Development of new pyrrolopyrimidine-based inhibitors of Janus kinase 3 (JAK3)

Discovery of diaminopyrimidine-carboxamide derivatives as JAK3 inhibitors

Selective inhibition of janus kinase (JAK) has been identified as an important strategy for the treatment of autoimmune disorders. Optimization at the C2 and C4-positions of pyrimidine ring of Cerdulatinib led to the discovery of a potent and orally bioavailable 2,4-diaminopyrimidine-5-carboxamide based JAK3 selective inhibitor (11i). A cellular selectivity study further confirmed that 11i preferentially inhibits JAK3 over JAK1, in JAK/STAT signaling pathway. Compound 11i showed good anti-arthritic activity, which could be correlated with its improved oral bioavailability. In the repeat dose acute toxicity study, 11i showed no adverse changes related to gross pathology and clinical signs, indicating that the new class JAK3 selective inhibitor could be viable therapeutic option for the treatment of rheumatoid arthritis.

Putative dual inhibitors of Janus kinase 1 and 3 (JAK1/3): Pharmacophore based hierarchical virtual screening

Janus kinase 1 and 3 are non-receptor protein tyrosine kinases, involved in the regulation of various cytokines implicated in the pathogenesis of autoimmune and inflammatory disease conditions. Thus, they serve as therapeutic targets for the designing of multi-targeted agents for the treatment of inflammatory-mediated pathological conditions. In the present study, diverse inhibitors of JAK1 and JAK3 were considered for the development of ligand-based pharmacophore models, followed by docking analysis to design putative dual inhibitors. The pharmacophore models were generated in PHASE 3.4, and top five models for each target were selected on the basis of survival minus inactive score. The best model for JAK1 (AAADH.25) and JAK3 (ADDRR.142) were selected corresponding to the highest value of Q²_test. Both models were employed for the screening of a PHASE database, and subsequently, the retrieved hits were filtered employing molecular docking in JAK1 and JAK3 proteins. The stable interactions between retrieved hits and proteins were confirmed using molecular dynamics simulations. Finally, ADME properties of screened dual inhibitors displaying essential interactions with both proteins were calculated. Thus, the new leads obtained in this way may be prioritized for experimental validation as potential novel therapeutic agents in the treatment of various autoimmune and inflammatory disorders related to JAK1 and JAK3.

Molecular dynamics and integrated pharmacophore-based identification of dual [Formula: see text] inhibitors

Despite increase in the understanding of the pathogenesis of rheumatoid arthritis (RA), it remains a tough challenge. The advent of kinases involved in key intracellular pathways in pathogenesis of RA may provide a new phase of drug discovery for RA. The present study is aimed to identify dual JAK3/[Formula: see text] inhibitors by developing an optimum pharmacophore model integrating the information revealed by ligand-based pharmacophore models and structure-based pharmacophore models (SBPMs). For JAK3 inhibitors, the addition of an aromatic ring feature and for [Formula: see text] the addition of a hydrophobic feature proposed by SBPMs lead to five-point pharmacophore (i.e., AADHR.54 (JAK3)) and six-point pharmacophore (i.e., AAAHRR.45 ([Formula: see text])). The obtained pharmacophores were validated and used for virtual screening and then for docking-based screening. Molecules were further evaluated for ADME properties, and their docked protein complexes were subjected to MM-GBSA energy calculations and molecular dynamic simulations. The top two hit compounds with novel scaffolds 2-oxo-1,2-dihydroquinoline and benzo[d]oxazole showed inhibitory activity for JAK3 and [Formula: see text].

Ligand-based and e-pharmacophore modeling, 3D-QSAR and hierarchical virtual screening to identify dual inhibitors of spleen tyrosine kinase (Syk) and janus kinase 3 (JAK3)

The clinical efficacy of multiple kinase inhibitors has caught the interest of Pharmaceutical and Biotech researchers to develop potential drugs with multi-kinase inhibitory activity for complex diseases. In the present work, we attempted to identify dual inhibitors of spleen tyrosine kinase (Syk) and janus kinase 3 (JAK3), keys players in immune signaling, by developing ideal pharmacophores integrating Ligand-based pharmacophore models (LBPMs) and Structure-based pharmacophore models (SBPMs), thereby projecting the optimum pharmacophoric required for inhibition of both the kinases. The four point LBPM; ADPR.14 suggested the presence of one hydrogen bond acceptor, one hydrogen bond donor, one positive ionizable, and one ring aromatic feature for Syk inhibitory activity and AADH.54 proposed the necessity of two hydrogen bond acceptor, one hydrogen bond donor, and one hydrophobic feature for JAK3 inhibitory activity. To our interest, SBPMs identified additional ring aromatic features required for inhibition of both the kinases. For Syk inhibitory activity, the hydrogen bond acceptor feature indicated by LBPM was devoid of forming hydrogen bonding interaction with the hinge region amino acid residue (Ala451). Thus merging the information revealed by both LBPMs and SBPMs, ideal pharmacophore models i.e. ADPRR.14 (Syk) and AADHR.54 (JAK3) were generated. These models after rigorous statistical validation were used for screening of Asinex database. The systematic virtual screening protocol, including pharmacophore and docking-based screening, ADME property, and MM-GBSA energy calculations, retrieved final 10 hits as dual inhibitors of Syk and JAK3. Final 10 hits thus obtained can aid in the development of potential therapeutic agents for autoimmune disorders. Also the top two hits were evaluated against both the enzymes.

Identification of Purines and 7-Deazapurines as Potent and Selective Type I Inhibitors of Troponin I-Interacting Kinase (TNNI3K)

A series of cardiac troponin I-interacting kinase (TNNI3K) inhibitors arising from 3-((9H-purin-6-yl)amino)-N-methyl-benzenesulfonamide (1) is disclosed along with fundamental structure-function relationships that delineate the role of each element of 1 for TNNI3K recognition. An X-ray structure of 1 bound to TNNI3K confirmed its Type I binding mode and is used to rationalize the structure-activity relationship and employed to design potent, selective, and orally bioavailable TNNI3K inhibitors. Identification of the 7-deazapurine heterocycle as a superior template (vs purine) and its elaboration by introduction of C4-benzenesulfonamide and C7- and C8-7-deazapurine substituents produced compounds with substantial improvements in potency (>1000-fold), general kinase selectivity (10-fold improvement), and pharmacokinetic properties (>10-fold increase in poDNAUC). Optimal members of the series have properties suitable for use in in vitro and in vivo experiments aimed at elucidating the role of TNNI3K in cardiac biology and serve as leads for developing novel heart failure medicines.

Crystal structure of bis-[4-(1H-pyrrol-1-yl)phen-yl] ferrocene-1,1'-di-carboxyl-ate: a potential chemotherapeutic drug

The title iron(II) complex, [Fe(C16H12NO2)2], crystallizes in the ortho-rhom-bic space group Pbca with the Fe(2+) cation positioned on an inversion center. The cyclo-penta-dienyl (Cp) rings adopt an anti conformation in contrast with other substituted ferrocenes in which the Cp rings appear in a nearly eclipsed conformation. The Cp and the aromatic rings are positioned out of the plane, with a twist angle of 70.20 (12)°, and the C(Cp)-C(CO) bond length is shorter than a typical C-C single bond, which suggests a partial double-bond character and delocalization with the Cp π system. The structure of the complex is compared to other functionalized ferrocenes synthesized in our laboratory.

Ferrocenes as potential chemotherapeutic drugs: synthesis, cytotoxic activity, reactive oxygen species production and micronucleus assay

Three new ferrocene complexes were synthesized with 4-(1H-pyrrol-1-yl)phenol group appended to one of the Cp ring. These are: 1,1'-4-(1H-pyrrol-1-yl)phenyl ferrocenedicarboxylate, ('Fc-(CO2-Ph-4-Py)2'), 1,4-(1H-pyrrol-1-yl)phenyl, 1'-carboxyl ferrocenecarboxylate ('Fc-(CO2-Ph-4-Py)CO2H') and 4-(1H-pyrrol-1-yl)phenyl ferroceneacetylate ('Fc-CH2CO2-Ph-4-Py'). The new species were characterized by standard analytical methods. Cyclic voltammetry experiments showed that Fc-CH2CO2-Ph-4-Py has redox potential very similar to the Fc/Fc(+) redox couple whereas Fc-(CO2-Ph-4-Py)2 and Fc-(CO2-Ph-4-Py)CO2H have redox potentials of over 400 mV higher than Fc/Fc(+) redox couple. The in vitro studies on Fc-(CO2-Ph-4-Py)2 and Fc-(CO2-Ph-4-Py)CO2H revealed that these two compounds have moderate anti-proliferative activity on MCF-7 breast cancer cell line. In contrast Fc-CH2CO2-Ph-4-Py which displayed low anti-proliferative activity. In the HT-29 colon cancer cell line, the new species showed low anti-proliferative activity. Cytokinesis-block micronucleus assay (CBMN) was performed on these ferrocenes and it was determined they induce micronucleus formation on binucleated cells and moderate genotoxic effects on the MCF-7 breast cancer cell line. There is a correlation between the IC50 values of the ferrocenes and the amount of micronucleus formation activity on binucleated cells and the reactive oxygen species (ROS) production on MCF-7 cell line.

Tricyclic covalent inhibitors selectively target Jak3 through an active site thiol

The action of Janus kinases (JAKs) is required for multiple cytokine signaling pathways, and as such, JAK inhibitors hold promise for treatment of autoimmune disorders, including rheumatoid arthritis, inflammatory bowel disease, and psoriasis. However, due to high similarity in the active sites of the four members (Jak1, Jak2, Jak3, and Tyk2), developing selective inhibitors within this family is challenging. We have designed and characterized substituted, tricyclic Jak3 inhibitors that selectively avoid inhibition of the other JAKs. This is accomplished through a covalent interaction between an inhibitor containing a terminal electrophile and an active site cysteine (Cys-909). We found that these ATP competitive compounds are irreversible inhibitors of Jak3 enzyme activity in vitro. They possess high selectivity against other kinases and can potently (IC50 < 100 nm) inhibit Jak3 activity in cell-based assays. These results suggest irreversible inhibitors of this class may be useful selective agents, both as tools to probe Jak3 biology and potentially as therapies for autoimmune diseases.

Crystal structures of 4-(pyrimidin-2-yl)piperazin-1-ium chloride and 4-(pyrimidin-2-yl)piperazin-1-ium nitrate

The title salts, C8H13N4 (+)·Cl(-), (I), and C8H13N4 (+)·NO3 (-), (II), contain linked pyridinium-piperazine heterocycles. In both salts, the piperazine ring adopts a chair conformation with protonation at the N atom not linked to the other ring. In the crystal of (I), weak N-H⋯Cl inter-actions are observed, leading to zigzag chains along [100]. In the crystal of (II), both H atoms on the NH2 (+) group form bifurcated N-H⋯(O,O) hydrogen bonds. Weak C-H⋯O inter-actions are also observed. These bonds collectively link the components into infinite chains along [100].

Carbonic anhydrase inhibitors: Synthesis, molecular docking, cytotoxic and inhibition of the human carbonic anhydrase isoforms I, II, IX, XII with novel benzenesulfonamides incorporating pyrrole, pyrrolopyrimidine and fused pyrrolopyrimidine moieties

A series of novel pyrroles, pyrrolopyrimidines, pyrazolopyrrolopyrimidine, triazolopyrrolopyrimidines, tetrazolopyrrolopyrimidine, triazinopyrrolopyrimidines and pyrrolopyrimidotriazepines bearing the biologically active benzenesulfonamide moiety were synthesized by using pyrrole-o-amino-carbonitrile as key intermediate. All the synthesized compounds were evaluated for their in vitro carbonic anhydrase (CA, EC 4.2.1.1) inhibitory effects against the human (h) isoforms hCA I, II, IX and XII. Among the tested derivatives, compounds 16, 18 and 20-24 showed potent activity as inhibitors for the tumor associated transmembrane isoforms (hCA IX and XII) in the nanomolar and subnanomolar range, with high selectivity. All compounds underwent cytotoxic activity assays on human breast cancer cell line (MCF-7) showing effective activity, comparable to that of the clinically used drug doxorubicin.

4-(Pyrimidin-2-yl)piperazin-1-ium (E)-3-carb-oxy-prop-2-enoate

In the cation of the title salt, C8H13N4 (+)·C4H3O4 (-), the piperazinium ring adopts a slightly distorteded chair conformation. In the crystal, a single strong O-H⋯O inter-molecular hydrogen bond links the anions, forming chains along the c-axis direction. The chains of anions are linked by the cations, via N-H⋯O hydrogen bonds, forming sheets parallel to (100). These layers are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional structure. In addition, there are weak π-π inter-actions [centroid-centroid distance = 3.820 (9) Å] present involving inversion-related pyrimidine rings.

Pharmacophore and Virtual Screening of JAK3 inhibitors

Janus kinase 3 (JAK3) is a non-receptor tyrosine kinases family of protein which is comprised of JAK1, JAK2, JAK3 and TYK2. It plays an important role in immune function and lymphoid development and it only resides in the hematopoietic system. Therefore, selective targeting JAK3 is a rational approach in developing new therapeutic molecule. In this study, about 116 JAK3 inhibitors were collected from the literature and were used to build four-point pharmacophore model using Phase (Schrodinger module). The statistically significant pharmacophore hypothesis of AAHR.92 with r2 value of 0.942 was used as 3D query to search against 3D database namely Zincpharmer. A total of 2, 27,483 compounds obtained as hit were subjected to high throughput virtual screening (HTVS module of Schrodinger). Among the hits, ten compounds with good G-score ranging from -12.96 to -11.18 with good binding energy to JAK3 were identified.

New chemical scaffolds for human african trypanosomiasis lead discovery from a screen of tyrosine kinase inhibitor drugs

Human African trypanosomiasis (HAT) is caused by the protozoan Trypanosoma brucei. New drugs are needed to treat HAT because of undesirable side effects and difficulties in the administration of the antiquated drugs that are currently used. In human proliferative diseases, protein tyrosine kinase (PTK) inhibitors (PTKIs) have been developed into drugs (e.g., lapatinib and erlotinib) by optimization of a 4-anilinoquinazoline scaffold. Two sets of facts raise a possibility that drugs targeted against human PTKs could be "hits" for antitrypanosomal lead discoveries. First, trypanosome protein kinases bind some drugs, namely, lapatinib, CI-1033, and AEE788. Second, the pan-PTK inhibitor tyrphostin A47 blocks the endocytosis of transferrin and inhibits trypanosome replication. Following up on these concepts, we performed a focused screen of various PTKI drugs as possible antitrypanosomal hits. Lapatinib, CI-1033, erlotinib, axitinib, sunitinib, PKI-166, and AEE788 inhibited the replication of bloodstream T. brucei, with a 50% growth inhibitory concentration (GI50) between 1.3 μM and 2.5 μM. Imatinib had no effect (i.e., GI50>10 μM). To discover leads among the drugs, a mouse model of HAT was used in a proof-of-concept study. Orally administered lapatinib reduced parasitemia, extended the survival of all treated mice, and cured the trypanosomal infection in 25% of the mice. CI-1033 and AEE788 reduced parasitemia and extended the survival of the infected mice. On the strength of these data and noting their oral bioavailabilities, we propose that the 4-anilinoquinazoline and pyrrolopyrimidine scaffolds of lapatinib, CI-1033, and AEE788 are worth optimizing against T. brucei in medicinal chemistry campaigns (i.e., scaffold repurposing) to discover new drugs against HAT.

Dual inhibitors of Janus kinase 2 and 3 (JAK2/3): designing by pharmacophore- and docking-based virtual screening approach

JAK2 and JAK3 are non-receptor protein tyrosine kinases implicated in B-cell- and T-cell-mediated diseases. Both enzymes work via different pathways but are involved in the pathogenesis of common lymphoid-derived diseases. Hence, targeting both Janus kinases together can be a potential strategy for the treatment of these diseases. In the present study, two separate pharmacophore-based 3D-QSAR models ADRR.92 (Q(2)(test)0.663, R(2)(train) 0.849, F value 219.3) for JAK2 and ADDRR.142 (Q(2)(test)0.655, R(2)(train) 0.869, F value 206.9) for JAK3 were developed. These models were employed for the screening of a PHASE database of approximately 1.5 million compounds; subsequently, the retrieved hits were screened employing docking simulations with JAK2 and JAK3 proteins. Finally, ADME properties of screened dual inhibitors displaying essential interactions with both proteins were calculated to filter candidates with poor pharmacokinetic profiles. These candidates could serve as novel therapeutic agents in the treatment of lymphoid-related diseases.

Advances in the discovery of selective JAK inhibitors

In this review, we describe the current knowledge of the biology of the JAKs. The JAK family comprises the four nonreceptor tyrosine kinases JAK1, JAK2, JAK3, and Tyk2, all key players in the signal transduction from cytokine receptors to transcription factor activation. We also review the progresses made towards the optimization of JAK inhibitors and the importance of their selectivity profile. Indeed, the full array of many medicinal chemistry enabling tools (HTS, X-ray crystallography, scaffold morphing, etc.) has been deployed to successfully design molecules that discriminate among JAK family and other kinases. While the first JAK inhibitor was launched in 2011, this review also summarizes the status of several other small-molecule JAK inhibitors currently in development to treat arthritis, psoriasis, organ rejection, and multiple cancer types.

Thioxopyrimidine in Heterocyclic Synthesis I: Synthesis of Some Novel 6-(Heteroatom-substituted)-(thio)pyrimidine Derivatives

A series of novel N-cycloalkanes, morpholine, piperazines, pyrazole, pyrimidine, benzimidazolo[1,2-a]pyrimidine, 1,2,3,4-tetrazolo[1,5-a]pyrimidine, azopyrazolo[1,5- a]pyrimidine, pyrimido[4', 5':3,4]pyrazolo[1,5-a]pyrimidines and pyridine derivatives incorporating a 5-cyano-4-methyl-2-phenyl-(thio)pyrimidine moiety were obtained by the intramolecular cyclization of 6-methylthio-pyrimidine, 6-(benzoylmethyl)thio- pyrimidine and 2-[(5-cyano-4-methyl-2-phenylpyrimidin-6-yl)thio]-3-dimethyl- amino-1-phenyl-prop-2-en-1-one with appropriate amines and enaminone compounds, respectively. The structure of all new synthesized compounds was established from their spectral data, elemental analysis and the X-ray crystal analysis.

The Use of JAK-specific inhibitors as chemical biology tools

The JAK family of protein tyrosine kinases are now recognized as important participants in a wide range of pathologies, from cancer to inflammatory diseases. In the last decade, the drive to develop drugs targeting members of this family has begun to deliver a panel of small molecule inhibitors of JAK family members, with a range of potencies and specificities. A number of these compounds have already found widespread use as biochemical tools in the elucidation of JAK activity in specific signaling and disease processes; however, many of the first generation compounds are poorly characterized with suboptimal potencies and selectivities.Herein, we present the data for those small molecule JAK inhibitors that have been described in the peer-reviewed literature and the benefits and potential issues that may be associated with the use of these tool compounds.

Novel pyrrolopyrimidine-based α-helix mimetics: cell-permeable inhibitors of protein−protein interactions

There is considerable interest in developing non-peptidic, small-molecule α-helix mimetics to disrupt α-helix-mediated protein−protein interactions. Herein, we report the design of a novel pyrrolopyrimidine-based scaffold for such α-helix mimetics with increased conformational rigidity. We also developed a facile solid-phase synthetic route that is amenable to divergent synthesis of a large library. Using a fluorescence polarization-based assay, we identified cell-permeable, dual MDMX/MDM2 inhibitors, demonstrating that the designed molecules can act as α-helix mimetics.

Targeting signaling pathways with small molecules to treat autoimmune disorders

Chronic activation of immune responses, mediated by inflammatory mediators and involving different effector cells of the innate and acquired immune system characterizes autoimmune disorders, such as rheumatoid arthritis, inflammatory bowel disease, psoriasis and septic shock syndrome. MAPKs are crucial intracellular mediators of inflammation. MAPK inhibitors are attractive anti-inflammatory drugs, because they are capable of reducing the synthesis of inflammation mediators at multiple levels and are effective in blocking proinflammatory cytokine signaling. Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway converts cytokine signals into genomic responses regulating proliferation and differentiation of the immune cells. JAK inhibitors are a new class of immunomodulatory agents with immunosuppressive, anti-inflammatory and antiallergic properties. This review discusses the rationale behind current strategies of targeting MAPK and JAK/STAT signaling pathways, and the overall effects of signal transduction inhibitors in animal models of inflammatory disorders. Signal transduction inhibitors are small molecules that can be administered orally, and initial results of clinical trials have shown clinical benefits in patients with chronic inflammatory disorders.

Perspectives for the use of structural information and chemical genetics to develop inhibitors of Janus kinases

Gain-of-function mutations in the genes encoding Janus kinases have been discovered in various haematologic diseases. Jaks are composed of a FERM domain, an SH2 domain, a pseudokinase domain and a kinase domain, and a complex interplay of the Jak domains is involved in regulation of catalytic activity and association to cytokine receptors. Most activating mutations are found in the pseudokinase domain. Here we present recently discovered mutations in the context of our structural models of the respective domains. We describe two structural hotspots in the pseudokinase domain of Jak2 that seem to be associated either to myeloproliferation or to lymphoblastic leukaemia, pointing at the involvement of distinct signalling complexes in these disease settings. The different domains of Jaks are discussed as potential drug targets. We present currently available inhibitors targeting Jaks and indicate structural differences in the kinase domains of the different Jaks that may be exploited in the development of specific inhibitors. Moreover, we discuss recent chemical genetic approaches which can be applied to Jaks to better understand the role of these kinases in their biological settings and as drug targets.

A novel indole-3-propanamide exerts its immunosuppressive activity by inhibiting JAK3 in T cells

We previously identified an indole-3-propanamide derivative, 3-[1-(4-chlorobenzyl)indol-3-yl]-N-(pyridin-4-yl)propanamide (AD412), as a potential immunosuppressive agent. Here, we document that AD412 inhibited the proliferative response of CD3/CD28-stimulated human T cells without inhibiting their interleukin 2 (IL-2) production and also inhibited the proliferation of CTL-L2 cells in response to IL-2. These results prompted us to analyze the effect of our compound on the three main signaling pathways coupled to the IL-2 receptor. We provide evidence that AD412 inhibited the JAK1/3-dependent phosphorylations of Akt, STAT5a/b, and ERK1/2 in IL-2-stimulated CTL-L2 cells. In contrast, AD412 had little effect on the JAK1/2-dependent INF-gamma-induced phosphorylation of STAT1 in U266 cells. This suggested a preferential inhibition of JAK3 over JAK1 or JAK 2 activities by AD412 that was confirmed by in vitro kinase assays with purified JAK2 and JAK3 kinases. In addition, we provide evidence that the inhibition of IL-2 response by AD412 was not due to inhibition of IL-2Ralpha up-regulation because neither AD412 nor JAK3 inhibitors described previously [4-[(3-bromo-4-hydroxyphenyl)amino]-6,7-dimethoxyquinazoline (WHI-P154) and alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamid (AG-490)] significantly inhibited IL-2-induced IL-2Ralpha overexpression. Finally, we further document the immunosuppressive activity of AD412 in vivo by showing that its administration per os significantly prolonged heart allograft graft survival. This molecule may thus represent an interesting lead compound to develop new immunosuppressive agents in the field of transplantation and autoimmune diseases.

Diversity oriented syntheses of fused pyrimidines designed as potential antifolates

Diversity oriented syntheses of some furo[2,3-d]pyrimidines and pyrrolo[2,3-d]pyrimidines related to folate, guanine, and diaminopyrimidine-containing drugs have been developed for the preparation of potential anti-infective and anticancer compounds. Amide couplings and Suzuki couplings on the basic heterocyclic templates were used, in the latter case yields being especially high using aromatic trifluoroborates as the coupling partner. A new ring synthesis of 6-aryl-substituted deazaguanines bearing 2-alkylthio groups has been developed using Michael addition of substituted nitrostyrenes. Diversity at C-2 has been introduced by oxidation and substitution with a range of amino nucleophiles. The chemical reactivity of these pyrrolopyrimidines with respect to both electrophilic substitution in ring synthesis and nucleophilic substitution for diversity is discussed. Several compounds were found to inhibit pteridine reductases from the protozoan parasites Trypanosoma brucei and Leishmania major at the micromolar level and to inhibit the growth of Trypanosma brucei brucei in cell culture at higher concentrations. From these results, significant structural features required for inhibition of this important drug target enzyme have been identified.

Kinase inhibitors for the treatment of inflammatory and autoimmune disorders

Drugs targeting inhibition of kinases for the treatment of inflammation and autoimmune disorders have become a major focus in the pharmaceutical and biotech industry. Multiple kinases from different pathways have been the targets of interest in this endeavor. This review describes some of the recent developments in the search for inhibitors of IKK2, Syk, Lck, and JAK3 kinases. It is anticipated that some of these compounds or newer inhibitors of these kinases will be approved for the treatment of rheumatoid arthritis, psoriasis, organ transplantation, and other autoimmune diseases.