase inhibitors in the treatment of ADs from experimental to clinical studies. The search terms used were SYK inhibitors, R406, fostamatinib (R788), P505-15 (PRT062607), entospletinib (GS-9973), R112, lanraplenib (GS-9876), cerdulatinib, R343, BAY-61-3606, GSK compound 143 (GSK143), R211, SKI-G-618, SKI-O-85, ER-27319, YM193306, RO9021 in conjunction with autoimmune disease using electronic databases including PubMed, EMBASE, MEDLINE and Google Scholar.

EXPERT OPINION

SYK inhibitors are promising drugs with unique advantages and acceptable tolerability and safety for the treatment of ADs. However, the difficulties in developing highly selective SYK inhibitors and the unknown effects are challenges. Long term and real-world data are essential to determine the risk-benefit ratio and true role of SYK inhibitors in the therapy of ADs.

Role of Tyrosine Kinase Syk in Thrombus Stabilisation at High Shear

Understanding the pathways involved in the formation and stability of the core and shell regions of a platelet-rich arterial thrombus may result in new ways to treat arterial thrombosis. The distinguishing feature between these two regions is the absence of fibrin in the shell which indicates that in vitro flow-based assays over thrombogenic surfaces, in the absence of coagulation, can be used to resemble this region. In this study, we have investigated the contribution of Syk tyrosine kinase in the stability of platelet aggregates (or thrombi) formed on collagen or atherosclerotic plaque homogenate at arterial shear (1000 s^-1). We show that post-perfusion of the Syk inhibitor PRT-060318 over preformed thrombi on both surfaces enhances thrombus breakdown and platelet detachment. The resulting loss of thrombus stability led to a reduction in thrombus contractile score which could be detected as early as 3 min after perfusion of the Syk inhibitor. A similar loss of thrombus stability was observed with ticagrelor and indomethacin, inhibitors of platelet adenosine diphosphate (ADP) receptor and thromboxane A₂ (TxA₂), respectively, and in the presence of the Src inhibitor, dasatinib. In contrast, the Btk inhibitor, ibrutinib, causes only a minor decrease in thrombus contractile score. Weak thrombus breakdown is also seen with the blocking GPVI nanobody, Nb21, which indicates, at best, a minor contribution of collagen to the stability of the platelet aggregate. These results show that Syk regulates thrombus stability in the absence of fibrin in human platelets under flow and provide evidence that this involves pathways additional to activation of GPVI by collagen.

Thrombocytopathy vs Platelet hyper-reactivity in COVID-19: diverse pathologies, disease outcomes and therapeutic implications

Coagulopathy is an evident complication of COVID-19 with predominance of a prothrombotic state. Platelet activation plays a key role. The terms "hyper-reactivity" and "hyperactivity" used in recent literature may not be clear or sufficient to explain the pathological events involved in COVID-related thrombosis (CRT). Inflammation may play a bigger role compared to thrombosis in COVID-related mortality because a smaller percentage of patients with COVID-19 die due to direct effects of thrombosis. Not all COVID-19 patients have thrombocytopenia and a few show thrombocytosis. We believe the platelet pathology is more complex than just activation or hyper-activation, particularly due to the platelets' role in inflammation. Understanding the pathology and consequences of platelets' role may help optimize management strategies and diminish CRT-associated morbidity and mortality. In this viewpoint report, we examine the published evidence of platelet hyper-reactivity in COVID-19 with a focused analysis of the key pathologies, diverse alterations, disease outcomes, and therapeutic targets. We believe that COVID-19 is a disease of inflammation and pathologic platelets, and based on the complexity and diverse pathologies, we propose the term "thrombocytopathy" as a more reflective term of the platelets' involvement in COVID-19. In our opinion, thrombocytopathy is the unpredictable pathologic alterations of platelets in function, morphology and number, caused by different factors with a variety of presentations.

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.