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`v.20 no 11 (Nov 2010)
`General Collection
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`SAN EX 1005, Page 1
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`

`

`
`
`Ex ert
`
`Opiifi'on on Therapeutic Patents
`
`
`
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`Advisory Panel
`Krogsgaard-Larsen P, Poste G, Steele PR,
`Stevens RW, Terrett N,
`Tlmmermanns P, Warburg R
`
`Pulmonary—Allergy, Dermatological,
`Gastrointestinal & Arthritis
`Dominguez C, Murthy S,
`Norman P, Whittaker M
`Anti-infectives
`Chand P, Cooper RDG, Croft S, Hector RF,
`Hunter PA, Kirst H, Lee VJ, Nwaka S,
`Supuran C
`
`Biologicals, Immunologicals &
`Drug Delivery
`Deonarain M P, Dumont F, Martini A
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`Central 8: Peripheral Nervous Systems
`Christos T, Clifie l, Dziadulewicz E, Hill C,
`Lightfoot AP, Suto M
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`Cardiovascular, Renal, Endocrine 8i
`Metabolic
`Dueholm KL, Hill C, Jacobson KA, Laight DW,
`Muller CE. Remuzzi G, Sattigeri l, Suckling KE
`
`Oncologic
`Dalgleish A, Ecker G, Garrett M, Marx MA,
`McCubrey JA, Myles D, Sawyer T, Supuran C
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`.
`Aims and scope
`Expert Opinion on Therapeutic Patents is a peer-reviewed, international journal publishing
`review articles on recent pharmaceutical patent claims, providing expert opinion the scope
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`The Editors welcome:
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`2010 (0 lnlorma UK, Ltd. iSSN 13543776
`
`SAN EX 1005, Page 2
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`

`

`November 2010 Vol. 20 No. 11
`
`Expert
`Opinion on Therapeutic Patents
`
`
`
`1573
`
`Update on lymphocyte specific
`kinase inhibitors: a patent survey
`MW Martin 8: MR Machacek
`
`Forthcoming articles
`I Biologicals targeting s‘urvivin: a patent review
`o
`inhibitors 01 Anaplasuc Lymphoma Kinase: a
`patent review
`. Spiro azepane-oxazolidinones as Kv1.3
`tassium channel blockers -
`02010066840
`0 Thirteen compounds promotin
`oligodendrocyte progenitor cel
`dil ercn’tlation and remyelination for
`treating multiple sclerosis
`
`Reviews
`1429 S-HTZC receptor modulators:
`a patent survey
`J Lee, ME Jung & J Lee
`1457 Bruton’s tyrosine kinase as a
`molecular target in treatment of
`leukemias and lymphomas as
`well as inflammatory disorders
`and autoimmunity
`FM Uckun 81 5 Qazi
`
`1471 Pharmacological modulation
`of voltage-gated potassium
`channels as a therapeutic
`strategy
`NA Castle
`
`1505 Novel CRTHZ antagonists: a
`review of patents from 2006
`to 2009
`T Ulven & E Kostenis
`
`1531 Recent developments in the
`inhibitors of neuroinflammation
`and neurodegeneration:
`inflammatory oxidative enzymes
`as a drug target
`DK Choi, S Koppula, M Choi &
`K Suk
`
`1547 Strategies for proprotein
`convertase subtilisin kexin 9
`modulation: a perspective on
`recent patents
`M Ab/fadel, J Pakradouni, M Col/in,
`M—E 5amson~Bouma, M Varret,
`J—P Rabes & C Boileau
`
`Annotated Patent Selections
`1595
`Pulmonary-Allergy,
`Dermatological, Gastrointestinal
`& Arthritis
`Anti-infectives
`Biologicais, lmmunologicals &
`Drug Delivery
`Central & Peripheral Nervous
`System
`Cardiovascular, Renal, Endocrine
`& Metabolism
`Oncology
`
`1596
`1597
`
`1598
`
`1599
`
`1600
`
`Patent Evaluations
`1603
`Methods for synthesis and uses
`of inhibitors of Ghrelin
`O—acyltransferase inhibitors as
`potential therapeutic agents for
`obesity and diabetes
`L Costantino
`
`1609
`
`N—aryl pyrazoles, indazoles and
`azaindazoles as antagonists of
`CC chemokine receptor 1: patent
`cooperation treaty applications
`W02010/036632, W02009/
`134666 and W02009/l37338
`PH Carter & J Hynes
`
`informa
`healthcare
`
`Expert Opinion on Therapeutic Patents is grateful and indebted to
`the reviewers of all the above articles
`
`2010 © lnlorma UK. Ltd. ISSN 1354-3776
`
`SAN EX 1005, Page 3
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`SAN EX 1005, Page 3
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`

`

`1.
`
`2.
`
`3.
`
`4.
`
`5.
`
`6.
`
`7.
`
`Protein tyrosine kinases as
`molecular targets for new
`drugs
`
`BTK
`
`BTK as an
`anti-apoptotic molecular
`target in cancer
`
`BTK as a molecular target in
`GVHD
`
`BTK as a molecular target in
`thromboembolism
`
`BTK as a molecular target in
`inflammatory disorders
`
`Small molecule inhibitors of
`BTK
`
`8.
`
`Expert opinion
`
`Review
`
`Bruton’s tyrosine kinase as a
`molecular target in treatment of
`leukemias and lymphomas as well
`as inflammatory disorders and
`autoimmunity
`
`†
`& Sanjive Qazi
`Fatih M Uckun
`†
`University of Southern California Keck School of Medicine, Children’s Center for Cancer and
`Blood Diseases, Division of Hematology-Oncology, Department of Pediatrics, Los Angeles, CA, USA
`
`Importance of the field: Bruton’s tyrosine kinase (BTK) has emerged as a
`new anti-apoptotic molecular target for the treatment of B-lineage leukemias
`and lymphomas. Preclinical and early clinical results indicate that BTK
`inhibitors may be useful in the treatment of leukemias and lymphomas. BTK
`inhibitors may also be helpful in prevention and treatment of thromboembolic
`complications as well as inflammatory disorders.
`Areas covered in this review: We provide a comprehensive review of the tar-
`get diseases for which the use of BTK inhibitors may be helpful as well as the
`activity profiles of BTK inhibitors.
`What the reader will gain: We review the currently available translational
`research, biomarker as well as patent literature regarding BTK molecular
`target and BTK inhibitors.
`Take home message: BTK inhibitors may provide the foundation for thera-
`peutic innovation against B-lineage leukemias/lymphomas,
`inflammatory
`disorders and autoimmunity.
`
`Keywords: Bruton’s tyrosine kinase, graft-versus-host disease, inflammatory disorders, leukemia,
`lymphoma, rational drug design, thromboembolism
`
`Expert Opin. Ther. Patents (2010) 20(11):1457-1470
`
`1. Protein tyrosine kinases as molecular targets for new
`drugs
`
`More than 200 member genes of the protein kinase complement of the human
`genome -- ‘kinome’ -- have been mapped to disease loci or cancer amplicons [1,2].
`Among the kinases encoded by the ‘kinome’, ~ 100 are protein tyrosine kinases
`(PTK) that play important regulatory roles in intracellular signal transduction
`pathways affecting survival, proliferation and chemotherapy sensitivity of cancer
`cells. Small molecule inhibitors of these PTK have emerged as promising new
`anticancer drug candidates [3-8]. There is a wealth of crystal structure information
`of protein kinase and inhibitor complexes that provides the basis for the structur-
`e--activity relationships of kinase inhibitors [3-8]. Figure 1A shows the binding
`modes of small-molecule protein kinase inhibitors in relationship to the hinge
`regions of the ATP-binding site in view with the N-lobe on the top and the
`C-lobe in the background, based on corresponding crystal structures (taken
`from the coordinates with PDB access codes: 1fvt, 1a9u, 1fpu, 2csn, 1ian, 1di8,
`1aq1, 1ckp, 1bl6, 1bl7, 1k2p). Figure 1B shows a model of the ternary complex
`
`10.1517/13543776.2010.517750 © 2010 Informa UK, Ltd. ISSN 1354-3776
`All rights reserved: reproduction in whole or in part not permitted
`
`1457
`
`SAN EX 1005, Page 4
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`

`

`Bruton’s tyrosine kinase as a molecular target in treatment
`
`Article highlights.
`
`. BTK has emerged as an upstream activator of multiple
`anti-apoptotic signaling molecules and networks.
`. A meta-analysis of cancer-associated gene expression
`changes revealed a marked enrichment of the most
`discriminating BTK-dependent anti-apoptotic gene
`targets for human leukemias and lymphomas.
`. The availability of the coordinates of the BTK kinase
`domain X-ray crystal structures supports the
`development of rationally designed BTK inhibitors.
`. BTK inhibitors show potential as anti-leukemic
`agents with apoptosis-promoting and
`chemosensitizing properties.
`. BTK inhibitors also show potential as
`immunomodulatory agents for treatment of
`autoimmune diseases, inflammatory disorders,
`graft-versus-host disease in hematopoietic stem cell
`transplantation and treatment/prevention of
`thromboembolism.
`
`This box summarizes key points contained in the article.
`
`of Bruton’s tyrosine kinase (BTK) (blue), ATP (multiple
`colors) and a peptide substrate (white) derived from the crys-
`tal structure of the BTK kinase domain. Figure 1C is a sche-
`matic illustration of the active site. There are two hydrogen
`acceptors and one hydrogen donor from the backbone car-
`bonyl and amide groups of the hinge region, potentially
`forming hydrogen bonds with the inhibitors (as indicated
`by arrows in B) which, aligned with the ATP-binding cleft,
`determine the orientation of protein kinase inhibitors.
`Many derivatives of tyrosine kinase inhibitors that contain
`the same core groups would be expected to adopt one of
`these binding modes with 1 -- 3 hydrogen bonds with the
`protein backbone.
`
`2. BTK
`
`the SRC-related TEC family of
`BTK is a member of
`cytoplasmic PTK [9-11]. TEC family kinases are activated
`downstream of many cell--surface receptors, including recep-
`tor tyrosine kinases, cytokine receptors and integrins [12].
`Well
`established as
`critical
`for
`the
`full activation of
`phospholipase-C g (PLC-g) and MAPK as well as calcium
`mobilization downstream of antigen receptors [12], TEC kin-
`ases were recently described in actin reorganization and cell
`polarization, as well as transcriptional regulation, cell survival
`and cellular transformation [12-14]. TEC family members share
`significant structural and sequence homology, including the
`presence of distinct proline-rich (PR) regions as well as
`N-terminal pleckstrin homology (PH) and TEC homology
`(TH) domains. The exceptions to this classification are Rlk,
`which contains PR regions but not TH or PH domains, and
`Bmx that does not contain PR regions [12]. The PH domain
`is not found in other cytoplasmic PTK and plays an essential
`
`role in the regulation and function of the BTK. The PH
`domain is the site of activation by phosphatidylinositol phos-
`phates and G-protein bg subunits as well as inhibition by
`PKC [15-20]. Multiple partners and signaling pathways have
`been implicated for BTK and other TEC family kinases.
`TEC family kinases play central and diverse modulatory roles
`in various cellular processes. They participate in signal trans-
`duction in response to virtually all types of extracellular
`stimuli, which are transmitted by growth factor receptors,
`cytokine receptors, G-protein receptors, antigen receptors
`and integrins and are regulated by non-receptor tyrosine kin-
`ases such as SRC, JAK, SYK and FAK family kinases. In turn,
`they regulate many major signaling pathways including those
`of PI3K, PLC-g and PKC [12,21-24]. These pathways play mul-
`tiple roles in growth, differentiation and apoptosis. Recently,
`a new role for this family of kinases in cytoskeletal reorganiza-
`tion and cell motility was discovered. The actin cytoskeleton
`plays an essential role in a variety of cellular processes includ-
`ing cell division, cell shape, motility and chemotaxis. BTK is
`known to colocalize with actin fibers on stimulation of mast
`cells by the high affinity IgE receptor in a PH domain-
`dependent manner [25]. The PH domain of BTK has also
`been shown to promote actin filament bundle formation
`in vitro [25]. These and other observations suggest the possibil-
`ity that on stimulation BTK kinase is able to translocate to the
`actin cytoskeleton where BTK and its downstream targets
`may work coordinately to reorganize the cytoskeleton in
`response to stimuli.
`Genetic evidence supports a critical role for BTK in multi-
`ple hematopoietic signaling pathways including the B-cell
`antigen receptor (BCR), several cytokine receptors and a
`potential novel role in heterotrimeric G-protein-associated
`receptor signaling [9,10,26-28]. In B-lineage lymphoid cells, as
`an essential component of the B-cell signalosome, BTK is
`intimately involved in multiple signal transduction pathways
`regulating survival, activation, proliferation, maturation and
`differentiation [9,10]. The recognition of an antigen by the
`BCR triggers a signal transduction cascade that culminates
`in activation of multiple genes controlling activation, prolifer-
`ation, differentiation and survival of B cells. As such, alter-
`ation of BCR signaling is crucial
`for
`the survival of
`lymphoma cells [29]. As compared to non-tumor cells, BTK-
`mediated signaling through the BCR was found to occur
`more swiftly with increased levels of sustained cellular signal-
`ing in B-follicular lymphoma cells [12]. Recent observations
`also suggest the involvement of BTK in signal transduction
`pathways affecting gene transcription [30,31]. BTK is essential
`for the BCR-mediated activation of the NF-kB/Rel family
`of transcription factors, which in turn regulates genes control-
`ling B-cell growth [32]. BTK has also been shown to regulate
`the nuclear localization and transcriptional activity of the
`ubiquitously expressed multifunctional transcription factor
`BAP-135/TFII-I [33-35]. BAP-135/TFII-I is capable of binding
`to several promoter elements, including initiator elements
`(e.g., VpreB, TdT and possibly RAG, CD5, Bcl-2 and
`
`1458
`
`Expert Opin. Ther. Patents (2010) 20(11)
`
`SAN EX 1005, Page 5
`
`

`

`A.
`
`B.
`
`N-lobe
`
`Uckun & Qazi
`
`Hinge
`
`Inhibitor
`
`C-lobe
`
`C.
`
`HN
`
`O
`
`O
`
`NH
`
`O
`
`Triphosphate and Mg site
`several charged residues with
`asp, lys and arg plus asn
`
`Adenine site
`
`a hydrophobic
`abd flat region
`
`Sugar site
`
`Figure 1. Structure-based design of selective BTK inhibitors.
`BTK: Bruton’s tyrosine kinase.
`
`Bcl-xL), which are tyrosine phosphorylated in B cells after
`engagement of the BCR [35,36]. BTK also mediates induction
`of immunoglobulin heavy-chain transcription in B cells indi-
`rectly through Bright/ARID3a/Dril1, a member of the ARID
`family of transcription factors [30]. Following activation by
`BTK, TFII-I interacts with Bright, thus inducing activity of
`the immunoglobulin reporter gene [30]. Further, a functional
`interaction was discovered between the transcription factor
`signal transducer and activator of transcription 5A (STAT5A)
`and BTK [37]. BTK is the first cytoplasmic non-JAK tyrosine
`kinase to be identified as a positive regulator of STAT5A in
`B cells. These findings point to a novel pathway through
`which B-cell-specific signals mediated by BTK might commu-
`nicate with target genes via STAT5A. Recent studies have fur-
`ther revealed a nucleocytoplasmic shuttling system for BTK
`that has implications regarding potential targets inside the
`nucleus, which may be critical
`in gene regulation during
`B-cell development and differentiation as well as apoptosis.
`
`3. BTK as an anti-apoptotic molecular target
`in cancer
`
`Apoptosis is a common mode of eukaryotic cell death that is
`triggered by an inducible cascade of biochemical events
`leading to activation of endonucleases that cleave the nuclear
`
`DNA into oligonucleosome length fragments [38,39]. Several
`of the biochemical events that contribute to apoptotic cell
`death as well as both positive and negative regulators of
`apoptosis have recently been identified [38-40]. Inadequate
`apoptosis may contribute to the development as well as
`chemotherapy resistance of human leukemias and lym-
`phomas [38-40]. Several studies have shown that most chemo-
`therapeutic agents exert their anticancer activity by inducing
`apoptosis [38-40]. Therefore, resistance to apoptosis may be
`a major
`factor
`limiting the effectiveness of anticancer
`therapy [38-40]. Because of the paramount importance of inef-
`ficient apoptotic killing of cancer cells, contemporary
`research efforts in modern oncology are to a significant extent
`aimed at achieving greater apoptotic cell death in cancers. In
`murine B cells, BTK acts as an anti-apoptotic protein
`upstream of Bcl-xl within the B-cell antigen receptor (but
`not the CD40 receptor) activation pathway. Biochemical
`and genetic evidence have established that BTK is an inhibi-
`tor of the Fas/APO-1 death inducing signaling complex in
`B-lineage lymphoid cells. BTK associates with the death
`receptor Fas and impairs its interaction with Fas-associated
`protein with death domain (FADD). BTK associates with
`Fas via its kinase and PH domains and prevents
`the
`Fas--FADD interaction, which is essential for the recruitment
`and activation of FLICE by Fas during the apoptotic
`
`Expert Opin. Ther. Patents (2010) 20(11)
`
`1459
`
`SAN EX 1005, Page 6
`
`

`

`Bruton’s tyrosine kinase as a molecular target in treatment
`
`signal [41]. The fate of leukemia/lymphoma cells may, there-
`fore, reside in the balance between the opposing proapop-
`totic effects of caspases activated by the death-inducing
`signaling complex and an upstream anti-apoptotic regulatory
`mechanism involving BTK and/or its substrates. Recent
`studies indicate that the anti-apoptotic function of BTK is
`required for pre-B-cell receptor-dependent survival signals
`(including activation of PLC-g1, autonomous Ca(2+) signal-
`ing, STAT5 phosphorylation and upregulation of BCLXL)
`that rescue BCR--ABL+ leukemia cells from apoptosis [42].
`BTK has emerged as an upstream activator of multiple
`anti-apoptotic signaling molecules and networks, including
`the STAT5 protein [37], PI3K/AKT/mammalian target of
`rapamycin (mTOR) pathway [43] and NF-kB [44,45]. Of the
`many BTK-linked signaling molecules
`and networks,
`STAT5 is an important regulator of survival
`[44-50] and
`proliferation [45,47,51-54] of B-cell precursor (BCP) at various
`stages of B-cell ontogeny. STAT5 knockout mice suffer
`from leucopenia/lymphopenia and an accelerated rate of lym-
`phohematopoietic cell apoptosis in the bone marrow [44].
`Conversely, constitutive activation of STAT5 is capable of
`causing leukemic transformation of
`lymphohematopoietic
`cells [46] and development of BCP leukemia in mice [47].
`Antisense depletion of STAT5 in malignant lymphoblasts
`was shown to decrease mRNA levels of NF-kB signaling
`pathway intermediates Traf2, Traf5 and Bcl10 and inhibit
`NF-kB activity leading to apoptosis [48]. In another study,
`STAT5 antisense oligonucleotides
`inhibited proliferation
`and triggered apoptosis
`in human leukemia cells
`[52].
`Dominant-negative forms of STAT5 induced massive apo-
`ptosis in BCP acute lymphoblastic leukemia (ALL) cells [50].
`Sonoyama et al. reported that dominant negative STAT5
`inhibits proliferation and enhances
`chemosensitivity of
`BCR-ABL+ BCP-ALL cells to dexamethasone [53]. Deactiva-
`tion of STAT5 by the tyrosine kinase inhibitor sorafenib has
`been shown to induce apoptosis
`in BCR-ABL positive
`BCP-ALL cells and constitutively active STAT5 is capable
`of protecting BCR-ABL positive
`leukemia
`cells
`from
`sorafenib-induced apoptosis [55]. Likewise, deactivation of
`STAT5 in BCR-ABL positive leukemia cells by the tyrosine
`kinase inhibitor dasatinib resulted in downregulation of
`STAT5 target genes, including BCL-xL and cyclin D, leading
`to inhibition of cell proliferation and induction of apopto-
`sis [56]. Notably, STAT5 is a direct substrate of BTK and is
`activated by BTK-mediated tyrosine phosphorylation of its
`Y694 residue [37]. BTK is required for pre-B-cell receptor-
`dependent
`survival
`signals
`in BCP-ALL cells,
`including
`STAT5 activation and STAT5-mediated upregulation of
`BCL-xL, which rescues BCR-ABL+ BCP-ALL cells from apo-
`ptosis. The BTK-linked NF-kB and PI3K/AKT survival path-
`ways are activated by chemotherapeutic agents and also
`contribute to drug resistance of BCP-ALL cells [57-59]. BTK
`the NF-kB pathway via its substrate PLC-g2.
`regulates
`mTOR is a serine--threonine kinase, which is activated by
`AKT and plays an important role in leukemic cell survival
`
`in BCP-ALL. Several functionally related genes intimately
`linked to the anti-apoptotic PI3K/AKT pathway are transcrip-
`tionally upregulated and differentially expressed in primary leu-
`kemic cells of chemotherapy-resistant BCP-ALL patients [59].
`Treatment of childhood BCP-ALL cells with an inhibitor of
`the PI3K or rapamycin stimulated apoptosis and enhanced che-
`motherapy sensitivity [60]. Most recently, it has been reported
`that the mTOR inhibitor RAD001/everolimus potentiated
`the in vitro anti-leukemic efficacy of vincristine against BCP-
`ALL cells and triggered both apoptosis and autophagy [61]. Fur-
`thermore,
`it also potentiated the effect of vincristine in a
`NOD/SCID mouse model of human BCP-ALL [61].
`from
`BTK is abundantly expressed in malignant cells
`patients with BCP-ALL, the most common form of cancer in
`children and adolescents, chronic lymphocytic leukemia
`(CLL), non-Hodgkin’s lymphoma [62-64] and acute myeloid
`leukemia (AML) [65]. Likewise, the TEC family member
`BMX tyrosine kinase, which is closely related to BTK and,
`therefore, subject to BTK inhibitors, is abundantly expressed
`in AML as well as CML [66,67]. Davis et al. recently reported
`evidence obtained using an RNA interference genetic screen
`that BTK plays a pivotal role in chronic active BCR signa-
`ling that is associated with constitutive NF-kB pathway activity
`and is required for the survival of diffuse large B-cell lymphoma
`(DLBCL) cells [68]. A meta-analysis of cancer-associated gene
`expression changes utilizing the Oncomine database revealed
`a marked enrichment of
`the most discriminating BTK-
`dependent anti-apoptotic gene targets in 17 comparisons for
`diagnostic classes of human leukemias and lymphomas
`obtained from eight studies (Table 1).
`Three of the diagnostic classes were represented in multiple
`studies: B-lineage ALL in two studies; CLL in five studies and
`DLBCL in five studies. We observed 51 significant compari-
`sons at the 5% significance level for 7 upregulated BTK tar-
`gets (True Discovery Rate = 87%). Message for BTK was
`upregulated in three diagnostic classes of B-cell malignancies
`whereby one study for B-lineage ALL showed a 1.78-fold
`increase in expression, two studies for CLL showed 3.3-
`and 1.99-fold increases
`in expression, and two studies
`for DLBCL showed 1.32- and 1.71-fold increases in expres-
`sion. Concordant increases in expression were observed for
`BTK and AKT1 in B-lineage ALL, CLL and DLBCL; BTK
`and PIK3AP1 in B-cell ALL, and two comparisons for CLL;
`and BTK and STAT5 in B-lineage ALL, CLL and DLBCL.
`Notably, in addition to BTK, five out of the seven BTK
`targets were upregulated in B-lineage ALL from the Andersson
`study. Five comparisons were represented by four BTK or
`BTK target genes that included four diagnostic B-cell malig-
`nant classes: centroblastic lymphoma, CLL, DLBCL and hairy
`cell leukemia (HCL). Three genes showed significant upregu-
`lation in eight comparisons (AKT1, BCL2L1 and CCND1).
`At least one of the NF-kB genes (RELA or NFKB2) showed
`increases in expression levels in 10 comparisons. Examination
`of the diagnostic classes in multiple studies demonstrated
`PIK3AP1 to be upregulated in three studies for CLL and
`
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`Uckun & Qazi
`
`Table 1. Meta-analysis of upregulated expression of BTK and its downstream effectors in B-lineage lymphoid
`malignancies.
`
`Oncomine Ref.
`
`Diagnosis
`
`Fold increases in expression levels
`
`BTK AKT1
`
`PIK3AP1 BCL2L1 CCND1 NF-kB RELA STAT5
`
`BTK targets
`
`B-lineage ALL
`Andersson leukemia
`B-lineage ALL
`Maia leukemia
`B-lineage ALL/Burkitt’s lymphoma
`Basso lymphoma
`Centroblastic lymphoma
`Basso lymphoma
`CLL
`Alizadeh lymphoma
`CLL
`Basso lymphoma
`CLL
`Haslinger leukemia
`CLL
`Rosenwald lymphoma
`Rosenwald multi-cancer CLL
`Alizadeh lymphoma
`DLBCL
`Basso lymphoma
`DLBCL
`Rosenwald lymphoma
`DLBCL
`Rosenwald multi-cancer DLBCL
`Storz lymphoma
`DLBCL
`Basso lymphoma
`HCL
`Basso lymphoma
`Mantle cell lymphoma
`Storz lymphoma
`Marginal zone B-cell lymphoma
`
`1.78
`
`1.34
`
`1.40
`
`1.48
`
`1.92
`
`3.30
`1.99
`
`1.32
`1.71
`
`2.97
`1.55
`
`2.46
`
`1.39
`
`1.46
`1.27
`1.43
`
`2.69
`
`1.25
`1.29
`
`1.79
`
`1.49
`1.38
`
`1.91
`1.61
`
`1.45
`
`1.52
`
`2.95
`
`1.57
`
`1.58
`1.40
`1.52
`1.51
`
`1.43
`1.37
`
`1.96
`1.96
`
`1.99
`
`10.04
`109.9
`
`1.34
`
`1.41
`
`1.31
`
`1.49
`1.71
`
`2.14
`1.50
`
`1.84
`1.18
`
`1.99
`1.69
`
`1.29
`
`ALL: Acute lymphoblastic leukemia; BTK: Bruton’s tyrosine kinase; CLL: Chronic lymphocytic leukemia; DLBCL: Diffuse large B-cell lymphoma; HCL: Hairy
`cell leukemia.
`
`four genes (AKT1, BCL2L1, CCND1 and NF-kB) to be
`upregulated in three studies for DLBCL. The greatest fold dif-
`ferences were observed with CCND1 for mantle cell lym-
`phoma (109.9-fold increase) and HCL (10-fold increase).
`Taken together,
`these
`studies highlight
`transcriptional
`level activation of BTK and prominent BTK-dependent
`anti-apoptotic genes in B-lineage leukemias and lymphomas.
`In accordance with the anti-apoptotic function of BTK,
`inhibition of BTK with a small molecule inhibitor disrupted
`BTK-Fas association and rendered resistant leukemic cells
`sensitive to Fas-mediated apoptosis [41]. Furthermore, inhi-
`bition of BTK in B-lineage leukemia cells enhanced their
`sensitivity to vincristine-induced apoptosis both in vitro
`and in vivo [8,41,69]. Therefore, BTK inhibitors show poten-
`tial as anti-leukemic agents with apoptosis-promoting and
`chemosensitizing properties. BTK inhibitors may potentiate
`the anti-leukemic effect of the individual components of
`induction chemotherapy as well as post-induction intensifi-
`cation and maintenance chemotherapy by inhibiting the
`BTK-dependent anti-apoptotic chemotherapy resistance of
`leukemic cells. Therefore, BTK inhibitors maybe clinically
`useful when used as part of remission-induction therapy,
`intensification (or
`consolidation)
`therapy
`as well
`as
`maintenance therapy to eliminate residual leukemia.
`
`4. BTK as a molecular target in GVHD
`
`Bone marrow transplantation (BMT) has become one of the
`standard treatment modalities offered to high risk leukemia
`
`patients [70-73]. Very intensive ‘supralethal’ myeloablative che-
`motherapy or radiochemotherapy regimens can be applied in
`the context of BMT with a curative intent to overcome the
`drug resistance of residual leukemia cells of certain leukemia
`patients who are unlikely to be cured by standard chemother-
`apy [71-73]. In addition, leukemia patients undergoing allogeneic
`BMT may benefit from the graft-versus-leukemia effect of the
`marrow allograft. Graft-versus-host disease (GVHD), a donor
`T-cell initiated highly complex pathologic condition that fre-
`quently follows allogeneic BMT, especially in the context of a
`major-HLA (human leukocyte antigen) disparity, is associa-
`ted with significant morbidity and mortality [71-77]. Severe
`GVHD remains a major obstacle to a more successful outcome
`of allogeneic BMT using HLA-matched unrelated donors as
`well as partially HLA-mismatched related donors [72,73]. There-
`fore, GVHD prophylaxis aimed at reducing the risk of severe
`GVHD is an integral component of all BMT programs [71-73].
`Recent studies in a mouse BMT model demonstrated that
`the addition of a BTK inhibitor to the GVHD prophylaxis
`regimens
`significantly improves
`the survival outcome of
`allogeneic BMT [78]. Notably, > 70% of BMT recipients
`treated with a BTK inhibitor-containing combination regi-
`men remained alive throughout
`the 80-day observation
`period. Therefore, incorporation of BTK inhibitors in clinical
`GVHD prophylaxis regimens may improve the outcome by
`reducing the incidence of severe GVHD. We propose that
`the antileukemic activity of BTK inhibitors may enhance their
`ability to attenuate the severity of GVHD without increasing
`the risk of relapse post-BMT in clinical settings.
`
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`Bruton’s tyrosine kinase as a molecular target in treatment
`
`5. BTK as a molecular target in
`thromboembolism
`
`Cancer, especially at advanced stages and time of disease pro-
`gression, is associated with hypercoagulability leading to vas-
`cular events and thromboembolic complications which are a
`significant cause of morbidity and mortality [79]. Thrombo-
`embolic events may be triggered by tumor progression,
`inflammatory host responses to the tumor, vascular damage
`and circulatory changes caused by extrinsic tumor pressure
`or venous or direct blood vessel trauma [79,80]. The develop-
`ment of a platelet-rich thrombus on damaged endothelium
`or atherosclerotic plaques can severely impair the blood flow
`to vital organs, including the brain, heart, lungs and kid-
`neys [80,81]. The contribution of platelets to the pathogenesis
`of potentially fatal ischemic and/or thromboembolic events,
`including stroke, myocardial infarct and pulmonary embo-
`lism, is well documented [80,81]. Therefore, the discovery of
`effective modulators of platelet function that can prevent
`thrombus formation is the focus of intensified efforts in trans-
`lational hematology and cardiovascular biology research. Such
`agents may be potentially useful in cancer patients, includ-
`ing leukemia patients, especially those being treated with
`L-asparaginase, who are at risk of suffering from thromboem-
`bolic complications because of their hypercoaguable state or
`the procoagulant effects of chemotherapy.
`Platelet binding via the surface a2b1 integrin and glycopro-
`tein GPVI to the extracellular matrix protein collagen from
`exposed subendothelium at sites of vascular injury initiates a
`tyrosine kinase-dependent signal transduction cascade leading
`to platelet activation, degranulation, aggregation and forma-
`tion of a hemostatic thrombus [82-85]. Platelet binding to col-
`lagen contributes to thrombus formation regardless of the
`nature of the initiating or propagating factors for thrombo-
`genesis [82-85]. Therefore, new age