fostamatinib and Purpura--Thrombocytopenic--Idiopathic

Spleen tyrosine kinase (SYK) is an important regulatory molecule of signal transduction pathways involved in the pathogenesis of autoimmune diseases such as immune thrombocytopenia (ITP), and the SYK-signaling pathway has emerged as a potential target for the treatment of numerous diseases. The aim of this narrative review is to summarize the biological properties of SYK and its involvement in disease pathways, provide an update on SYK inhibitors in the treatment of ITP, and consider other potential applications. Fostamatinib, the only licensed SYK inhibitor to date, produces clinical response in ITP patients, including those who are refractory to other treatments. It appears to reduce the risk of thrombotic events and may therefore be a drug to consider for patients with an increased thrombotic risk. Encouraging results have also been obtained in the treatment of warm autoimmune hemolytic anemia. Several other SYK inhibitors have entered clinical trials for a range of indications, reflecting the ability of these drugs to affect multiple signaling pathways. SYK inhibitors have the potential to target several aspects of COVID-19 pathogenesis including thrombosis, without affecting normal hemostasis, and data from the first study of fostamatinib in COVID-19 are encouraging. It is hoped that ongoing trials in autoimmune indications other than ITP, as well as in hematological malignancies and other disorders, confirm the promise of SYK inhibitors.. Immune thrombocytopenia (ITP) is an autoimmune disease that usually happens when your immune system mistakenly attacks and destroys platelets, which are cells that help blood to clot. Individuals with ITP can experience easy or excessive bruising and bleeding. Scientists have identified that an enzyme called spleen tyrosine kinase (SYK) is involved in numerous biological processes that are associated with the immune system response, inflammation, and some types of cancer in humans. Therefore, it has become a target for new drugs which inhibit the action of SYK. In this review article, the authors provide a summary of the biological properties and actions of SYK and its involvement in various diseases, discuss information about drugs that have been developed as SYK inhibitors for the treatment of ITP, and consider other potential uses for drugs that inhibit SYK. Although several drugs are being developed, the only SYK inhibitor that is currently available for the treatment of ITP is a drug called fostamatinib. In patients with ITP, including those who no longer respond to other treatments, fostamatinib has been shown to improve platelet counts and reduce bleeding events. Researchers are also currently investigating the use of drugs that inhibit SYK, including fostamatinib, for the potential treatment of other diseases associated with inflammation (e.g. rheumatoid arthritis, COVID-19), autoimmunity (e.g. warm autoimmune hemolytic anemia), and blood cancers (e.g. lymphoma, chronic lymphocytic leukemia, and acute myeloid leukemia).

Topics: Aminopyridines; COVID-19; Humans; Oxazines; Protein Kinase Inhibitors; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Syk Kinase

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.

Topics: Clinical Trials as Topic; Humans; Purpura, Thrombocytopenic, Idiopathic; Quality of Life; Receptors, Fc; Recombinant Fusion Proteins; Thiazoles; Thrombopoietin

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.. 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.. 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.

Topics: Adult; Aminopyridines; Humans; Morpholines; Oxazines; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Thrombocytopenia

Fostamatinib is the first approved spleen tyrosine kinase inhibitor for chronic immune thrombocytopenia. This review summarizes the clinical development, pharmacokinetics, pharmacodynamics, drug-drug interactions, adverse events, and comprehensive analyses of fostamatinib. While integrating these findings, we discuss the fostering and improvement of fostamatinib for further clinical applications. Fostamatinib is designed as a prodrug and cleavage of its active moiety R406 in the intestine. As R406 is the major product in the blood, this review mainly discusses the pharmacokinetics and pharmacodynamics of R406. It is metabolized by cytochrome 3A4 and UGT1A9 in the liver and is dominantly excreted in feces after anaerobic modification by the gut microbiota. As fostamatinib and R406 strongly inhibit the breast cancer resistance protein, the interaction with those substrates, particularly statins, should be carefully monitored. In patients with immune thrombocytopenia, fostamatinib administration started at 100 mg twice daily, and most patients increased to 150 mg twice daily in the clinical trial. Although responders showed a higher R406 concentration than non-responders, the correlation between R406 exposure and achievement of the platelet count as a pharmacodynamic marker was uncertain in the pharmacokinetic/pharmacodynamic analysis. Additionally, R406 concentration was almost halved in patients with a heavy body weight; hence, the exposure-efficacy study for suitable dosing should be continued with post-marketing data. In contrast, the pharmacokinetic/pharmacodynamic analysis for exposure safety revealed that R406 exposure significantly correlated with the incidence of hypertension. Even though the influence of elevated exposure on other toxicities, including diarrhea and neutropenia, is still unclear, careful management is required with dose escalation to avoid toxicity-related discontinuation.

Topics: Aminopyridines; ATP Binding Cassette Transporter, Subfamily G, Member 2; Humans; Morpholines; Neoplasm Proteins; Oxazines; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines

Fostamatinib (Tavalisse

Topics: Aminopyridines; Chronic Disease; Clinical Trials, Phase III as Topic; Humans; Morpholines; Purpura, Thrombocytopenic, Idiopathic; Pyrimidines; Randomized Controlled Trials as Topic; Syk Kinase

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

Topics: Aminopyridines; Antibodies, Monoclonal, Humanized; COVID-19; Histocompatibility Antigens Class I; Humans; Immunosuppressive Agents; Morpholines; Protein Kinase Inhibitors; Purpura, Thrombocytopenic, Idiopathic; Pyrimidines; Receptors, Fc; Receptors, Thrombopoietin; SARS-CoV-2; Syk Kinase; Thiazoles; Thiophenes

Management of chronic immune thrombocytopenia (ITP) is going through a transition, with the main driving forces being a better understanding of the disease, recognition that platelet count is less important than bleeding symptoms, and the availability of new therapies. The heterogeneity of chronic ITP makes treatment challenging, and highlights the need for a personalized approach. A key aspect of tailored treatment is the availability of agents to target specific underlying pathophysiological mechanisms. In this review, we examine the evidence for orally bioavailable fostamatinib and its active moiety, tamatinib (R406), which has been approved for the treatment of chronic adult ITP. Fostamatinib inhibits FcR-triggered, Syk-dependent cytoskeletal rearrangement during phagocytosis and, as such, represents an active therapy targeting a previously unexplored mechanism of ITP pathogenesis.

Topics: Aminopyridines; Humans; Morpholines; Purpura, Thrombocytopenic, Idiopathic; Pyrimidines; Treatment Outcome

Fostamatinib is a spleen tyrosine kinase inhibitor recently approved for the treatment of chronic immune thrombocytopenia (ITP) in patients without adequate response to at least 1 prior line of therapy. This article reviews fostmatinib's mechanism of action and its clinical safety and efficacy in 2 industry-sponsored multicenter phase 3 randomized controlled trials in North America, Australia, and Europe (FIT1 and FIT2). Cost comparisons are discussed as well as the role of fostamatinib in relation to other options for chronic ITP.

Topics: Aminopyridines; Clinical Trials, Phase III as Topic; Humans; Morpholines; Oxazines; Protein Kinase Inhibitors; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines

Immune thrombocytopenia (ITP) is an acquired autoimmune disorder characterized by phagocytosis and destruction of autoantibody-coated platelets via spleen tyrosine kinase (Syk)-mediated signal transduction in macrophages. Effectiveness of existing therapies varies, and even leading treatments (e.g., IVIg, splenectomy, rituximab, thrombopoietic agents) do not provide optimal management for a substantial number of patients with chronic ITP. Fostamatinib disodium is an orally-bioavailable investigational agent being developed for treatment of primary persistent/chronic adult ITP. Fostamatinib inhibits FcR-triggered, Syk-dependent cytoskeletal rearrangement during phagocytosis. Promising findings have been described in several autoimmune diseases, including rheumatoid arthritis, and sustained responses with manageable adverse events observed with ongoing treatment in patients with heavily treated chronic ITP. Fostamatinib represents an active therapy targeting a previously unexplored mechanism of ITP pathogenesis.

Topics: Adult; Aminopyridines; Blood Platelets; Chronic Disease; Humans; Immunotherapy; Morpholines; Oxazines; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Recurrence; Signal Transduction; Syk Kinase

Rigel Pharmaceuticals are developing the spleen tyrosine kinase (SYK) inhibitor fostamatinib (TAVALISSE™) as a treatment for immune thrombocytopenia (ITP), autoimmune haemolytic anaemia and IgA nephropathy. Based on positive results in the phase III FIT clinical trial program, the drug was recently approved in the US as a treatment for thrombocytopenia in adult patients with chronic ITP who have had an insufficient response to a previous treatment. This article summarizes the milestones in the development of fostamatinib leading to this first approval.

Topics: Aminopyridines; Anemia, Hemolytic, Autoimmune; Drug Approval; Glomerulonephritis, IGA; Humans; Morpholines; Oxazines; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Syk Kinase; Treatment Outcome

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.

Topics: Double-Blind Method; East Asian People; Humans; Oxazines; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Treatment Outcome

Fostamatinib demonstrated efficacy in phase 3 trials of adults with immune thrombocytopenia (ITP). Post hoc analysis compared patients who received fostamatinib as second-line therapy (after steroids ± immunoglobulins) versus third-or-later-line therapy (after ≥2 prior lines of therapy including a second-line agent). Platelet responses ≥50 000/µl were observed in 25/32 (78%) second-line and 54/113 (48%) third-or-later-line patients. Bleeding events were less frequent in second-line (28%) versus third-or-later-line (45%) patients. Responses once achieved tended to be durable in both groups. The safety profile was similar in both groups. In this post hoc analysis, fostamatinib was more effective as second-line than third-or-later-line therapy for ITP.

Topics: Adult; Aged; Aged, 80 and over; Aminopyridines; Female; Humans; Male; Middle Aged; Morpholines; Oxazines; Platelet Count; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines

Two randomized, double-blind, placebo-controlled studies demonstrated responses (≥50 000/μL) to fostamatinib in adults with long-standing immune thrombocytopenia (ITP). The long-term safety and efficacy of fostamatinib were evaluated in a follow-on, open-label extension (OLE) study. Patients received double-blind fostamatinib in the randomized trials, and responders continued the same dose, 100 to 150 mg BID, in the OLE study. Nonresponders received 100 mg BID for 4 weeks and could escalate to 150 mg BID at week 4. Endpoints included stable response, platelet count ≥50 000/μL at 4/6 biweekly (randomized trials) or 2/3 monthly visits (OLE), and overall response, ≥1 platelet count ≥50 000/μL during weeks 1 to 12. A total of 146 patients received fostamatinib including 123 in the OLE study. Median treatment duration was 6.7 months. Baseline median ITP duration was 8 years and median platelet count was 16 000/μL; prior treatments included thrombopoietic (TPO) agents (47%), splenectomy (35%), and rituximab (32%). Twenty-seven (18%) patients achieved a stable response with median duration of >28 months and a median platelet count of 89 000/μL. Sixty-four (44%) patients achieved an overall response (including stable responders) with a median platelet count of 63 000/μL and a median response duration of >28 months. Twenty-four of 71 (34%) patients who had failed TPO agents achieved overall responses to fostamatinib. The most common adverse events (AEs) were diarrhea, hypertension, nausea, epistaxis, and abnormal liver function tests. Most AEs were mild/moderate and resolved or were managed with dose reduction, dose interruption, and/or secondary medication. Almost half of the patients achieved an overall response, and most of these maintained their responses for >2 years. No new or increased frequency of AEs was seen at up to 31 months of treatment.

Topics: Adult; Aged; Aged, 80 and over; Aminopyridines; Double-Blind Method; Female; Humans; Male; Middle Aged; Morpholines; Oxazines; Platelet Count; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Time Factors

Spleen tyrosine kinase (Syk) signaling is central to phagocytosis-based, antibody-mediated platelet destruction in adults with immune thrombocytopenia (ITP). Fostamatinib, an oral Syk inhibitor, produced sustained on-treatment responses in a phase 2 ITP study. In two parallel, phase 3, multicenter, randomized, double-blind, placebo-controlled trials (FIT1 and FIT2), patients with persistent/chronic ITP were randomized 2:1 to fostamatinib (n = 101) or placebo (n = 49) at 100 mg BID for 24 weeks with a dose increase in nonresponders to 150 mg BID after 4 weeks. The primary endpoint was stable response (platelets ≥50 000/μL at ≥4 of 6 biweekly visits, weeks 14-24, without rescue therapy). Baseline median platelet count was 16 000/μL; median duration of ITP was 8.5 years. Stable responses occurred in 18% of patients on fostamatinib vs. 2% on placebo (P = .0003). Overall responses (defined retrospectively as ≥1 platelet count ≥50 000/μL within the first 12 weeks on treatment) occurred in 43% of patients on fostamatinib vs. 14% on placebo (P = .0006). Median time to response was 15 days (on 100 mg bid), and 83% responded within 8 weeks. The most common adverse events were diarrhea (31% on fostamatinib vs. 15% on placebo), hypertension (28% vs. 13%), nausea (19% vs. 8%), dizziness (11% vs. 8%), and ALT increase (11% vs. 0%). Most events were mild or moderate and resolved spontaneously or with medical management (antihypertensive, anti-motility agents). Fostamatinib produced clinically-meaningful responses in ITP patients including those who failed splenectomy, thrombopoietic agents, and/or rituximab. Fostamatinib is a novel ITP treatment option that targets an important mechanism of ITP pathogenesis.

Topics: Adult; Aminopyridines; Blood Platelets; Chronic Disease; Humans; Morpholines; Oxazines; Platelet Count; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Splenectomy; Syk Kinase; Treatment Outcome

To determine whether inhibition of Syk would be useful in FcgammaR-dependent cytopenias such as immune thrombocytopenic purpura (ITP) or autoimmune hemolytic anemia, mouse models were used to evaluate efficacy of R406, an inhibitor of Syk function, in treating cytopenia. Both disease models responded favorably to treatment, with amelioration of ITP being more dramatic. Thus, phase 2 clinical trial was initiated to study the effects of Syk inhibition in humans with ITP. Sixteen adults with chronic ITP were entered into an open-label, single-arm cohort dose-escalation trial beginning with 75 mg and escalating as high as 175 mg twice daily. Doses were increased until a persistent response was seen, toxicity occurred, or 175 mg twice daily was reached. Eight patients achieved persistent responses with platelet counts greater than 50 x 10(9)/L (50 000 mm(3)) on more than 67% (actually 95%) of their study visits, including 3 who had not persistently responded to thrombopoietic agents. Four others had nonsustained responses. Mean peak platelet count exceeded 100 x 10(9)/L (100 000 mm(3)) in these 12 patients. Toxicity was primarily GI-related with diarrhea (urgency) and vomiting; 2 patients had transaminitis. In conclusion, inhibition of Syk was an efficacious means of increasing and maintaining the platelet count in half the patients with chronic refractory ITP. (ClinicalTrials.gov, no. NCT00706342).

Topics: Adult; Aged; Aged, 80 and over; Algorithms; Aminopyridines; Animals; Disease Models, Animal; Enzyme Inhibitors; Female; Humans; Intracellular Signaling Peptides and Proteins; Male; Mice; Middle Aged; Morpholines; Oxazines; Pilot Projects; Prodrugs; Protein-Tyrosine Kinases; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Syk Kinase; Treatment Outcome

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.

Topics: Adrenal Cortex Hormones; Adult; Aged; Aminopyridines; Combined Modality Therapy; Disease Management; Drug Substitution; Drug Tolerance; Elective Surgical Procedures; Female; Hemorrhage; Humans; Immunosuppressive Agents; Maintenance Chemotherapy; Male; Middle Aged; Morpholines; Preoperative Care; Purpura, Thrombocytopenic, Idiopathic; Pyrimidines; Randomized Controlled Trials as Topic; Receptors, Fc; Receptors, Thrombopoietin; Recombinant Fusion Proteins; Remission Induction; Rituximab; Splenectomy; Thrombopoietin; Young Adult

Care of patients with chronic immune thrombocytopenia (ITP) who are refractory to available treatments can be quite challenging. Fostamatinib, an oral Syk inhibitor, is the newest FDA-approved agent for ITP. Phase 3 clinical trials demonstrated an overall response in 43% of patients treated with fostamatinib and use for two years has been reported. Herein, we report two patients with long histories of ITP without lasting responses to numerous first-, second- and third-line therapies with prolonged responses to ongoing fostamatinib. This shows that patients unresponsive to other agents may respond to fostamatinib and can have sustained benefit.

Topics: Adult; Aged; Aminopyridines; Chronic Disease; Female; Humans; Morpholines; Oxazines; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines

Topics: Aminopyridines; Humans; Morpholines; Oxazines; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Thrombocytopenia

The pharmacology, pharmacokinetics, efficacy, safety, dosing and administration, and place in therapy of fostamatinib, a novel spleen tyrosine kinase inhibitor for the treatment of adult immune thrombocytopenia that has had an insufficient response to a previous treatment are summarized.. Fostamatinib is an oral inhibitor of spleen tyrosine kinase that is expressed on hematopoietic cells and plays a key role in the accelerated destruction of platelets through Fc-receptor activation. Fostamatinib is indicated for the treatment of adults with immune thrombocytopenia that has had an insufficient response to a previous treatment. In 2 parallel, identically designed, placebo-controlled Phase III trials, patients with persistent and chronic immune thrombocytopenia treated with fostamatinib demonstrated clinically meaningful responses in platelet counts with lower rates of moderate and severe bleeding-related adverse events. Overall, fostamatinib therapy is generally well tolerated; the most common adverse events reported in clinical trials were diarrhea, nausea, hypertension, liver function test elevations, and infection. Being primarily metabolized through the CYP3A4 pathway, fostamatinib is subject to drug-drug interactions and concomitant administration with strong CYP3A4 inhibitors or inducers can affect fostamatinib exposure.. Fostamatinib is a first-in-class spleen tyrosine kinase inhibitor approved for the treatment of adults with immune thrombocytopenia that has had an insufficient response to a previous treatment.

Topics: Administration, Oral; Aminopyridines; Blood Platelets; Clinical Trials, Phase III as Topic; Dose-Response Relationship, Drug; Humans; Morpholines; Oxazines; Platelet Count; Protein Kinase Inhibitors; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Receptors, Fc; Signal Transduction; Syk Kinase; Treatment Outcome

Topics: Aminopyridines; Clinical Trials, Phase III as Topic; Humans; Morpholines; Oxazines; Prodrugs; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Recurrence; Syk Kinase

Rigel Pharmaceuticals Inc is developing fostamatinib, a prodrug of the spleen tyrosine kinase (Syk) inhibitor R-406, for the potential treatment of autoimmune diseases such as rheumatoid arthritis (RA), idiopathic thrombocytopenic purpura (ITP) and B-cell lymphomas. Syk is a key mediator of Fc and B-cell receptor signaling in inflammatory cells, such as B-cells, mast cells, macrophages and neutrophils. Preclinical studies of R-406 or fostamatinib demonstrated a significant reduction in major inflammatory mediators such as TNFalpha, IL-1, IL-6 and IL-18, leading to reduced inflammation and bone degradation in models of RA. In a phase II clinical trial, fostamatinib treatment effectively improved American College of Rheumatology response rates in patients with RA. Preclinical studies and phase II trials also suggested the potential of using fostamatinib for the treatment of ITP and B-cell lymphomas, by increasing platelet counts and inducing response rates, respectively. Fostamatinib is orally bioavailable and was well tolerated in phase I and II trials, with the most common side effect being gastrointestinal symptoms. At the time of publication, phase II trials for fostamatinib were ongoing in patients with RA, ITP and B-cell lymphomas. The Syk inhibitor appears to be a promising therapeutic for immunological diseases, but further data are required to establish the efficacy and long-term safety of the drug in humans.

Topics: Aminopyridines; Arthritis, Rheumatoid; Clinical Trials as Topic; Drug Evaluation, Preclinical; Enzyme Inhibitors; Humans; Intracellular Signaling Peptides and Proteins; Lymphoma; Molecular Structure; Morpholines; Oxazines; Prodrugs; Protein-Tyrosine Kinases; Purpura, Thrombocytopenic, Idiopathic; Pyridines; Pyrimidines; Structure-Activity Relationship; Syk Kinase