Anti-leukaemic activity of the TYK2 selective inhibitor NDI-031301 in T-cell acute lymphoblastic leukaemia

Novel Biomarkers and Molecular Targets in ALL

PURPOSE OF REVIEW

Acute lymphoblastic leukemia (ALL) is a widely heterogeneous disease in terms of genomic alterations, treatment options, and prognosis. While ALL is considered largely curable in children, adults tend to have higher risk disease subtypes and do not respond as favorably to conventional chemotherapy. Identifying genomic drivers of leukemogenesis and applying targeted therapies in an effort to improve disease outcomes is an exciting focus of current ALL research. Here, we review recent updates in ALL targeted therapy and present promising opportunities for future research.

RECENT FINDINGS

With the utilization of next-generation sequencing techniques, the genomic landscape of ALL has greatly expanded to encompass novel subtypes characterized by recurrent chromosomal rearrangements, gene fusions, sequence mutations, and distinct gene expression profiles. The evolution of small molecule inhibitors and immunotherapies, and the exploration of unique therapy combinations are some examples of recent advancements in the field. Targeted therapies are becoming increasingly important in the treatment landscape of ALL to improve outcomes and minimize toxicity. Significant recent advancements have been made in the detection of susceptible genomic drivers and the use of novel therapies to target them.

Unraveling the complexity of STAT3 in cancer: molecular understanding and drug discovery

Signal transducer and activator of transcription 3 (STAT3) is a transcriptional factor involved in almost all cancer hallmark features including tumor proliferation, metastasis, angiogenesis, immunosuppression, tumor inflammation, metabolism reprogramming, drug resistance, cancer stemness. Therefore, STAT3 has become a promising therapeutic target in a wide range of cancers. This review focuses on the up-to-date knowledge of STAT3 signaling in cancer. We summarize both the positive and negative modulators of STAT3 together with the cancer hallmarks involving activities regulated by STAT3 and highlight its extremely sophisticated regulation on immunosuppression in tumor microenvironment and metabolic reprogramming. Direct and indirect inhibitors of STAT3 in preclinical and clinical studies also have been summarized and discussed. Additionally, we highlight and propose new strategies of targeting STAT3 and STAT3-based combinations with established chemotherapy, targeted therapy, immunotherapy and combination therapy. These efforts may provide new perspectives for STAT3-based target therapy in cancer.

Potential applications of JAK inhibitors, clinically approved drugs against autoimmune diseases, in cancer therapy

Disturbances in immunoregulation may lead to both cancer and autoimmune diseases. Many therapeutic drugs for autoimmune diseases also display anti-tumor efficacy. The Janus kinase/signal transducer and activator of transcription signaling pathways are involved in the secretion of more than 50 distinct cytokines, which have critical roles in inducing autoimmune diseases and tumorigenesis. Thus, Janus kinases have become classical immunotherapeutic targets for immune disease. More than 70 Janus kinase inhibitors have been approved as immunomodulatory drugs for clinical use, of which 12 are used in the treatment of autoimmune diseases. This systematic review aims to elucidate the anti-tumor role of clinically approved Janus kinase inhibitors that were primarily designed for the treatment of autoimmune diseases and their potential for clinical translation as cancer treatments.

Targeting TYK2 for Fighting Diseases: Recent Advance of TYK2 Inhibitors

TYK2 (tyrosine-protein kinase 2) is a non-receptor protein kinase belonging to the JAK family and is closely associated with various diseases, such as psoriasis, inflammatory bowel disease, systemic lupus erythematosus. TYK2 activates the downstream proteins STAT1-5 by participating in the signal transduction of immune factors such as IL-12, IL-23, and IL-10, resulting in immune expression. The activity of the inhibitor TYK2 can effectively block the transduction of excessive immune signals and treat diseases. TYK2 inhibitors are divided into two types of inhibitors according to the different binding sites. One is a TYK2 inhibitor that binds to JH2 and inhibits its activity through an allosteric mechanism. The representative inhibitor is BMS-986165, developed by Bristol-Myers Squibb. The other class binds to the JH1 adenosine triphosphate (ATP) site and prevents the catalytic activity of the kinase by blocking ATP and downstream phosphorylation. This paper mainly introduces the protein structure, signaling pathway, synthesis, structure-activity relationship and clinical research of TYK2 inhibitors.

Identification and Biological Evaluation of a Potent and Selective JAK1 Inhibitor for the Treatment of Pulmonary Fibrosis

Janus kinase 1 (JAK1) plays a pivotal role in regulating inflammation and fibrosis via the JAK/STAT signaling pathway, making it a promising target for associated diseases. In this study, we explored the modification of an N-methyl 1H-pyrrolo[2,3-b]pyridine-5-carboxylate core, leading to the identification of 4-(((2S,4S)-1-(4-trifluoromethyl)-2-methylpiperidin-4-yl)amino)-N-methyl-1H-pyrrolo[2,3-b]pyridine-5-carboxamide (36b) as a highly potent and selective JAK1 inhibitor. Compound 36b exhibited an impressive IC50 value of 0.044 nM for JAK1 and demonstrated remarkable selectivity of 382-fold, 210-fold, and 1325-fold specificity over JAK2, JAK3, and TYK2, respectively. The kinase panel assays further confirmed its specificity, and cell-based experiments established its efficacy in inhibiting JAK1-STAT phosphorylation in human L-132 or SK-MES-1 cells. Pharmacokinetic studies revealed that compound 36b boasts an oral bioavailability exceeding 36%. In a bleomycin-induced fibrosis mouse model, compound 36b significantly reduced STAT3 phosphorylation, resulting in improvement in body weight and reduced collagen deposition, all achieved without significant side effects.

MEK Inhibition Synergizes with TYK2 Inhibitors in NF1-Associated Malignant Peripheral Nerve Sheath Tumors

PURPOSE

Malignant peripheral nerve sheath tumors (MPNST) are aggressive sarcomas with limited treatment options and poor survival rates. About half of MPNST cases are associated with the neurofibromatosis type 1 (NF1) cancer predisposition syndrome. Overexpression of TYK2 occurs in the majority of MPNST, implicating TYK2 as a therapeutic target.

EXPERIMENTAL DESIGN

The effects of pharmacologic TYK2 inhibition on MPNST cell proliferation and survival were examined using IncuCyte live cell assays in vitro, and downstream actions were analyzed using RNA-sequencing (RNA-seq), qPCR arrays, and validation of protein changes with the WES automated Western system. Inhibition of TYK2 alone and in combination with MEK inhibition was evaluated in vivo using both murine and human MPNST cell lines, as well as MPNST PDX.

RESULTS

Pharmacologic inhibition of TYK2 dose-dependently decreased proliferation and induced apoptosis over time. RNA-seq pathway analysis on TYK2 inhibitor-treated MPNST demonstrated decreased expression of cell cycle, mitotic, and glycolysis pathways. TYK2 inhibition resulted in upregulation of the MEK/ERK pathway gene expression, by both RNA-seq and qPCR array, as well as increased pERK1/2 levels by the WES Western system. The compensatory response was tested with dual treatment with TYK2 and MEK inhibitors, which synergistically decreased proliferation and increased apoptosis in vitro. Finally, combination therapy was shown to inhibit growth of MPNST in multiple in vivo models.

CONCLUSIONS

These data provide the preclinical rationale for the development of a phase I clinical trial of deucravacitinib and mirdametinib in NF1-assosciated MPNST.

TYK2 correlates with immune infiltration: A prognostic marker for head and neck squamous cell carcinoma

Tyrosine kinase 2 (TYK2) is a member of the Janus kinase (JAK) family and is involved in immune and inflammatory signaling. TYK2 is overexpressed in several types of cancers and promotes the invasion and proliferation of cancer cells. Nevertheless, the roles of TYK2 in the prognosis and immune infiltration of head and neck squamous cell carcinoma (HNSCC) remain to be elucidated. In this study, the expression of TYK2 in HNSCC was evaluated based on the data retrieved from multiple databases and quantitative real-time polymerase chain reaction (qRT-PCR) analysis. The prognostic potential of TYK2 in patients with HNSCC was analyzed by Kaplan-Meier curves and Cox regression analysis. A TYK2-related risk assessment model was subsequently constructed by Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis and stepwise multivariate Cox regression analysis. The association between the expression of TYK2 and the tumor immune microenvironment, immune checkpoints, and drug sensitivity was explored various packages in R. Cell function assays were finally used for exploring the effects of TYK2 on the growth and metastasis of HNSCC tumors. The expression of TYK2 was significantly upregulated in HNSCC and was found to be closely correlated with HPV status, gender, clinical grade, and TP53 mutation status. Survival analysis suggested that TYK2 is associated with better survival outcomes and acts as an independent prognostic indicator of HNSCC. The model constructed herein also performed well in terms of predicting patient prognosis. The expression of TYK2 was positively associated with the population of tumor-infiltrating immune cells, expression of immune checkpoint genes, and antitumor drug susceptibility. Functionally, TYK2 knockdown significantly promoted the proliferation, migration, and invasion of HNSCC cell lines in vitro. The findings demonstrated that TYK2 could serve as a suppressor of tumor growth and holds significant promise as a novel biomarker for assessing the prognosis of patients with HNSCC and aid in immunotherapy against HNSCC.

Novel TYK2 Inhibitors with an N-(Methyl-d 3)pyridazine-3-carboxamide Skeleton for the Treatment of Autoimmune Diseases

Tyrosine kinase 2 (TYK2) mediates the interleukin-23 (IL-23), IL-12, and type I interferon (IFN)-driven signal responses that are critical in autoimmune diseases. Here, a series of novel derivatives with an N-(methyl-d 3)pyridazine-3-carboxamide skeleton that bind to the TYK2 pseudokinase domain were designed, synthesized, and evaluated. Among them, compound 30 demonstrated more excellent inhibitory potency against STAT3 phosphorylation than the positive control deucravacitinib. In addition to JAK isoform selectivity, compound 30 exhibited good in vivo and in vitro pharmacokinetic properties. Furthermore, compound 30 was orally highly effective in both IL-23-driven acanthosis and anti-CD40-induced colitis models. Together, these findings support compound 30 as a promising candidate for therapeutic applications in autoimmune diseases.

Phosphoproteomic profiling of T cell acute lymphoblastic leukemia reveals targetable kinases and combination treatment strategies

Protein kinase inhibitors are amongst the most successful cancer treatments, but targetable kinases activated by genomic abnormalities are rare in T cell acute lymphoblastic leukemia. Nevertheless, kinases can be activated in the absence of genetic defects. Thus, phosphoproteomics can provide information on pathway activation and signaling networks that offer opportunities for targeted therapy. Here, we describe a mass spectrometry-based global phosphoproteomic profiling of 11 T cell acute lymphoblastic leukemia cell lines to identify targetable kinases. We report a comprehensive dataset consisting of 21,000 phosphosites on 4,896 phosphoproteins, including 217 kinases. We identify active Src-family kinases signaling as well as active cyclin-dependent kinases. We validate putative targets for therapy ex vivo and identify potential combination treatments, such as the inhibition of the INSR/IGF-1R axis to increase the sensitivity to dasatinib treatment. Ex vivo validation of selected drug combinations using patient-derived xenografts provides a proof-of-concept for phosphoproteomics-guided design of personalized treatments.

TYK2 in Cancer Metastases: Genomic and Proteomic Discovery

Advances in genomic analysis and proteomic tools have rapidly expanded identification of biomarkers and molecular targets important to cancer development and metastasis. On an individual basis, personalized medicine approaches allow better characterization of tumors and patient prognosis, leading to more targeted treatments by detection of specific gene mutations, overexpression, or activity. Genomic and proteomic screens by our lab and others have revealed tyrosine kinase 2 (TYK2) as an oncogene promoting progression and metastases of many types of carcinomas, sarcomas, and hematologic cancers. TYK2 is a Janus kinase (JAK) that acts as an intermediary between cytokine receptors and STAT transcription factors. TYK2 signals to stimulate proliferation and metastasis while inhibiting apoptosis of cancer cells. This review focuses on the growing evidence from genomic and proteomic screens, as well as molecular studies that link TYK2 to cancer prevalence, prognosis, and metastasis. In addition, pharmacological inhibition of TYK2 is currently used clinically for autoimmune diseases, and now provides promising treatment modalities as effective therapeutic agents against multiple types of cancer.

LINC00665 promotes the viability, migration and invasion of T cell acute lymphoblastic leukemia cells by targeting miR-101 via modulating PI3K/Akt pathway

T cell acute lymphoblastic leukemia (T-ALL) is a high-risk malignancy. The effects of cancer growth-related Long Intergenic Non-Protein Coding RNA 665 (LINC00665) in T-ALL remained obscure, and therefore further exploration was conducted on that in this study. The expression of LINC00665 in acute myeloid leukemia (LAML) tissues and myeloid tissues was analyzed using Gene Expression Profiling Interactive Analysis (GEPIA) 2. The target microRNA (miR) of LINC00665 was predicted by LncBase Predicted v.2 and verified using dual-luciferase reporter assay. After LINC00665 and miR-101 in T-ALL cells were overexpressed or silenced, the viability, migration and invasion of cell were detected using cell counting kit-8 and Transwell assays. The expressions of LINC00665, miR-101, Cyclin D1, Matrix metalloproteinases (MMP)-2, MMP-9, phosphorylated (p)-phosphatidylinositol 3-kinase (PI3K), PI3K, p-Akt, Akt were detected by quantitative real-time Polymerase Chain Reaction (qRT-PCR) and western blot. High expression of LINC00665 was presented in LAML tissues, the peripheral blood samples from patients with T-ALL and T-ALL cells. Overexpression of LINC00665 promoted the viability, migration and invasion of T-ALL cells and downregulated miR-101 expression, whereas silencing of LINC00665 did oppositely. MiR-101 could competitively bind to LINC00665, and was low-expressed in T-ALL. MiR-101 mimic inhibited viability, migration and invasion of T-ALL cells, and reversed effects of overexpressed LINC00665, whilst miR-101 inhibitor reversed the effects of LINC00665 silencing. Besides, overexpressed LINC00665 upregulated the expressions of Cyclin D1 MMP-2, and MMP-9 and the ratios of p-PI3K/PI3K and p-Akt/Akt, which were reversed by miR-101 mimic. LINC00665 could enhance the viability, migration and invasion abilities of T-ALL cells by targeting miR-101 via activating PI3K/Akt pathway.

Janus Kinases in Leukemia

Janus kinases (JAKs) transduce signals from dozens of extracellular cytokines and function as critical regulators of cell growth, differentiation, gene expression, and immune responses. Deregulation of JAK/STAT signaling is a central component in several human diseases including various types of leukemia and other malignancies and autoimmune diseases. Different types of leukemia harbor genomic aberrations in all four JAKs (JAK1, JAK2, JAK3, and TYK2), most of which are activating somatic mutations and less frequently translocations resulting in constitutively active JAK fusion proteins. JAKs have become important therapeutic targets and currently, six JAK inhibitors have been approved by the FDA for the treatment of both autoimmune diseases and hematological malignancies. However, the efficacy of the current drugs is not optimal and the full potential of JAK modulators in leukemia is yet to be harnessed. This review discusses the deregulation of JAK-STAT signaling that underlie the pathogenesis of leukemia, i.e., mutations and other mechanisms causing hyperactive cytokine signaling, as well as JAK inhibitors used in clinic and under clinical development.

How Well Does the Extended Linear Interaction Energy Method Perform in Accurate Binding Free Energy Calculations?

With continually increased computer power, molecular mechanics force field-based approaches, such as the endpoint methods of molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) and molecular mechanics generalized Born surface area (MM-GBSA), have been routinely applied in both drug lead identification and optimization. However, the MM-PB/GBSA method is not as accurate as the pathway-based alchemical free energy methods, such as thermodynamic integration (TI) or free energy perturbation (FEP). Although the pathway-based methods are more rigorous in theory, they suffer from slow convergence and computational cost. Moreover, choosing adequate perturbation routes is also crucial for the pathway-based methods. Recently, we proposed a new method, coined extended linear interaction energy (ELIE) method, to overcome some disadvantages of the MM-PB/GBSA method to improve the accuracy of binding free energy calculation. In this work, we have systematically assessed this approach using in total 229 protein-ligand complexes for eight protein targets. Our results showed that ELIE performed much better than the molecular docking and MM-PBSA method in terms of root-mean-square error (RMSE), correlation coefficient (R), predictive index (PI), and Kendall's τ. The mean values of PI, R, and τ are 0.62, 0.58, and 0.44 for ELIE calculations. We also explored the impact of the length of simulation, ranging from 1 to 100 ns, on the performance of binding free energy calculation. In general, extending simulation length up to 25 ns could significantly improve the performance of ELIE, while longer molecular dynamics (MD) simulation does not always perform better than short MD simulation. Considering both the computational efficiency and achieved accuracy, ELIE is adequate in filling the gap between the efficient docking methods and computationally demanding alchemical free energy methods. Therefore, ELIE provides a practical solution for the routine ranking of compounds in lead optimization.

Tyrosine Kinase 2 Signalling Drives Pathogenic T cells in Colitis

BACKGROUND AND AIMS

Tyrosine kinase 2 [TYK2] is required for the signalling of key cytokines in the pathogenesis of inflammatory bowel disease [IBD]. We assessed the efficacy of a novel selective TYK2 inhibitor [TYK2i] in experimental colitis, using pharmacological and genetic tools.

METHODS

At onset of T cell transfer colitis, RAG1-/- mice received vehicle or TYK2i daily by oral gavage. T cells lacking TYK2 kinase activity [TYK2KE] were used to confirm selectivity of the inhibitor. To this end, RAG1-/- or RAG1-/-TYK2KE animals were transferred with either wild type [WT] or TYK2KE-CD45RBhigh colitogenic T cells. Loss of body weight, endoscopic disease, the disease activity index [DAI], and histopathology scores were recorded. Tissues were analysed ex vivo for lymphocyte populations by flow cytometry. The impact of TYK2 inhibition on human DC-T cell interactions were studied using autologous Revaxis specific T cell assays.

RESULTS

TYK2i [70 mg/kg] prevented weight loss and limited endoscopic activity during T cell transfer colitis. TYK2i [70 mg/kg] decreased DAI. Whereas transfer of WT T cells into RAG-/-TYK2KE hosts induced colitis, TYK2KE T cells transferred into RAG1-/-TYK2KErecipients failed to do so. Ex vivo analysis showed a decrease in colon tissue Th1 cells and an increase in Th17 cells upon transfer of TYK2KE-CD45RBhigh cells. In human antigen-triggered T cells, TYK2i displayed reduced Th1 differentiation, similar to murine Th1 cells.

CONCLUSIONS

Oral administration of TYK2i, as well as transfer of T cells lacking TYK2 activity, reduced human Th1 differentiation and ameliorated the course of murine T cell transfer colitis. We conclude that TYK2 is a promising drug target for the treatment of IBD.

Preclinical evaluation of tyrosine kinase 2 inhibitors for human beta-cell protection in type 1 diabetes

AIM

Type 1 diabetes (T1D) is a chronic autoimmune disease leading to progressive loss of pancreatic beta cells. Interferon (IFN)-α plays a critical role in the crosstalk between pancreatic beta cells and the immune system in early insulitis. In human beta cells IFNα signals through JAK1 and TYK2, leading to endoplasmic reticulum stress, inflammation and HLA class I overexpression. IFNα, acting synergistically with IL-1β, induces apoptosis. Polymorphisms in TYK2 that decrease its activity are associated with protection against T1D, and we hypothesized that pharmacological inhibitors that specifically target TYK2 could protect human beta cells against the deleterious effects of IFNα.

MATERIALS AND METHODS

Two TYK2 inhibitors provided by Nimbus Lakshmi were tested in human insulin-producing EndoC-βH1 cells and human islets to evaluate their effect on IFNα signalling, beta-cell function and susceptibility to viral infection using RT-qPCR, western blot, immunofluorescence, ELISA and nuclear dyes.

RESULTS

The two TYK2 inhibitors tested prevented IFNα-induced human beta-cell gene expression in a dose-dependent manner. They also protected human islets against IFNα + IL-1β-induced apoptosis. Importantly, these inhibitors did not modify beta-cell function or their survival following infection with the potential diabetogenic coxsackieviruses CVB1 and CVB5.

CONCLUSIONS

The two TYK2 inhibitors tested inhibit the IFNα signalling pathway in human beta cells, decreasing its pro-inflammatory and pro-apoptotic effects without sensitizing the cells to viral infection. The preclinical findings could pave the way for future clinical trials with TYK2 inhibitors for the prevention and treatment of type 1 diabetes.

TYK2: An Upstream Kinase of STATs in Cancer

In this review we concentrate on the recent findings describing the oncogenic potential of the protein tyrosine kinase 2 (TYK2). The overview on the current understanding of TYK2 functions in cytokine responses and carcinogenesis focusses on the activation of the signal transducers and activators of transcription (STAT) 3 and 5. Insight gained from loss-of-function (LOF) gene-modified mice and human patients homozygous for Tyk2/TYK2-mutated alleles established the central role in immunological and inflammatory responses. For the description of physiological TYK2 structure/function relationships in cytokine signaling and of overarching molecular and pathologic properties in carcinogenesis, we mainly refer to the most recent reviews. Dysregulated TYK2 activation, aberrant TYK2 protein levels, and gain-of-function (GOF) TYK2 mutations are found in various cancers. We discuss the molecular consequences thereof and briefly describe the molecular means to counteract TYK2 activity under (patho-)physiological conditions by cellular effectors and by pharmacological intervention. For the role of TYK2 in tumor immune-surveillance we refer to the recent Special Issue of Cancers "JAK-STAT Signaling Pathway in Cancer".

Targeting steroid resistance in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is characterized by a variable response to steroids during induction and/or consolidation therapy. Notably, recent work suggested that these differences in glucocorticoid sensitivity might, at least in part, be mediated by hyperactivation of specific oncogenic pathways such as RAS/MEK/ERK, PI3K/AKT and IL7R/JAK/STAT. In this review, we elaborate on putative associations between aberrant signaling, therapy resistance, incidence of relapse and clinical outcome in human T-ALL. Furthermore, we emphasize that this potential association with clinical parameters might also be mediated by the tumor microenvironment as a result of increased sensitivity of leukemic T-cells towards cytokine induced signaling pathway activation. With this in mind, we provide an overview of small molecule inhibitors that might have clinical potential for the treatment of human T-ALL in the near future as a result of their ability to overcome steroid resistance thereby potentially increasing survival rates in this aggressive hematological neoplasm.

Dependency on the TYK2/STAT1/MCL1 axis in anaplastic large cell lymphoma

TYK2 is a member of the JAK family of tyrosine kinases that is involved in chromosomal translocation-induced fusion proteins found in anaplastic large cell lymphomas (ALCL) that lack rearrangements activating the anaplastic lymphoma kinase (ALK). Here we demonstrate that TYK2 is highly expressed in all cases of human ALCL, and that in a mouse model of NPM-ALK-induced lymphoma, genetic disruption of Tyk2 delays the onset of tumors and prolongs survival of the mice. Lymphomas in this model lacking Tyk2 have reduced STAT1 and STAT3 phosphorylation and reduced expression of Mcl1, a pro-survival member of the BCL2 family. These findings in mice are mirrored in human ALCL cell lines, in which TYK2 is activated by autocrine production of IL-10 and IL-22 and by interaction with specific receptors expressed by the cells. Activated TYK2 leads to STAT1 and STAT3 phosphorylation, activated expression of MCL1 and aberrant ALCL cell survival. Moreover, TYK2 inhibitors are able to induce apoptosis in ALCL cells, regardless of the presence or absence of an ALK-fusion. Thus, TYK2 is a dependency that is required for ALCL cell survival through activation of MCL1 expression. TYK2 represents an attractive drug target due to its essential enzymatic domain, and TYK2-specific inhibitors show promise as novel targeted inhibitors for ALCL.

NK Cells Require Cell-Extrinsic and -Intrinsic TYK2 for Full Functionality in Tumor Surveillance and Antibacterial Immunity

Tyrosine kinase 2 (TYK2) is a widely expressed receptor-associated kinase that is involved in signaling by a variety of cytokines with important immune regulatory activities. Absence of TYK2 in mice results in impaired NK cell maturation and antitumor activity, although underlying mechanisms are largely unknown. Using conditional ablation of TYK2 in NK cells we show that TYK2 is required for IFN-γ production by NK cells in response to IL-12 and for an efficient immune defense against Listeria monocytogenes Deletion of TYK2 in NK cells did not impact NK cell maturation and IFN-γ production upon NK cell activating receptor (actR) stimulation. Similarly, NK cell-mediated tumor surveillance was unimpaired upon deletion of TYK2 in NK cells only. In line with the previously reported maturation-associated Ifng promoter demethylation, the less mature phenotype of Tyk2^-/- NK cells correlated with an increased CpG methylation at the Ifng locus. Treatment with the DNA hypomethylating agent 5-aza-2-deoxycytidine restored the ability of Tyk2^-/- NK cells to produce IFN-γ upon actR but not upon IL-12 stimulation. NK cell maturation was dependent on the presence of TYK2 in dendritic cells and could be rescued in Tyk2-deficient mice by treatment with exogenous IL-15/IL-15Rα complexes. IL-15 treatment also rescued the in vitro cytotoxicity defect and the impaired actR-induced IFN-γ production of Tyk2^-/- NK cells. Collectively, our findings provide the first evidence, to our knowledge, for a key role of TYK2 in the host environment in promoting NK cell maturation and antitumor activity.

Selective Tyk2 inhibitors as potential therapeutic agents: a patent review (2015-2018)

INTRODUCTION

Tyrosine kinase 2 (Tyk2) is a non-receptor tyrosine-protein kinase, an enzyme that in humans is encoded by the TYK2 gene. Tyk2, together with three other family subtypes, namely, Jak1, Jak2, and Jak3, belong to the JAK family. Before 2014, far more publications and patents appeared in public domain attributing to the development of selective Jak2 and Jak3 inhibitors than those for selective Tyk2 and Jak1 inhibitors.

AREAS COVERED

This review sought to give an overview of patents related to small molecule selective Tyk2 inhibitors published from 2015 to 2018. The article also covers clinical activities of small molecule selective Tyk2 inhibitors in recent years.

EXPERT OPINION

As a key component of the JAK-STAT signaling pathway, Tyk2 regulates INFα, IL12, and IL23. Selective inhibition of Tyk2 can provide pharmacological benefits in the treatment of many diseases such as psoriasis, systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), rheumatoid arthritis (RA), cancer, and diabetes. The selectivity against other Jak family subtypes (such as Jak2) is crucial in order to minimize the potential side effects and to maximize the desired pharmacological effects. In this context, this review of recent selective Tyk2 inhibitor patents may prove valid, interesting, and promising within the therapeutic paradigm.

Targeting the immunity protein kinases for immuno-oncology

With the rise of immuno-oncology, small-molecule modulators targeting immune system and inflammatory processes are becoming a research hotspot. This work mainly focuses on key kinases acting as central nodes in immune signaling pathways. Although over thirty small-molecule kinase inhibitors have been approved by FDA for the treatment of various cancers, only a few are associated with immuno-oncology. With the going deep of the research work, more and more immunity protein kinase inhibitors are approved for clinical trials to treat solid tumors and hematologic malignancies by FDA, which remain good prospects. Meanwhile, in-depth understanding of biological function of immunity protein kinases in immune system is pushing the field forward. This article focuses on the development of safe and effective small-molecule immunity protein kinase inhibitors and further work needs to keep the promises of these inhibitors for patients' welfare.

"Do We Know Jack" About JAK? A Closer Look at JAK/STAT Signaling Pathway

Janus tyrosine kinase (JAK) family of proteins have been identified as crucial proteins in signal transduction initiated by a wide range of membrane receptors. Among the proteins in this family JAK2 has been associated with important downstream proteins, including signal transducers and activators of transcription (STATs), which in turn regulate the expression of a variety of proteins involved in induction or prevention of apoptosis. Therefore, the JAK/STAT signaling axis plays a major role in the proliferation and survival of different cancer cells, and may even be involved in resistance mechanisms against molecularly targeted drugs. Despite extensive research focused on the protein structure and mechanisms of activation of JAKs, and signal transduction through these proteins, their importance in cancer initiation and progression seem to be underestimated. This manuscript is an attempt to highlight the role of JAK proteins in cancer biology, the most recent developments in targeting JAKs, and the central role they play in intracellular cross-talks with other signaling cascades.

Translational and clinical advances in JAK-STAT biology: The present and future of jakinibs

In this era, it is axiomatic that cytokines have critical roles in cellular development and differentiation, immune homeostasis, and host defense. Equally, dysregulation of cytokines is known to contribute to diverse inflammatory and immune-mediated disorders. In fact, the past 20 years have witnessed the rapid translation of basic discoveries in cytokine biology to multiple successful biological agents (mAbs and recombinant fusion proteins) that target cytokines. These targeted therapies have not only fundamentally changed the face of multiple immune-mediated diseases but have also unequivocally established the role of specific cytokines in human disease; cytokine biologists have many times over provided remarkable basic advances with direct clinical benefit. Numerous cytokines rely on the JAK-STAT pathway for signaling, and new, safe, and effective small molecule inhibitors have been developed for a range of disorders. In this review, we will briefly summarize basic discoveries in cytokine signaling and briefly comment on some major unresolved issues. We will review clinical data pertaining to the first generation of JAK inhibitors and their clinical indications, discuss additional opportunities for targeting this pathway, and lay out some of the challenges that lie ahead.

B lymphoblastic leukemia/lymphoma: new insights into genetics, molecular aberrations, subclassification and targeted therapy

B lymphoblastic leukemia/lymphoma (B-ALL) is a clonal hematopoietic stem cell neoplasm derived from B-cell progenitors, which mostly occurs in children and adolescents and is regarded as one of top leading causes of death related to malignancies in this population. Despite the majority of patients with B-ALL have fairly good response to conventional chemotherapeutic interventions followed by hematopoietic stem cell transplant for the last decades, a subpopulation of patients show chemo-resistance and a high relapse rate. Adult B-ALL exhibits similar clinical course but worse prognosis in comparison to younger individuals. Ample evidences have shown that the clinical behavior, response rate and clinical outcome of B-ALL rely largely on its genetic and molecular profiles, such as the presence of BCR-ABL1 fusion gene which is an independent negative prognostic predictor. New B-ALL subtypes have been recognized with recurrent genetic abnormalities, including B-ALL with intrachromosomal amplification of chromosome 21 (iAMP21), B-ALL with translocations involving tyrosine kinases or cytokine receptors (“BCR-ABL1-like ALL”). Genome-wide genetic profiling studies on B-ALL have extended our understanding of genomic landscape of B-ALL, and genetic mutations involved in various key pathways have been illustrated. These include CRLF2 and PAX5 alterations, TP53, CREBBP and ERG mutations, characteristic genetic aberrations in BCR-ABL1-like B-ALL and others. The review further provides new insights into clinical implication of the genetic aberrations in regard to targeted therapy development.

From the outside, from within: Biological and therapeutic relevance of signal transduction in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological cancer that arises from clonal expansion of transformed T-cell precursors. In this review we summarize the current knowledge on the external stimuli and cell-intrinsic lesions that drive aberrant activation of pivotal, pro-tumoral intracellular signaling pathways in T-cell precursors, driving transformation, leukemia expansion, spread or resistance to therapy. In addition to their pathophysiological relevance, receptors and kinases involved in signal transduction are often attractive candidates for targeted drug development. As such, we discuss also the potential of T-ALL signaling players as targets for therapeutic intervention.