Spleen tyrosine kinase inhibition in the treatment of autoimmune, allergic and autoinflammatory diseases

Identifying allergic-rhinitis-associated genes with random-walk-based method in PPI network

Allergic rhinitis is a common allergic disease with a complex pathogenesis and many unresolved issues. Studies have shown that the incidence of allergic rhinitis is closely related to genetic factors, and research on the related genes could help further understand its pathogenesis and develop new treatment methods. In this study, 446 allergic rhinitis-related genes were obtained on the basis of the DisGeNET database. The protein-protein interaction network was searched using the random-walk-with-restart algorithm with these 446 genes as seed nodes to assess the linkages between other genes and allergic rhinitis. Then, this result was further examined by three screening tests, including permutation, interaction, and enrichment tests, which aimed to pick up genes that have strong and special associations with allergic rhinitis. 52 novel genes were finally obtained. The functional enrichment test confirmed their relationships to the biological processes and pathways related to allergic rhinitis. Furthermore, some genes were extensively analyzed to uncover their special or latent associations to allergic rhinitis, including IRAK2 and MAPK, which are involved in the pathogenesis of allergic rhinitis and the inhibition of allergic inflammation via the p38-MAPK pathway, respectively. The new found genes may help the following investigations for understanding the underlying molecular mechanisms of allergic rhinitis and developing effective treatments.

A novel natural Syk inhibitor suppresses IgE-mediated mast cell activation and passive cutaneous anaphylaxis

Spleen tyrosine kinase (Syk) plays a crucial role as a target for allergy treatment due to its involvement in immunoreceptor signaling. The purpose of this study was to identify natural inhibitors of Syk and assess their effects on the IgE-mediated allergic response in mast cells and ICR mice. A list of eight compounds was selected based on pharmacophore and molecular docking, showing potential inhibitory effects through virtual screening. Among these compounds, sophoraflavanone G (SFG) was found to inhibit Syk activity in an enzymatic assay, with an IC50 value of 2.2 μM. To investigate the conformational dynamics of the SYK-SFG system, we performed molecular dynamics simulations. The stability of the binding between SFG and Syk was evaluated using root mean square deviation (RMSD) and root mean square fluctuation (RMSF). In RBL-2H3 cells, SFG demonstrated a dose-dependent suppression of IgE/BSA-induced mast cell degranulation, with no significant cytotoxicity observed at concentrations below 10.0 μM within 24 h. Furthermore, SFG reduced the production of TNF-α and IL-4 in RBL-2H3 cells. Mechanistic investigations revealed that SFG inhibited downstream signaling proteins, including phospholipase Cγ1 (PLCγ1), as well as mitogen-activated protein kinases (AKT, Erk1/2, p38, and JNK), in mast cells in a dose-dependent manner. Passive cutaneous anaphylaxis (PCA) experiments demonstrated that SFG could reduce ear swelling, mast cell degranulation, and the expression of COX-2 and IL-4. Overall, our findings identify naturally occurring SFG as a direct inhibitor of Syk that effectively suppresses mast cell degranulation both in vitro and in vivo.

Advanced and Smart Textiles during and after the COVID-19 Pandemic: Issues, Challenges, and Innovations

The COVID-19 pandemic has hugely affected the textile and apparel industry. Besides the negative impact due to supply chain disruptions, drop in demand, liquidity problems, and overstocking, this pandemic was found to be a window of opportunity since it accelerated the ongoing digitalization trends and the use of functional materials in the textile industry. This review paper covers the development of smart and advanced textiles that emerged as a response to the outbreak of SARS-CoV-2. We extensively cover the advancements in developing smart textiles that enable monitoring and sensing through electrospun nanofibers and nanogenerators. Additionally, we focus on improving medical textiles mainly through enhanced antiviral capabilities, which play a crucial role in pandemic prevention, protection, and control. We summarize the challenges that arise from personal protective equipment (PPE) disposal and finally give an overview of new smart textile-based products that emerged in the markets related to the control and spread reduction of SARS-CoV-2.

The spleen tyrosine kinase (SYK): A crucial therapeutic target for diverse liver diseases

Spleen tyrosine kinase (SYK) is an enigmatic protein tyrosine kinase, and involved in signal transduction related with lots of cellular processes. It's highly expressed in the cells of hematopoietic origin and acts as an important therapeutic target in the treatment of autoimmune diseases and allergic disorders. In recent years, more and more evidences indicate that SYK is expressed in non-hematopoietic cells and effectively regulates various non-immune biological responses as well. In this review, we mainly summary the role of SYK in different liver diseases. Robust SYK expression has been discovered in hepatocytes, hepatic stellate cells, as well as Kupffer cells, which participates in the regulation of numerous signal transduction in various liver diseases (e.g. hepatitis, liver fibrosis and hepatocellular carcinoma). In addition, the blockage of SYK activity using small molecule modulators is considered as a significant therapeutic strategy against liver diseases, and both hepatic SYK and non-hepatic SYK could become highly promising therapeutic targets. Totally, even though some critical points about the significance of SYK in liver diseases treatment still need further elaboration, more reliable biotechnical or pharmacological therapy modes will be established based on the better understanding of the relationship between SYK and liver diseases.

Therapeutic effects of Fc gamma RIV inhibition are mediated by selectively blocking immune complex-induced neutrophil activation in epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita (EBA) is a subepidermal autoimmune bullous disease caused by autoantibodies targeting type VII collagen (COL7). It is characterized by inflammation and subepidermal blistering mainly through immune complex (IC)-mediated activation of neutrophils. In experimental EBA, binding of neutrophils to ICs in the skin and induction of clinical disease depends on the expression of the Fc gamma receptor (FcγR) IV. As activating FcγR mediate both neutrophil extravasation and activation, we used multiphoton imaging to obtain further insights into the mechanistic contribution of FcγRIV in the pathogenesis of EBA. First, we demonstrated that blocking FcγRIV function completely protects LysM-eGFP mice against induction of antibody transfer-induced EBA. To visualize the interactions of anti-COL7 IgG and neutrophils in vivo, fluorescently labeled anti-COL7 IgG was injected into LysM-eGFP mice. Multiphoton microscopy was sequentially performed over a period of 8 days. At all time points, we observed a significantly higher extravasation of neutrophils into the skin of mice treated with anti-FcγRIV antibody compared to controls. However, the percentage of detected neutrophils localized to the target antigen along the dermal-epidermal junction was comparable between both groups. Additionally, reactive oxygen release and migration in vitro assay data demonstrate that FcγRIV antibody treatment inhibits the activation, but not the migration, of neutrophils. Our findings underscore the importance of advanced in vivo imaging techniques to understand the complexity of IC-mediated neutrophil-dependent inflammation, and indicate that the therapeutic utility of FcγRIV blockade is achieved through impairment of IC-mediated neutrophil activation.

Real-World Use of Fostamatinib in Patients with Immune Thrombocytopenia and Thrombotic Risk

Patients with immune thrombocytopenia (ITP) are at increased risk for bleeding and are paradoxically at increased risk for thrombosis. Many patients with ITP have underlying cardiovascular (CV) disease and/or other thrombotic risk factors for which considerable attention to selecting a therapeutic agent to manage ITP is needed. Fostamatinib, a spleen tyrosine kinase inhibitor, may reduce the risk of thrombosis while not interfering with hemostasis. We present a case series of 5 patients with ITP who had significant CV histories; each had at least 2 thrombotic risk factors. After unsuccessful management of ITP with other treatments, fostamatinib was initiated, was observed to be tolerable, and provided a durable platelet response without associated thromboembolic events. Fostamatinib may be the treatment of choice for patients with ITP in whom use of prothrombotic treatments should be avoided and/or continued use of antiplatelet or anticoagulant medication is needed.

Filgotinib or Lanraplenib in Moderate to Severe Cutaneous Lupus Erythematosus: A Phase 2, Randomised, Double-Blind, Placebo-Controlled Study

OBJECTIVES

To explore the safety and efficacy of filgotinib (FIL), a Janus kinase 1 inhibitor, and lanraplenib (LANRA), a spleen kinase inhibitor in cutaneous lupus erythematosus (CLE).

METHODS

This was a phase 2, randomised, double-blind, placebo-controlled, exploratory, proof-of-concept study of LANRA (30 mg), FIL (200 mg), or placebo (PBO) once daily for 12 weeks in patients with active CLE. At week 12, PBO patients were rerandomised 1:1 to receive LANRA or FIL for up to 36 additional weeks.

RESULTS

Of 47 randomised patients, 45 were treated (N = 9 PBO, N = 19 LANRA, N = 17 FIL). The primary end point (change from baseline in Cutaneous Lupus Erythematosus Disease Area and Severity Index Activity [CLASI-A] score at week 12) was not met. Least squares mean (standard error) CLASI-A score change from baseline was -5.5 (2.56) with PBO, -4.5 (1.91) with LANRA, and -8.7 (1.85) with FIL. Numerical differences between FIL and PBO were greater in select subgroups. A ≥ 5-point improvement in CLASI-A score at week 12 was achieved by 50.0%, 56.3%, and 68.8% in the PBO, LANRA, and FIL arms, respectively. A numerically greater proportion of patients in the FIL arm (50%) also achieved ≥50% improvement in CLASI-A score at week 12 (37.5% PBO, 31.3% LANRA). Most adverse events (AEs) were mild or moderate in severity. Two serious AEs were reported with LANRA and 1 with FIL.

CONCLUSION

The primary end point was not met. Select subgroups displayed a numerically greater treatment response to FIL relative to PBO. LANRA and FIL were generally well tolerated.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03134222.

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

Background:

Patients with immune thrombocytopenia (ITP) are at risk of bleeding and, paradoxically, thromboembolic events (TEEs), irrespective of thrombocytopenia. The risk of thrombosis is increased by advanced age, obesity, and prothrombotic comorbidities: cancer, hyperlipidemia, diabetes, hypertension, coronary artery disease, and chronic kidney disease, among others. Certain ITP treatments further increase the risk of TEE, especially splenectomy and thrombopoietin receptor agonists. Spleen tyrosine kinase (SYK) is a key signaling molecule common to thromboembolic and hemostatic (in addition to inflammatory) pathways. Fostamatinib is an orally administered SYK inhibitor approved in the USA and Europe for treatment of chronic ITP in adults.

Methods:

The phase III and extension studies included heavily pretreated patients with long-standing ITP, many of whom had risk factors for thrombosis prior to initiating fostamatinib. This report describes long-term safety and efficacy of fostamatinib in 146 patients with up to 5 years of treatment, a total of 229 patient-years, and assesses the incidence of thromboembolic events (by standardized MedDRA query).

Results:

Platelet counts ⩾50,000/µL were achieved in 54% of patients and the safety profile was as described in the phase III clinical studies with no new toxicities observed over the 5 years of follow-up. The only TEE occurred in one patient (0.7%, or 0.44/100 patient-years), who experienced a mild transient ischemic attack. This is a much lower rate than might be expected in ITP patients.

Conclusion:

This report demonstrates durable efficacy and a very low incidence of TEE in patients receiving long-term treatment of ITP with the SYK inhibitor fostamatinib.

ClinicalTrials.gov identifiers:

NCT02076399, NCT02076412, and NCT02077192.

Characterizing the structure-activity relationships of natural products, tanshinones, reveals their mode of action in inhibiting spleen tyrosine kinase

The cytosolic non-receptor protein kinase, spleen tyrosine kinase (SYK), is an attractive drug target in autoimmune, inflammatory disorder, and cancers indications. Here, we employed pharmacophore-based drug screening combined with biochemical assay and molecular dynamics (MD) simulations to identify and characterize inhibitors targeting SYK. The built pharmacophore model, phar-TanI, successfully identified tanshinone (TanI (IC50 = 1.72 μM)) and its analogs (TanIIA (IC50 = 3.2 μM), ST32da (IC50 = 46 μM), and ST32db (IC50 = 51 μM)) which apparently attenuated the activities of SYK in vitro. Additionally, the MD simulations followed by Ligplot analyses revealed that TanI and TanIIA interfered SYK activity through binding deeply into the active site. Besides, TanI and TanIIA mainly interact with residues L377, A400, V433, M448, M450, A451, E452, L453, G454, P455, and L501, which are functional hotspots for structure-based inhibitor optimization against SYK. The structure-activity relationships (SAR) study of the identified SYK inhibitors demonstrated that the pharmacophore model, phar-TanI is reliable and precise in screening inhibitors against SYK. This study disclosed the structure-function relationships of tanshinones from Traditional Chinese Medicine (Danshen), revealing their binding site and mode of action in inhibiting SYK and provides applicability in developing new therapeutic agents.

Activity Prediction of Small Molecule Inhibitors for Antirheumatoid Arthritis Targets Based on Artificial Intelligence

Rheumatoid arthritis (RA) is a chronic autoimmune disease, which is compared to "immortal cancer" in industry. Currently, SYK, BTK, and JAK are the three major targets of protein tyrosine kinase for this disease. According to existing research, marketed and research drugs for RA are mostly based on single target, which limits their efficacy. Therefore, designing multitarget or dual-target inhibitors provide new insights for the treatment of RA regarding of the specific association between SYK, BTK, and JAK from two signal transduction pathways. In this study, machine learning (XGBoost, SVM) and deep learning (DNN) models were combined for the first time to build a powerful integrated model for SYK, BTK, and JAK. The predictive power of the integrated model was proved to be superior to that of a single classifier. In order to accurately assess the generalization ability of the integrated model, comprehensive similarity analysis was performed on the training and the test set, and the prediction accuracy of the integrated model was specifically analyzed under different similarity thresholds. External validation was conducted using single-target and dual-target inhibitors, respectively. Results showed that our model not only obtained a high recall rate (97%) in single-target prediction, but also achieved a favorable yield (54.4%) in dual-target prediction. Furthermore, by clustering dual-target inhibitors, the prediction performance of model in various classes were proved, evaluating the applicability domain of the model in the dual-target drug screening. In summary, the integrated model proposed is promising to screen dual-target inhibitors of SYK/JAK or BTK/JAK as RA drugs, which is beneficial for the clinical treatment of rheumatoid arthritis.

Progress toward a Glycoprotein VI Modulator for the Treatment of Thrombosis

Pathogenic thrombus formation accounts for the etiology of many serious conditions including myocardial infarction, stroke, deep vein thrombosis, and pulmonary embolism. Despite the development of numerous anticoagulants and antiplatelet agents, the mortality rate associated with these diseases remains high. In recent years, however, significant epidemiological evidence and clinical models have emerged to suggest that modulation of the glycoprotein VI (GPVI) platelet receptor could be harnessed as a novel antiplatelet strategy. As such, many peptidic agents have been described in the past decade, while more recent efforts have focused on the development of small molecule modulators. Herein the rationale for targeting GPVI is summarized and the published GPVI modulators are reviewed, with particular focus on small molecules. A qualitative pharmacophore hypothesis for small molecule ligands at GPVI is also presented.

Role of spleen tyrosine kinase in liver diseases

Spleen tyrosine kinase (SYK) is a non-receptor tyrosine kinase expressed in most hematopoietic cells and non-hematopoietic cells and play a crucial role in both immune and non-immune biological responses. SYK mediate diverse cellular responses via an immune-receptor tyrosine-based activation motifs (ITAMs)-dependent signalling pathways, ITAMs-independent and ITAMs-semi-dependent signalling pathways. In liver, SYK expression has been observed in parenchymal (hepatocytes) and non-parenchymal cells (hepatic stellate cells and Kupffer cells), and found to be positively correlated with the disease severity. The implication of SYK pathway has been reported in different liver diseases including liver fibrosis, viral hepatitis, alcoholic liver disease, non-alcoholic steatohepatitis and hepatocellular carcinoma. Antagonism of SYK pathway using kinase inhibitors have shown to attenuate the progression of liver diseases thereby suggesting SYK as a highly promising therapeutic target. This review summarizes the current understanding of SYK and its therapeutic implication in liver diseases.

Dectin-1/Syk signaling triggers neuroinflammation after ischemic stroke in mice

Background

Dendritic cell-associated C-type lectin-1 (Dectin-1) receptor has been reported to be involved in neuroinflammation in Alzheimer’s disease and traumatic brain injury. The present study was designed to investigate the role of Dectin-1 and its downstream target spleen tyrosine kinase (Syk) in early brain injury after ischemic stroke using a focal cortex ischemic stroke model.

Methods

Adult male C57BL/6 J mice were subjected to a cerebral focal ischemia model of ischemic stroke. The neurological score, adhesive removal test, and foot-fault test were evaluated on days 1, 3, 5, and 7 after ischemic stroke. Dectin-1, Syk, phosphorylated (p)-Syk, tumor necrosis factor-α (TNF-α), and inducible nitric oxide synthase (iNOS) expression was analyzed via western blotting in ischemic brain tissue after ischemic stroke and in BV2 microglial cells subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) injury in vitro. The brain infarct volume and Iba1-positive cells were evaluated using Nissl’s and immunofluorescence staining, respectively. The Dectin-1 antagonist laminarin (LAM) and a selective inhibitor of Syk phosphorylation (piceatannol; PIC) were used for the intervention.

Results

Dectin-1, Syk, and p-Syk expression was significantly enhanced on days 3, 5, and 7 and peaked on day 3 after ischemic stroke. The Dectin-1 antagonist LAM or Syk inhibitor PIC decreased the number of Iba1-positive cells and TNF-α and iNOS expression, decreased the brain infarct volume, and improved neurological functions on day 3 after ischemic stroke. In addition, the in vitro data revealed that Dectin-1, Syk, and p-Syk expression was increased following the 3-h OGD and 0, 3, and 6 h of reperfusion in BV2 microglial cells. LAM and PIC also decreased TNF-α and iNOS expression 3 h after OGD/R induction.

Conclusion

Dectin-1/Syk signaling plays a crucial role in inflammatory activation after ischemic stroke, and further investigation of Dectin-1/Syk signaling in stroke is warranted.

Splenectomy may have more complications than currently proven

The spleen has been one of the least understood major organs for centuries. Its significance is relatively well-known today but it seems that all aspects of its activities are not fully understood. Persian medicine (PM) has special views on the function of spleen; many side effects were reported in PM due to spleen dysfunction. On the other hand nowadays splenectomy as a treatment strategy is recommended for some disorders and increasing risk of infections is considered as the most important long term side effect of that. In this study, we hypothesize that splenectomy may have more side effects than currently proven. According to PM, spleen is in close connection with liver, cardiovascular system, stomach, bone, brain and skin, and that is why any kind of spleen dysfunction leads to change in blood viscosity, appetite and bone strength, liver dysfunction, mood and skin disorders, cancer formation and fever. Considering this viewpoint it can be hypothesized such side effects may also occur after splenectomy. Proven complications of splenectomy include hypercoagulated state, cardiovascular events and infectious diseases but there is also some evidence about increased risk of cancer, skin disease like systemic lupus erythematosus, mood disorder such as depression, defective bone formation and impairment of immunity which can be considered as different levels of evidence to confirm the hypothesis. But for some others such as changes in appetite, there are no studies let alone convincing evidence. Future research about theses possible complications may lead to novel results.

Translational Biomarkers and Ex Vivo Models of Joint Tissues as a Tool for Drug Development in Rheumatoid Arthritis

Objective

Rheumatoid arthritis (RA) is a chronic and degenerative autoimmune joint disease that leads to disability, reduced quality of life, and increased mortality. Although several synthetic and biologic disease‐modifying antirheumatic drugs are available, there is still a medical need for novel drugs that control disease progression. As only 10% of experimental drug candidates for treatment of RA that enter phase I trials are eventually registered by the Food and Drug Administration, there is an immediate need for translational tools to facilitate early decision‐making in drug development. In this study, we aimed to determine if the inability of fostamatinib (a small molecule inhibitor of Syk) to demonstrate sufficient efficacy in phase III of a previous clinical study could have been predicted earlier in the development process.

Methods

Biomarkers of bone, cartilage, and interstitial matrix turnover (C‐telopeptide of type I collagen [CTX‐I], matrix metalloproteinase–derived types I, II, and III collagen neoepitopes [C1M, C2M, and C3M]) were measured in 450 serum samples from the Oral Syk Inhibition in Rheumatoid Arthritis 1 study (OSKIRA‐1, a phase III clinical study of the efficacy of fostamatinib in RA) at baseline and follow‐up. Additionally, the same biomarkers were subsequently measured in conditioned media from osteoclast, cartilage, and synovial membrane cultured with the active metabolite of fostamatinib, R406, to assess the level of suppression induced by the drug.

Results

In OSKIRA‐1 serum samples and osteoclast and cartilage cultures, fostamatinib suppressed the levels of CTX‐I and C2M. In OSKIRA‐1 serum samples and synovial membrane cultures, fostamatinib did not mediate any clinical or preclinical effect on either C1M or C3M, which have previously been associated with disease response and efficacy.

Conclusion

These data demonstrate that translational biomarkers are a potential tool for early assessment and decision‐making in drug development for RA treatment.

Systematic assessment of multi-gene predictors of pan-cancer cell line sensitivity to drugs exploiting gene expression data

Background: Selected gene mutations are routinely used to guide the selection of cancer drugs for a given patient tumour. Large pharmacogenomic data sets, such as those by Genomics of Drug Sensitivity in Cancer (GDSC) consortium, were introduced to discover more of these single-gene markers of drug sensitivity. Very recently, machine learning regression has been used to investigate how well cancer cell line sensitivity to drugs is predicted depending on the type of molecular profile. The latter has revealed that gene expression data is the most predictive profile in the pan-cancer setting. However, no study to date has exploited GDSC data to systematically compare the performance of machine learning models based on multi-gene expression data against that of widely-used single-gene markers based on genomics data. Methods: Here we present this systematic comparison using Random Forest (RF) classifiers exploiting the expression levels of 13,321 genes and an average of 501 tested cell lines per drug. To account for time-dependent batch effects in IC ₅₀ measurements, we employ independent test sets generated with more recent GDSC data than that used to train the predictors and show that this is a more realistic validation than standard k-fold cross-validation. Results and Discussion: Across 127 GDSC drugs, our results show that the single-gene markers unveiled by the MANOVA analysis tend to achieve higher precision than these RF-based multi-gene models, at the cost of generally having a poor recall (i.e. correctly detecting only a small part of the cell lines sensitive to the drug). Regarding overall classification performance, about two thirds of the drugs are better predicted by the multi-gene RF classifiers. Among the drugs with the most predictive of these models, we found pyrimethamine, sunitinib and 17-AAG. Conclusions: Thanks to this unbiased validation, we now know that this type of models can predict in vitro tumour response to some of these drugs. These models can thus be further investigated on in vivo tumour models. R code to facilitate the construction of alternative machine learning models and their validation in the presented benchmark is available at http://ballester.marseille.inserm.fr/gdsc.transcriptomicDatav2.tar.gz.

Systematic assessment of multi-gene predictors of pan-cancer cell line sensitivity to drugs exploiting gene expression data

Background: Selected gene mutations are routinely used to guide the selection of cancer drugs for a given patient tumour. Large pharmacogenomic data sets, such as those by Genomics of Drug Sensitivity in Cancer (GDSC) consortium, were introduced to discover more of these single-gene markers of drug sensitivity. Very recently, machine learning regression has been used to investigate how well cancer cell line sensitivity to drugs is predicted depending on the type of molecular profile. The latter has revealed that gene expression data is the most predictive profile in the pan-cancer setting. However, no study to date has exploited GDSC data to systematically compare the performance of machine learning models based on multi-gene expression data against that of widely-used single-gene markers based on genomics data. Methods: Here we present this systematic comparison using Random Forest (RF) classifiers exploiting the expression levels of 13,321 genes and an average of 501 tested cell lines per drug. To account for time-dependent batch effects in IC ₅₀ measurements, we employ independent test sets generated with more recent GDSC data than that used to train the predictors and show that this is a more realistic validation than standard k-fold cross-validation. Results and Discussion: Across 127 GDSC drugs, our results show that the single-gene markers unveiled by the MANOVA analysis tend to achieve higher precision than these RF-based multi-gene models, at the cost of generally having a poor recall (i.e. correctly detecting only a small part of the cell lines sensitive to the drug). Regarding overall classification performance, about two thirds of the drugs are better predicted by the multi-gene RF classifiers. Among the drugs with the most predictive of these models, we found pyrimethamine, sunitinib and 17-AAG. Conclusions: Thanks to this unbiased validation, we now know that this type of models can predict in vitro tumour response to some of these drugs. These models can thus be further investigated on in vivo tumour models. R code to facilitate the construction of alternative machine learning models and their validation in the presented benchmark is available at http://ballester.marseille.inserm.fr/gdsc.transcriptomicDatav2.tar.gz.

Characterization of the disposition of fostamatinib in Japanese subjects including pharmacokinetic assessment in dry blood spots: results from two phase I clinical studies

PURPOSE

The aims of the present study were to characterize the pharmacokinetics of fostamatinib in two phase I studies in healthy Japanese subjects after single- and multiple-dose administration, and to evaluate the utility of dried blood spot (DBS) sampling.

METHODS

In study A, 40 Japanese and 16 white subjects were randomized in a double-blind parallel group study consisting of seven cohorts, which received either placebo or a fostamatinib dose between 50 and 200 mg after single and multiple dosing. Pharmacokinetics of R406 (active metabolite of fostamatinib) in plasma and urine was assessed, and safety was intensively monitored. Study B was an open-label study that assessed fostamatinib 100 and 200 mg in 24 Japanese subjects. In addition to plasma and urine sampling (as for study A), pharmacokinetics was also assessed in blood.

RESULTS

Mean maximum plasma concentration (C max) and area under total plasma concentration–time curve (AUC) increased with increasing dose in Japanese subjects. Steady state was achieved in 5–7 days for all doses. C max and AUC were both higher in Japanese subjects administered a 150-mg single dose than in white subjects. This difference was maintained for steady state exposure by day 10. Overall, R406 blood concentrations were consistent and ∼2.5-fold higher than in plasma. Minimal (<0.1 %) R406 was excreted in urine. Fostamatinib was well tolerated at all doses.

CONCLUSIONS

Fostamatinib pharmacokinetics following single- and multiple-dose administration was approximately dose proportional at all doses ≤150 mg and greater than dose proportional at 200 mg in Japanese subjects. Japanese subjects administered fostamatinib 150 mg had higher exposure than white subjects. R406 could be measured in DBS samples and distributed into red blood cells, and DBS sampling was a useful method for assessing R406 pharmacokinetics.

PRT062607 Achieves Complete Inhibition of the Spleen Tyrosine Kinase at Tolerated Exposures Following Oral Dosing in Healthy Volunteers

The spleen tyrosine kinase (SYK) regulates immune cell activation in response to engagement of a variety of receptors, making it an intriguing target for the treatment of inflammatory and autoimmune disorders as well as certain B‐cell malignancies. We have previously reported on the discovery and preclinical characterization of PRT062607, a potent and highly selective inhibitor of SYK that exhibits robust anti‐inflammatory activity in a variety of animal models. Here we present data from our first human studies aimed at characterizing the pharmacokinetics (PK), pharmacodynamics (PD), and safety of PRT062607 in healthy volunteers following single and multiple oral administrations. PRT062607 demonstrated a favorable PK profile and the ability to completely inhibit SYK activity in multiple whole‐blood assays. The PD half‐life in the more sensitive assays was approximately 24 hours and returned to predose levels by 72 hours. Selectivity for SYK was observed at all dose levels tested. Analysis of the PK/PD relationship indicated an IC₅₀ of 324 nM for inhibition of B‐cell antigen receptor‐mediated B‐cell activation and 205 nM for inhibition of FcεRI‐mediated basophil degranulation. PRT062607 was safe and well tolerated across the entire range of doses. Clinical PK/PD was related to in vivo anti‐inflammatory activity of PRT062607 in the rat collagen‐induced arthritis model, which predicts that therapeutic concentrations may be safely achieved in humans for the treatment of autoimmune disease. PRT062607 has a desirable PK profile and is capable of safely, potently, and selectively suppressing SYK kinase function in humans following once‐daily oral dosing.

Spleen Tyrosine Kinase: A Crucial Player and Potential Therapeutic Target in Renal Disease

Spleen tyrosine kinase (Syk), a 72 kDa cytoplasmic non-receptor protein-tyrosine kinase, plays an important role in signal transduction in a variety of cell types. Ever since its discovery in the early 1990s, there has been accumulating evidence to suggest a pathogenic role of Syk in various allergic disorders, autoimmune diseases and malignancies. Additionally, there is emerging data from both pre-clinical and clinical studies that Syk is implicated in the pathogenesis of proliferative glomerulonephritis (GN), including anti-glomerular basement membrane disease, anti-neutrophil cytoplasmic antibody-associated GN, lupus nephritis and immunoglobulin A nephropathy (IgAN). Moreover, recent animal studies have shed light on the importance of Syk in mediating acute renal allograft rejection, Epstein Barr virus-associated post-transplant lymphoproliferative disease and kidney fibrosis. Fostamatinib, an oral Syk inhibitor, has undergone clinical testing in rheumatoid arthritis, refractory immune thrombocytopenic purpura, leukemia and lymphoma. The recent STOP-IgAN trial showed that the addition of non-selective immunosuppressive therapy to intensive supportive care did not improve clinical outcomes in high-risk IgAN patients. A Syk-targeted approach may be beneficial and is currently being evaluated in a phase II randomized controlled trial. In this review, we will discuss the pathogenic role of Syk and potential use of Syk inhibitor in a variety of renal diseases.

Syk Inhibition Induces Platelet Dependent Peri-islet Hemorrhage in the Rat Pancreas

Spleen tyrosine kinase (Syk) is a nonreceptor tyrosine kinase that is an important signaling enzyme downstream of immunoreceptors containing an intracellular immunoreceptor tyrosine activating motif (ITAM). These receptors encompass a wide variety of biological functions involved in autoimmune disease pathogenesis. There has been considerable interest in the development of inhibitors of the Syk pathway for the treatment of rheumatoid arthritis and systemic lupus erythematosus. We report that Syk inhibition mechanistically caused peri-islet hemorrhages and fibrin deposition in the rat pancreas and that this finding is due to a homeostatic functional defect in platelets. In more limited studies, similar lesions could not be induced in mice, dogs, and cynomolgus monkeys at similar or higher plasma drug concentrations. Irradiation-induced thrombocytopenia caused a phenotypically similar peri-islet pancreas lesion and the formation of this lesion could be prevented by platelet transfusion. In addition, Syk inhibitor-induced lesions were prevented by the coadministration of prednisone. A relatively greater sensitivity of rat platelets to Syk inhibition was supported by functional analyses demonstrating rat-specific differences in response to convulxin, a glycoprotein VI agonist that signals through Syk. These data demonstrate that the Syk pathway is critical in platelet-endothelial cell homeostasis in the peri-islet pancreatic microvasculature in rats.

The Syk Inhibitor Fostamatinib Decreases the Severity of Colonic Mucosal Damage in a Rodent Model of Colitis

BACKGROUND AND AIMS

Inflammatory bowel disease is a chronic inflammatory disease of the gastrointestinal system. In some cases, current medications used for inflammatory bowel disease may not be enough for remission, creating a need for more potent and reliable medications. There is no study showing the efficacy of fostamatinib, with proven effects on some inflammatory diseases, on ulcerative colitis. In our study we planned to research the efficacy of fostamatinib, a spleen tyrosine kinase inhibitor, on acetic acid-induced colitis.

METHODS

The study included 28 male Sprague-Dawley rats, randomly divided into control group, fostamatinib group, colitis group and fostamatinib + colitis group, each containing seven rats. Colitis induction was performed with 4% acetic acid. Colonic inflammation was assessed with disease activity index, macroscopic and histological damage scores, colonic myeloperoxidase, malondialdehyde and superoxide dismutase activity, and tumour necrosis factor alpha [TNFα], CD3, Syk, and phospho-Syk expression.

RESULTS

There was a significant difference between the colitis and control groups in terms of all parameters. The disease activity index, macroscopic and microscopic damage scores, immunohistochemical TNFα, CD3, Syk, and phospho-Syk expression, and tissue myeloperoxidase activity were found to be significantly lower in the colitis + fostamatinib group compared with the colitis group. There was no significant difference between the two groups in terms of myeloperoxidase and malondialdehyde activity.

CONCLUSIONS

Fostamatinib reduced the inflammatory damage in the experimental colitis. This effect may be due to suppression of TNFα, T-lymphocytes, and neutrophils in colonic mucosa via suppression of Syk. Fostamatinib may be an appropriate treatment alternative for ulcerative colitis. Further clinical studies are required to support this.

VHR/DUSP3 phosphatase: structure, function and regulation

Vaccinia H1-related (VHR) phosphatase, also known as dual-specificity phosphatase (DUSP) 3, is a small member of the DUSP (also called DSP) family of phosphatases. VHR has a preference for phospho-tyrosine substrates, and has important roles in cellular signaling ranging from cell-cycle regulation and the DNA damage response to MAPK signaling, platelet activation and angiogenesis. VHR/DUSP3 has been implicated in several human cancers, where its tumor-suppressing and -promoting properties have been described. We give a detailed overview of VHR/DUSP3 phosphatase and compare it with its most closely related phosphatases DUSP13B, DUSP26 and DUSP27.

OSKIRA-4: a phase IIb randomised, placebo-controlled study of the efficacy and safety of fostamatinib monotherapy

Objectives

OSKIRA-4 evaluated the efficacy of fostamatinib monotherapy versus placebo on the signs and symptoms of rheumatoid arthritis over 6 weeks by Disease Activity Score C reactive protein (DAS-28(CRP)) and assessed non-inferiority to adalimumab monotherapy at Week 24 by DAS-28(CRP).

Methods

Overall, 279 patients not currently taking disease-modifying antirheumatic drugs were randomised to: (A) fostamatinib 100 mg twice daily for 24 weeks plus placebo injection every 2 weeks (PBOI); (B) fostamatinib 100 mg twice daily for 4 weeks, then 150 mg once daily up to Week 24, plus PBOI; (C) fostamatinib 100 mg twice daily for 4 weeks, then 100 mg once daily up to Week 24, plus PBOI; (D) adalimumab 40 mg every 2 weeks for 24 weeks, plus oral placebo twice daily; or (E) oral placebo twice daily for 6 weeks, plus PBOI, then a switch to arm A or B.

Results

Fostamatinib demonstrated a significant improvement in DAS-28(CRP) score from baseline versus placebo at Week 6 for arms A and B, but not C. Fostamatinib was significantly less effective than adalimumab at Week 24 based on DAS-28(CRP). Adverse events observed with fostamatinib treatment were consistent with those reported in previous studies, including hypertension and diarrhoea.

Conclusions

Fostamatinib demonstrated efficacy as monotherapy, showing superior DAS-28(CRP) score changes between baseline and 6 weeks when compared with placebo in treatment arms A and B. However, all fostamatinib regimens demonstrated inferior responses compared with adalimumab at Week 24.

Trial registration number

Clinicaltrials.gov: NCT01264770.

Molecular abnormalities of the B cell in systemic lupus erythematosus are candidates for functional inhibition treatments

INTRODUCTION

The B cell is a key player in the pathogenesis of systemic lupus erythematosus (SLE). Loss of B cell tolerance resulting in autoantibody production and immune complex formation and deposition are central features of the disease. B cell overactivity is a hallmark of SLE and molecular abnormalities in B cell signaling cascade have been described.

AREAS COVERED

In this review, we will focus on the aberrant phenotype of B cell signaling in patients with lupus. We will also discuss data stemming from the use of small molecules that have recently been recognized to target important steps of the B cell signal transduction pathways with therapeutic implications for SLE.

EXPERT OPINION

Attempts to target the B cell in SLE have been made through depletion, blocking of survival factors and co-receptor inhibition. However, the still unmet need for effective therapy of refractory disease makes the necessity for new drugs impelling.

Inhibition of spleen tyrosine kinase as treatment of postoperative ileus

OBJECTIVE

Intestinal inflammation resulting from manipulation-induced mast cell activation is a crucial mechanism in the pathophysiology of postoperative ileus (POI). Recently it has been shown that spleen tyrosine kinase (Syk) is involved in mast cell degranulation. Therefore, we have evaluated the effect of the Syk-inhibitor GSK compound 143 (GSK143) as potential treatment to shorten POI.

DESIGN

In vivo: in a mouse model of POI, the effect of the Syk inhibitor (GSK143) was evaluated on gastrointestinal transit, muscular inflammation and cytokine production. In vitro: the effect of GSK143 and doxantrazole were evaluated on cultured peritoneal mast cells (PMCs) and bone marrow derived macrophages.

RESULTS

In vivo: intestinal manipulation resulted in a delay in gastrointestinal transit at t=24 h (Geometric Center (GC): 4.4 ± 0.3). Doxantrazole and GSK143 significantly increased gastrointestinal transit (GC doxantrazole (10 mg/kg): 7.2 ± 0.7; GSK143 (1 mg/kg): 7.6 ± 0.6), reduced inflammation and prevented recruitment of immune cells in the intestinal muscularis. In vitro: in PMCs, substance P (0-90 μM) and trinitrophenyl (0-4 μg/ml) induced a concentration-dependent release of β-hexosaminidase. Pretreatment with doxantrazole and GSK143 (0.03-10 μM) concentration dependently blocked substance P and trinitrophenyl induced β-hexosaminidase release. In addition, GSK143 was able to reduce cytokine expression in endotoxin-treated bone marrow derived macrophages in a concentration-dependent manner.

CONCLUSIONS

The Syk inhibitor GSK143 reduces macrophage activation and mast cell degranulation in vitro. In addition, it inhibits manipulation-induced intestinal muscular inflammation and restores intestinal transit in mice. These findings suggest that Syk inhibition may be a new tool to shorten POI.

Small molecules in the treatment of systemic lupus erythematosus

Advances in the understanding of the cellular biological events that underlie systemic lupus erythematosus (SLE) have led to the identification of key molecules and signaling pathways that are aberrantly expressed. The parallel development of small molecule drugs that inhibit or interfere with the specific perturbations identified, offers perspective for more rational, effective and less toxic therapy. In this review, we present data from preclinical and clinical studies of such emerging novel therapies with a particular focus on kinase inhibitors and other compounds that modulate signal transduction. Moreover, we highlight the use of chromatin-modifying medications, bringing attention to the central role of epigenetics in SLE pathogenesis.

Inhibitors of switch kinase 'spleen tyrosine kinase' in inflammation and immune-mediated disorders: a review

Spleen tyrosine kinase (Syk), a member of Syk family of non-receptor protein tyrosine kinases plays a significant role in the immune cell signaling in B cells, mast cells, macrophages and neutrophils. Anomalous regulation of this kinase can lead to different allergic disorders and antibody-mediated autoimmune diseases such as rheumatoid arthritis, asthma, psoriasis and allergic rhinitis. Being involved in the growth and survive mechanism of B cells, its inhibition can be beneficial in B-cell lymphoma. Thus, Syk can be sited as a therapeutically relevant target for various allergic and autoimmune disorders. This review article describes the structure of Syk and its role in B-cell signaling. In addition to this, data regarding small molecule inhibitors of Syk has also been reviewed from different papers and patents published.

Development of a pharmacodynamic assay based on PLCγ2 phosphorylation for quantifying spleen tyrosine kinase (SYK)-Bruton's tyrosine kinase (BTK) signaling

Spleen tyrosine kinase (SYK) and Bruton's tyrosine kinase (BTK) are key mediators in coupling cell surface receptors, such as the B-cell receptor (BCR), to downstream signaling events affecting diverse biological functions. There is therefore tremendous interest in the development of pharmacological inhibitors targeting the SYK-BTK axis for the treatment of inflammatory disorders and hematological malignancies. A good pharmacodynamic (PD) assay, ideally a blood-based assay that measures proximal events, is warranted for evaluation of such inhibitors. In platelets, collagen-induced activation of membrane glycoprotein GPVI is dependent on the SYK-BTK axis. Here, we report the development of a novel immunoassay that uses the dissociation-enhanced lanthanide fluorescent immunoassay (DELFIA) to measure GPVI-mediated phosphorylation of phospholipase C γ2 (PLCγ2), a direct substrate of SYK and BTK, in platelets. The assay was validated using SYK or BTK inhibitors and generated IC50 correlated with those from the BCR-induced B-cell activation assay. Furthermore, this assay showed good stability and uniformity over a period of 24 h in different donors. Interestingly, compound IC50 values using blood from patients with rheumatoid arthritis were slightly higher compared with those produced using samples from healthy donors. This novel platelet PLCγ2 phosphorylation-based immunoassay should serve as a promising PD assay for preclinical and clinical development of inhibitors targeting the SYK-BTK axis.

Cellular targeting in autoimmunity

Many biologic agents that were first approved for the treatment of malignancies are now being actively investigated and used in a variety of autoimmune diseases such as rheumatoid arthritis (RA), antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, systemic lupus erythematosus (SLE), and Sjogren's syndrome. The relatively recent advance of selective immune targeting has significantly changed the management of autoimmune disorders and in part can be attributed to the progress made in understanding effector cell function and their signaling pathways. In this review, we will discuss the recent FDA-approved biologic therapies that directly target immune cells as well as the most promising investigational drugs affecting immune cell function and signaling for the treatment of autoimmune disease.

Targeting the SYK-BTK axis for the treatment of immunological and hematological disorders: recent progress and therapeutic perspectives

Spleen Tyrosine Kinase (SYK) and Bruton's Tyrosine Kinase (BTK) are non-receptor cytoplasmic tyrosine kinases that are primarily expressed in cells of hematopoietic lineage. Both are key mediators in coupling activated immunoreceptors to downstream signaling events that affect diverse biological functions, from cellular proliferation, differentiation and adhesion to innate and adaptive immune responses. As such, pharmacological inhibitors of SYK or BTK are being actively pursued as potential immunomodulatory agents for the treatment of autoimmune and inflammatory disorders. Deregulation of SYK or BTK activity has also been implicated in certain hematological malignancies. To date, from a clinical perspective, pharmacological inhibition of SYK activity has demonstrated encouraging efficacy in patients with rheumatoid arthritis (RA), while patients with relapsed or refractory chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) have benefited from covalent inhibitors of BTK in early clinical studies. Here, we review and discuss recent insights into the emerging role of the SYK-BTK axis in innate immune cell function as well as in the maintenance of survival and homing signals for tumor cell progression. The current progress on the clinical development of SYK and BTK inhibitors is also highlighted.

Exploring the role of water molecules for docking and receptor guided 3D-QSAR analysis of naphthyridine derivatives as spleen tyrosine kinase (Syk) inhibitors

In the present study, 3D-QSAR analysis was performed utilizing docking based alignment of [1,6]-naphthyridine derivatives as Syk enzyme inhibitors. The role of the water molecules was explored for the docking based alignment that revealed two conserved water molecules important for proper orientation and alignment of naphthyridine inhibitors in the active site of Syk enzyme. The QSAR model was selected having highest value of Q(2) (0.624) and Pearson-r (0.862). The selected model also displayed the highest values of R(2) (0.978) and F-value (184.5) and the lowest SD (0.862). The contour plots developed on the basis of the best model helped to reveal the essential structural features of naphthyridines derivatives responsible for inhibition of Syk enzyme. The generated model and information revealed from it was utilized to design and predict new congeneric molecules that can be used as potential therapeutic agents.

Quinoxaline derivatives: a patent review (2006--present)

INTRODUCTION

Quinoxaline scaffold is included in a large number of therapeutic agents because of its physicochemical properties that make the difference between them and the carbono analogue, naphthalene.

AREAS COVERED

This review of patented products presents the quinoxaline heterocycle as part of the structural patent claims from a medicinal chemistry perspective.

EXPERT OPINION

We centred our discussion in the various drug patent applications of the quinoxaline and its derivatives. The applications are based firstly in the specific enzyme target with very low development in the disease treatment. Only for cancer and antimicrobial agents they were specifically determined but little is mentioned in order to insight in the last development activities.

Inflammation and vascular injury: basic discovery to drug development

The invited special lecture at the 76(th) Annual Scientific Meeting of the Japanese Circulation Society focused on the central role of inflammation in vascular injury and repair. Early studies pioneered the concept that mechanical injury, such as balloon angioplasty and endovascular stent deployment, elicits an inflammatory response from the vessel wall. This hypothesis was developed and substantiated at a time when the prevailing dogma viewed restenosis following angioplasty as a primarily proliferative smooth muscle cell disease. Antibody targeting of Mac-1 reduced leukocyte accumulation and limited neointimal formation following balloon injury or stent implantation. Genetic absence of Mac-1 resulted in diminished leukocyte accumulation and neointimal thickening after carotid artery injury in mice. In the course of those studies, our laboratory made fundamental discoveries regarding the mechanism of leukocyte recruitment at sites of vascular injury and identified platelet glycoprotein (GP) Ibα, a component of the GPIb-IX-V complex, as the previously unknown platelet counter-receptor for Mac-1. Follow-on studies have focused extensively on the structure, function, and signaling of the leukocyte integrin Mac-1. The binding site for GPIbα in Mac-1 has been mapped and subsequently showed that leukocyte engagement of platelet GPIbα via Mac-1 is critical not only for the biological response to vascular injury, but also for thrombosis, vasculitis, glomerulonephritis, and multiple sclerosis, thereby advancing the hypothesis that virtually all inflammation is platelet-dependent. Furthermore, ligand engagement of Mac-1 initiates a novel gene program that promotes inflammation by activating NFκB and downregulating the expression of the forkhead transcription factor Foxp1 that controls monocyte differentiation. Small molecule inhibitors of Mac-1 function have been pursued, including targeting of Mac-1-GPIbα binding or the downstream tyrosine kinase spleen tyrosine kinase. Drs Teruo Inoue, Koichi Node, Tatsuya Fukotomi, Masashi Sakuma, Toshifumi Morooka, and Kohsuke Nakajima, valued Japanese collaborators and post-doctoral fellows, have contributed enormously to these discoveries.

Pathogenesis of epidermolysis bullosa acquisita, an autoimmune subepidermal bullous disease

Autoimmune bullous diseases (ABDs) are organ-specific autoimmune diseases, in which blisters on the skin and mucous membranes develop through binding of pathogenic autoantibodies to target antigens. There are two major ABD groups: the pemphigus group, showing autoantibodies to desmosomal components; and the subepidermal ABD group, showing autoantibodies to hemidesmosomal components in the epidermal basement membrane zone. Recent immunological, biochemical and molecular biological studies revealed many new autoantigens, including desmocollins, various plakin family proteins and integrins. A revised ABD classification includes new disease entities such as paraneoplastic pemphigus, IgA pemphigus and anti-laminin γ1 pemphigoid. In addition to systemic corticosteroids and various immunosuppressive agents, various adjuvant therapies for ABDs have developed. Among them, intravenous immunoglobulin (IVIG) is a promising therapy, although the therapeutic mechanisms are still unknown. Various disease models for ABDs have developed, particularly for pemphigus vulgaris, bullous pemphigoid and epidermolysis bullosa acquisita (EBA), and these have provided insights into the pathogenesis of various ADBs that suggest possible new treatment strategies. However, the fundamental mechanisms in disruption of immune-tolerance are still unknown. EBA shows autoimmunity to type VII collagen, the major component of anchoring fibrils, and EBA pathogenesis has been studied in various disease models. Previous studies suggested that, following binding of autoantibodies to type VII collagen, activation of complement, cytokine release, neutrophil migration, Fcγ receptors (FcgRs) and metalloproteinases play important roles in induction of subepidermal blisters. In this issue of the Journal of Pathology, Kasperkiewicz and colleagues reveal important roles of activating FcgRIV and inhibitory FcgRIIB in EBA pathogenesis that were recognized by conducting elegant studies using both genetic analysis and functional animal model methods. The expression equilibrium of the activating and inhibitory FcgRs can be modulated towards the inhibitory FcgRIIB by IVIG therapy, resulting in beneficial clinical effects of IVIG in EBA and other autoimmune skin-blistering diseases.

Inhibition of Syk activity by R788 in platelets prevents remote lung tissue damage after mesenteric ischemia-reperfusion injury

Tissue injury following ischemia-reperfusion (I/R) occurs as a consequence of actions of soluble factors and immune cells. Growing evidence supports a role for platelets in the manifestation of tissue damage following I/R. Spleen tyrosine kinase has been well documented to be important in lymphocyte activation and more recently in platelet activation. We performed experiments to evaluate whether inhibition of platelet activation through inhibition of spleen tyrosine kinase prevents tissue damage after mesenteric I/R injury. Platelets isolated from C57BL/6J mice fed with R788 for 10 days were transfused into C57BL/6J mice depleted of platelets 2 days before mesenteric I/R injury. Platelet-depleted mice transfused with platelets from R788-treated mice before mesenteric I/R displayed a significant reduction in the degree of remote lung damage, but with little change in the degree of local intestinal damage compared with control I/R mice. Transfusion of R788-treated platelets also decreased platelet sequestration, C3 deposition, and immunoglobulin deposition in lung, but not in the intestine, compared with control groups. These findings demonstrate that platelet activation is a requisite for sequestration in the pulmonary vasculature to mediate remote tissue injury after mesenteric I/R. The use of small-molecule inhibitors may be valuable to prevent tissue damage in remote organs following I/R injury.