Akinleye et al. Journal of Hematology & Oncology 2013, 6:59
`http://www.jhoonline.org/content/6/1/59
`
`JOURNAL OF HEMATOLOGY
`& ONCOLOGY
`
`R E V I E W
`Open Access
`Ibrutinib and novel BTK inhibitors in clinical
`development
`Akintunde Akinleye1, Yamei Chen1,2, Nikhil Mukhi1, Yongping Song3 and Delong Liu1,3*
`
`Abstract
`
`Small molecule inhibitors targeting dysregulated pathways (RAS/RAF/MEK, PI3K/AKT/mTOR, JAK/STAT) have
`significantly improved clinical outcomes in cancer patients. Recently Bruton’s tyrosine kinase (BTK), a crucial terminal
`kinase enzyme in the B-cell antigen receptor (BCR) signaling pathway, has emerged as an attractive target for
`therapeutic intervention in human malignancies and autoimmune disorders. Ibrutinib, a novel first-in-human
`BTK-inhibitor, has demonstrated clinical effectiveness and tolerability in early clinical trials and has progressed
`into phase III trials. However, additional research is necessary to identify the optimal dosing schedule, as well as
`patients most likely to benefit from BTK inhibition. This review summarizes preclinical and clinical development
`of ibrutinib and other novel BTK inhibitors (GDC-0834, CGI-560, CGI-1746, HM-71224, CC-292, and ONO-4059,
`CNX-774, LFM-A13) in the treatment of B-cell malignancies and autoimmune disorders.
`
`Introduction
`Identifying novel mediators that regulate the growth and
`death of cancer cells has facilitated the development of
`more effective anti-cancer agents that have revolutionized
`treatment options and clinical outcomes in cancer pa-
`tients [1-4]. For instance, rituximab, a first-in-class chimeric
`monoclonal antibody (MoAb) targeting CD 20 molecule,
`has had clear impact on response rates and survival out-
`comes, and has become a standard component of treatment
`regimens for many patients with B-cell non-Hodgkin’s
`lymphomas (NHLs) [5-7]. MoAbs targeting CD 19 molecule
`are also rapidly moving through clinical trials [8]. In recent
`times, Bruton’s tyrosine kinase (BTK), a crucial terminal
`kinase enzyme in the B-cell antigen receptor (BCR) signaling
`pathway has emerged as a novel target [9]. This downstream
`signal transduction protein is a critical effector molecule that
`governs normal B-cell development, differentiation and func-
`tioning, and has also been implicated in initiation, survival
`and progression of mature B-cell
`lymphoproliferative
`disorders [10].
`Ibrutinib, a novel BTK-targeting inhibitor, has shown
`significant activities across a variety of B-cell neoplastic
`
`* Correspondence: delong_liu@nymc.edu
`1Division of Hematology/Oncology, Department of Medicine, New York
`Medical College, Valhalla, New York 10595, USA
`3Institute of Hematology, Zhengzhou University Affiliated Tumor Hospital,
`Zhengzhou, China
`Full list of author information is available at the end of the article
`
`disorders and autoimmune diseases in preclinical models
`and clinical trials [11]. However, additional research is ne-
`cessary to identify the optimal dosing schedule, as well as
`patients most likely to benefit from BTK inhibition. This
`review provides a general overview of three main topics:
`1) BTK signaling pathway in B-cell lymphopoiesis with
`emphasis on its role in the pathogenetic mechanisms that
`underlie B-cell lymphoproliferative disorders; 2) Novel
`BTK inhibitors in preclinical and clinical development.
`and 3) Preclinical models and clinical experiences with
`ibrutinib and other BTK inhibitors in the treatment of
`various B-cell disorders and autoimmune disorders.
`
`BTK signaling pathway, B-cell lymphopoiesis, and
`tumorigenesis
`BTK, also known as agammaglobulinemia tyrosine kinase
`(ATK) or B-cell progenitor kinase (BPK), is a non-receptor
`tyrosine kinase that was initially identified as the defective
`protein in human X-linked agammaglobulinemia (XLA)
`[12,13]. The protein is predominantly expressed in B-
`lymphocytes at various stages of development (except in
`terminally differentiated plasma cells), and less commonly
`in myeloid and erythroid progenitor cells [14]. It is encoded
`by the XLA gene that maps to a 37 kb DNA fragment on
`chromosome Xq22 [15,16]. BTK is a member of the Tec
`family of protein tyrosine kinases. The Tec family has five
`members and is the second largest family of cytoplasmic
`tyrosine kinases. BTK has domains of pleckstrin homology
`
`© 2013 Akinleye et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
`Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
`reproduction in any medium, provided the original work is properly cited.
`
`SANDOZ INC.
`
`IPR2023-00478
`
`Ex. 1018, p. 1 of 9
`
`

`

`Akinleye et al. Journal of Hematology & Oncology 2013, 6:59
`http://www.jhoonline.org/content/6/1/59
`
`Page 2 of 9
`
`(PH), Tec homology (TH), Src homology 3 (SH3), Src
`homology 2 (SH2), and tyrosine kinase or Src homology 1
`(TK or SH1) (Figure 1) [17]. The PH domain contains
`the binding site for transcription factor BAP-135/TFII-I
`[18], harbors the inhibitory segment for downregulators
`such as PIN 1, IBTK (inhibitor of BTK) [19], and also
`mediates BTK’s interaction with second messenger phos-
`phatidylinositol 3,4,5-trisphosphates (PIP3) [20]. Adjacent
`to the PH domain is a segment of 80 amino acid residues
`denoted as the TH domain. The TH domain houses
`conserved regions designated as BTK motif (zinc cofactor
`binding site) and proline-rich stretch [21], and serves as a
`major determinant binding site for protein kinase C-beta
`(PKC-β) [22]. Initial activation (trans-phosphorylation)
`of BTK takes place in the activation loop located in the
`SH1/TK domain; however further activation occurs within
`the SH3 and SH2 domains, which contains major auto-
`phosphorylation sites [23,24]. These Src homologous
`domains also contain the nuclear localization signals (NLS)
`and nuclear export sequence (NES) required for nucleocyto-
`plasmic shuttling of BTK [25]. In addition to the activa-
`tion loop, the ATP binding site, the catalytic apparatus,
`and the allosteric inhibitory segments are also situated
`in the SH1/TK domain [26].
`BTK functions downstream of multiple receptors in-
`cluding growth factors, B-cell antigen, chemokine, and
`innate immune receptors, and thereby initiates a diverse
`range of cellular processes, such as cell proliferation,
`survival, differentiation, motility, angiogenesis, cytokine
`production, and antigen presentation [27-30]. In steady-
`state conditions, BTK is predominantly cytosolic, un-
`phosphorylated and catalytically inactive [20]. BTK acti-
`vation is a complex process and a critical step in this
`process requires translocation of BTK to the plasma
`membrane [20].
`
`Upon engagement by their corresponding ligands, acti-
`vated receptors recruit and phosphorylate intracellular
`signal transducer enzyme, phosphatidylinositol 3-kinase
`(PI3K), which then acts on membrane-bound phos-
`phatidylinositol 4,5-bisphosphate (PIP2) to generate sec-
`ond messenger phosphatidylinositol 3,4,5-trisphosphates
`(PIP3) [20]. PIP3 binds to BTK’s PH domain and recruits
`BTK to the plasma membrane, where BTK is initially
`trans-phosphorylated at Tyr-551residue by Syk and Lyn
`kinases [31]. BTK then undergoes autophosphorylation
`reaction at Tyr-223 residue to become physiologically
`active [24]. Activated BTK can interact with adapter
`protein BLNK/SLP65 through its SH2 domain. The com-
`plex can then activate phospholipase C (PLC)-γ2 [32],
`triggering a cascade of events that culminates in sustained
`intracellular calcium influx and indirect activation of
`downstream transcriptional signaling such as MEK/ERK, p38
`MAPK, and JNK/SAPK pathways (Figure 2) [27,28,33-35].
`Other downstream substrates of BTK include transcrip-
`tion factors BAP-135/TFII-I, NFκB, ARID3A, STAT3 and
`NFAT, where BTK plays a critical role in direct transcrip-
`tion regulation and the expression of hundreds of genes
`[29,31,34,36]. Under certain physiological conditions, BTK
`can translocate to the nucleus and activate the transcrip-
`tion of specific target genes [25], but BTK itself does not
`bind directly to the DNA.
`PKC-β can directly phosphorylate BTK’s TH domain
`at Ser-180, resulting in shuttling of BTK back to the
`cytoplasmic compartment [22]. Interactions with PIN1,
`SH3BP5, CAV1 and IBTK also lead to dramatic down-
`regulation of the kinase activity of BTK [19,37-39].
`BTK plays indispensable roles in B-cell lymphopoiesis.
`It orchestrates orderly development and differentiation
`of immature B-cells to mature forms through activation
`of positive cell cycle regulators and differentiation factors
`
`Figure 1 BTK structure. BTK belongs to the Tec family of protein tyrosine kinases and is composed of the PH (pleckstrin homology), TH (Tec homology),
`SH3 (Src homology 3) SH2 (Src homology 2), and SH 1/TK (Src homology1/Tyrosine kinase) domains. Binding sites for BTK substrates, inhibitors, and
`upstream molecules are shown in the diagram.
`
`SANDOZ INC.
`
`IPR2023-00478
`
`Ex. 1018, p. 2 of 9
`
`

`

`Akinleye et al. Journal of Hematology & Oncology 2013, 6:59
`http://www.jhoonline.org/content/6/1/59
`
`Page 3 of 9
`
`Figure 2 BTK signaling pathway. BTK translocates to the plasma membrane by interacting with PIP3 to become membrane-bound where it
`undergoes sequential activation through trans-phosphorylation by Lyn and Syk kinases, followed by autophosphorylation. The downstream
`substrates of activated BTK and their associated signaling cascades are indicated.
`
`[17,28], and also controls proliferation and survival of
`B-cells by regulating expression of pro- and anti-apoptotic
`proteins [40-42].
`Aberrant activation of the BTK-dependent pathways has
`been implicated in maintaining malignant phenotype in a
`wide variety of malignancies. Basal growth, survival, and
`cancer progression in mature B-cell lymphoproliferative
`disorders appear to be promoted by dysregulated BTK
`activity [10,43,44]. Constitutive BTK activation repre-
`sents an absolute prerequisite for CLL development and
`enhances leukemogenesis in mouse models of CLL [45].
`In addition, altered BCR-BTK signaling promotes cell
`survival
`in the activated B-cell-like (ABC) subtype of
`
`DLBCL [46]. Somatic gain-of-function mutations in BTK
`have also been identified in colorectal carcinoma [47],
`acute lymphoblastic leukemia (ALL) [48], and chronic
`myeloid leukemia (CML) [49].
`
`BTK inhibitors (BTKi) in clinical trials and
`preclinical development
`Small molecules with BTK-inhibitory property have
`emerged as promising therapeutic agents for the treat-
`ment of hematological malignancies and autoimmune
`disorders [50-52]. As such, a number of compounds,
`such as ibrutinib, GDC-0834, HM-71224, CC-292, and
`
`SANDOZ INC.
`
`IPR2023-00478
`
`Ex. 1018, p. 3 of 9
`
`

`

`Akinleye et al. Journal of Hematology & Oncology 2013, 6:59
`http://www.jhoonline.org/content/6/1/59
`
`Page 4 of 9
`
`ONO-4059, have progressed through advanced preclinical
`development to clinical trials [http://clinicaltrials.gov].
`
`Ibrutinib
`Preclinical studies of ibrutinib
`Ibrutinib (formerly PCI-32765) is an orally bioavailable,
`first-in-class, highly potent small molecule inhibitor
`with subnanomolar activity (IC50, 0.5 nM) against BTK
`(Table 1) [11]. It selectively binds to Cys-481 residue in
`the allosteric inhibitory segment of BTK (TK/SH1 domain),
`and irreversibly blocks its enzymatic activity [53]. The
`compound also abrogates the full activation of BTK by
`inhibiting its autophosphorylation at Tyr-223 [11]. In-
`vitro studies showed that ibrutinib induces dose- and
`time-dependent cytotoxicity in CLL tumor cell lines via
`activation of caspase-3 dependent apoptotic pathway [9].
`Ibrutinib also inhibits DNA replication [54], suppresses
`TLR signaling-mediated proliferation [9], and blocks
`pro-survival pathways in CLL cells by downregulating
`CCL3 and CCL4 expression [54]. More so, the com-
`pound antagonizes BTK-dependent chemotaxis to CXCL12
`and CXCL13 [55]. Ibrutinib interferes with proliferation
`and survival in B-ALL cell lines including Ph+/BCR-ABL1
`positive cells [56]. In a xenografted TCL1 mouse model
`of CLL, ibrutinib dosed at 25 mg/kg/day delayed disease
`progression [54]. In-vivo studies by Honigberg et al.
`using MRL-Fas (lpr) lupus mouse models demonstrated
`that ibrutinib-induced BTK inhibition is associated with
`reduced autoantibody production and suppression of
`kidney disease development [11].
`
`Clinical trials of ibrutinib
`Ibrutinib is highly efficacious and safe, and has now
`entered phase III clinical trials for a variety of B-cell
`neoplasms. In an initial, multi-institutional phase I dose-
`escalating study, two dosing schedules of ibrutinib was
`tested in patients with relapsed or refractory FL, SLL/CLL,
`
`MCL, MZL, DLBCL, and WM who had failed at least one
`previous therapy [57]. Fifty-six patients received oral
`ibrutinib at doses of 1.25, 2.5, 5, 8.3, or 12.5 mg/kg daily
`on a 28 days on, 7 days off schedule (35-day cycle), or
`continuous daily dosing of 8.3 mg/kg or 560 mg until
`disease progression (PD) or unacceptable toxicity. After
`a median of 5 cycles of treatment, only two dose-
`limiting toxicities (DLTs) occurred and ibrutinib was
`found to be safe and well tolerated. The most common
`adverse effects were grade 1 or 2 non-hematologic
`toxicities, which included rash, nausea, fatigue, diarrhea,
`muscle spasms/myalgia and arthalgia. Hematologic toxic-
`ities were less common, and included grade 3 to 4 neu-
`tropenia (12.5%), thrombocytopenia (7.2%), and anemia
`(7.1%). In CLL patients, ibrutinib treatment is character-
`istically associated with rapid resolution of enlarged lymph
`nodes along with a surge in peripheral blood lymphocytosis.
`Of 50 patients evaluated for response, an overall response
`rate (ORR) of 60% was achieved across all histological types
`with the best efficacy demonstrated in patients with MCL
`(78%) and SLL/CLL (79%). The responses lasted for at least
`10 months. Notably, a median progression free survival
`(PFS) of 13.6 months was also achieved [57]. Though
`both intermittent and continuous dosing schedules dem-
`onstrated similar efficacy and toxicity profiles, the study
`favored continuous dosing for phase II studies due to
`possibility of reversed biologic activity with intermittent
`therapy.
`Given the high efficacy of ibrutinib in the precedent
`phase I study, a larger study was done to investigate the
`activity of single-agent ibrutinib in 111 heavily-pretreated
`patients with relapsed or refractory MCL [58]. Patients
`received a daily dose of 560 mg orally in a continuous
`28-day cycles until disease progression or unacceptable
`toxicities. After a median follow-up of 15.3 months, the
`ORR was 68% (21% CR, 47% PR) with median response
`duration of 17.5 months, and was independent of
`
`Table 1 BTK Inhibitors in preclinical and clinical development
`BTK inhibitor
`Stage of development
`Ibrutinib
`Phase II/III
`
`Disease(s)
`CLL/SLL, MCL, WM, ABC-DLBCL, MM
`
`GDC-0834
`
`RN-486
`
`CGI-560
`
`CGI-1746
`
`HM-71224
`
`CC-292
`
`ONO-4059
`
`CNX-774
`
`LFM-A13
`
`NR not reported.
`
`Phase I
`
`Preclinical
`
`Preclinical
`
`Preclinical
`
`Phase I
`
`Phase I
`
`Phase I
`
`Preclinical
`
`Preclinical
`
`Rheumatoid Arthritis
`
`Rheumatoid Arthritis, SLE
`
`NR
`
`Rheumatoid Arthritis
`
`Rheumatoid Arthritis
`
`CLL/B-NHL
`
`CLL
`
`Autoimmune Diseases, B-cell NHL
`
`B-cell NHL
`
`IC50
`0.5 nM
`
`5.9 nM
`
`4.0 nM
`
`400 nM
`
`1.9 nM
`
`NR
`
`< 0.5 nM
`
`2.2 nM
`
`< 1 nM
`17.2 μM
`
`Reference
`[54,57,58,60]
`
`[70,71]
`
`[72,73]
`
`[74]
`
`[74]
`
`[75]
`
`[76-78]
`
`[79]
`
`[80]
`
`[81-83]
`
`SANDOZ INC.
`
`IPR2023-00478
`
`Ex. 1018, p. 4 of 9
`
`

`

`Akinleye et al. Journal of Hematology & Oncology 2013, 6:59
`http://www.jhoonline.org/content/6/1/59
`
`Page 5 of 9
`
`patients’ baseline characteristics or risk factors. Though
`the median OS was not reached, the median PFS was
`13.9 months. Based on these collective efficacy data,
`ibrutinib was granted a ‘breakthrough therapy’ designa-
`tion by the FDA in February 2013 for patients with
`relapsed/refractory MCL, and a phase III registration trial
`(RAY) of ibrutinib monotherapy versus temsirolimus has
`been initiated in the same patient population.
`Long-term tolerability and sustained antitumor activity
`of ibrutinib in heavily pretreated patients with refractory/
`relapsed FL have also been reported. Kunkel and col-
`leagues showed that ibrutinib was well-tolerated and
`active, with an ORR was 55% (3 CR) and median PFS
`was 13.4 months [59]. Most common treatment-related
`side effects were dry mouth, constipation and diarrhea.
`Encouraging results from the phase I study in CLL pa-
`tients prompted a phase Ib/II trial, where patients with
`relapsed/refractory CLL/SLL (n=85), predominantly with
`high-risk disease, received oral ibrutinib at either 420 mg
`or 840 mg daily until disease progression or unacceptable
`toxicity [60]. Tolerability profile was acceptable as most
`adverse events were grade 1 or 2 diarrhea, fatigue, and
`URI that resolved spontaneously. Higher drug discon-
`tinuation rate occurred in the 840 mg cohort compared
`with the 420 mg cohort (12% versus 4%). The ORR was
`71% in both cohorts, and not dependent on clinical and
`genomic risk factors (such as 17p deletion) present
`before treatment. The characteristic drug-induced re-
`distribution lymphocytosis that accompanies lymph node
`reduction was observed generally by day 7, peaked at
`median of 4 weeks of treatment, and then slowly declined.
`The responses were durable with the estimated 26-month
`PFS and OS rates being 75% and 83% respectively. Of note,
`this study initially included thirty-one treatment-naïve CLL
`patients older than 65 years, where ibrutinib was investi-
`gated as an upfront therapy. After a median follow-up of
`16.6 months, the overall response rate was 71% (CR 10%)
`suggesting that ibrutinib could be a reasonable choice for
`newly diagnosed elderly patients with CLL [61,62].
`Patients’ enrollment is underway for two phase III
`registration trials of single-agent ibrutinib in CLL/SLL
`patients to further demonstrate its impact on clinical
`outcomes. In RESONATE 1, ibrutinib is being compared
`with ofatumumab in patients with relapsed/refractory CLL/
`SLL, whereas RESONATE 2 is to investigate ibrutinib as
`frontline therapy for newly diagnosed elderly patients
`with CLL/SLL in comparison with chlorambucil. In-
`terim analyses from these trials are expected during the
`1st quarter 2014.
`Updated interim results from an ongoing open label
`phase II trial showed that ibrutinib is active in patients
`with activated B cell-like (ABC) subtype of DLBCL har-
`boring both CD79B and MYD88 L265P mutations [63].
`Heavily pretreated patients (n=70) with relapsed/refractory
`
`DLBCL received oral ibrutinib 560 mg daily until disease
`progression or onset of unacceptable toxicities. The ORR
`was significantly greater in patients with the ABC subtype
`compared to those with the GCB subtype (41% versus 5%,
`p=0.007), suggesting preferential antitumor activity in ABC
`DLBCL. The median OS was 9.7 months for the ABC
`subtype, compared to 3.35 months for the GCB sub-
`type. Similarly, ibrutinib has potential antitumor activ-
`ities in multiple myeloma (MM), targeting both tumor
`cells and their supporting microenvironment. Vij and
`colleagues reported early reductions in plasma levels
`of growth factors (e.g. VEGF, EGF, and FGF), cytokines
`(e.g. TNFα), chemokines (CCL3, CCL4, Groα), and markers
`of bone turnover (e.g. sclerostin, RANKL) in patients with
`relapsed/refractory MM treated with ibrutinib 420 mg
`once daily [64].
`
`Clinical trials of ibrutinib in combination regimens
`The promising results of single agent ibrutinib have led
`investigators to explore its synergistic efficacy in com-
`bination with established chemoimmunotherapy regimens
`with the goal of enhancing and achieving durable re-
`sponses. Treatment with ibrutinib plus ACY1215, a
`selective histone deacetylase 6 (HDAC6) inhibitor, pro-
`duced a direct synergistic antitumor effect in MCL tumor
`cell lines accompanied by a 3-fold increase in induction of
`apoptosis [65]. One of the first clinical studies addressing
`this purpose was a phase II study that showed ibrutinib
`plus rituximab (IR) was profoundly effective (ORR=85%),
`and shortened the duration of re-distribution lymphocyto-
`sis in CLL patients with high-risk features [66]. Adding
`ibrutinib to BR (bendamustine and rituximab) appear to
`produce a better clinical response (ORR=93%) than IR in
`relapsed/refractory CLL patients [67]. In a recent report
`of another ongoing phase Ib/II study, administration of
`ibrutinib in combination with ofatumumab demonstrated
`potent anti-leukemic activity and tolerable toxicity profile
`in heavily-pretreated patients with relapsed/refractory
`CLL/SLL [68]. Blum et al. also demonstrated excellent
`response rates in MCL patients treated with a combin-
`ation of
`ibrutinib plus rituximab and bendamustine
`[69]. In light of these encouraging results, two phase III
`trials are currently accruing participants to investigate
`the combination of ibrutinib plus bendamustine and ri-
`tuximab versus placebo plus bendamustine and rituximab
`in subjects with newly diagnosed MCL (SHINE), as well
`as in patients with refractory/relapsed CLL (HELIOS).
`Additional preclinical experiments and clinical trials are
`currently underway to further explore this strategy in
`other B-cell disorders [NCT01829568, NCT01569750,
`NCT01479842].
`Given the current data, ibrutinib appears to be one of
`the most active single agents for CLL/SLL and MCL.
`
`SANDOZ INC.
`
`IPR2023-00478
`
`Ex. 1018, p. 5 of 9
`
`

`

`Akinleye et al. Journal of Hematology & Oncology 2013, 6:59
`http://www.jhoonline.org/content/6/1/59
`
`Page 6 of 9
`
`GDC-0834
`GDC-0834 is a potent, highly selective, reversible BTK
`inhibitor with nanomolar activity in enzyme kinetics
`studies. A carboxamide derivative, GDC-0834 is being
`developed as a potential therapeutic agent for rheumatoid
`arthritis (RA) [70]. The compound demonstrates effective
`activity against BCR- and CD40-dependent B-cell prolifera-
`tion and activation, and potently inhibits immune complex-
`mediated inflammatory cytokine elaboration in monocytes.
`In collagen-induced arthritis (CIA) rat models, treatment
`with oral GDC-0834 dosed at 30-100 mg/kg demonstrated
`robust anti-arthritis effect characterized by significant dose-
`dependent reduction in ankle swelling, and accompanied
`by potent inhibition of autophosphorylation of BTK [70].
`Pharmacokinetics (PK) results of a recent phase I study of
`GDC-0834 in healthy volunteers showed that the drug is
`heavily metabolized by the liver to an inactive metabolite
`via amide hydrolysis [71]. GDC-0834 is undergoing further
`clinical development to assess its safety and tolerability in
`patients with inflammatory arthritis.
`
`RN-486
`A potent and competitive small molecule with reversible
`BTK-inhibitory property, RN-486 demonstrates sub-
`nanomolar and highly specific activity against purified
`BTK in enzymatic assays. It blocks BCR-mediated CD69
`expression in B-cells in a dose-dependent manner. Pre-
`clinical studies also showed that RN-486 efficiently in-
`hibits FcR-mediated TNF-α production in monocytes,
`and abrogates FcεR-mediated mast cell degranulation [72].
`The anti-rheumatic potential of RN-486 has been investi-
`gated in preclinical studies. In two murine models of RA,
`the compound demonstrates potent anti-inflammatory
`and disease-modifying effects characterized by reduction
`in pannus formation, cartilage damage and bone resorption
`[72]. It also abrogates type I and type III hypersensitivity
`responses in rats. RN-486 suppresses IgG anti-dsDNA
`secretion, blocks CD69 expression in response to BCR
`crosslinking, and completely inhibits progression of glom-
`erular nephritis in systemic lupus erythematosus (SLE)
`prone NZB/W mouse models [73].
`
`CGI-560
`is a highly selective
`CGI-560, a benzamide derivative,
`(>10 fold) but modestly potent small molecule inhibitor of
`BTK with an IC50 of 400 nM in enzymology assays [74].
`Optimization of CGI-560 property by medicinal chemistry
`led to the discovery of another benzamide analogue (CGI-
`1746) with exquisite potency and unique BTK-inhibitory
`activity [74].
`
`CGI-1746
`An exquisitely selective and ATP-competitive small
`molecule inhibitor with unique BTK-inhibitory property,
`
`CGI-1746 potently inhibits both auto- and trans-
`phosphorylation of BTK. It binds and occupies an SH3
`binding pocket within the un-phosphorylated BTK and
`stabilizes it in this inactive enzyme conformation state
`[74]. In cellular assays, the compound blocks BCR-mediated
`B-cell proliferation and suppresses FcγRIII-induced TNFα,
`IL-1β and IL-6 production in macrophages. CGI-1746
`demonstrated robust anti-arthritic activity in experimen-
`tal mouse models evident by diminished cytokine and
`autoantibody levels in the joints [74].
`
`HM-71224
`HM-71224 is a novel, oral, small molecule BTK inhibitor
`that is being developed by Hanmi pharmaceuticals [75].
`The compound has progressed into phase I clinical testing,
`and its PD, PK, safety, and tolerability are being assessed
`in healthy volunteers in Korea and the Netherlands
`[NCT01765478].
`
`CC-292
`CC-292 (formerly AVL-292) is an orally bioavailable acryl-
`amide derivative with potent, irreversible anti-BTK activity
`(IC50 <0.5 nM) in biochemical kinase assays. The small
`molecule inhibitor abolishes BCR signaling in Ramos
`human Burkitt's lymphoma cell line by covalently bind-
`ing to BTK, and selectively inhibits its autophosphorylation
`as well as activation of PLCγ2 and other downstream sub-
`strates of BTK [76]. When dosed orally five times a week
`for 6 weeks, CC-292 decreased tumor burden in pre-
`clinical xenografts MM mouse models of human
`Luc-GFP+-MM.1S myeloma cell line [77]. In established
`CIA mouse models, treatment with CC-292 dosed at 3,
`10 and 30 mg/kg produced dose-dependent resolution
`of clinical signs and histopathologic features of inflam-
`matory joint disease including reduction in joint swell-
`ings and redness, and regression of pannus formation
`[76]. Clinical progress has been seen with CC-292. In
`normal healthy volunteers who received 2 mg/kg CC-292,
`PK analysis showed that the compound was rapidly
`absorbed, achieving peak plasma concentrations within
`30–120 minutes, and demonstrating a median terminal
`elimination half-life of 1.9 hours. Analysis of BTK activity
`in same study subjects indicated that the drug remained
`active for a prolonged duration after its plasma levels had
`declined to undetectable levels [76]. Given these data, CC-
`292 was advanced to phase Ib clinical testing in patients
`with B-cell disorders. Updated results from a dose-finding
`study of CC-292 in patients (n=86) with relapsed or re-
`fractory CLL and B-NHL revealed that the agent was
`generally well-tolerated at doses ranging from 125-1000
`mg daily, and at 375 and 500 mg twice daily [78]. The
`most common treatment-emergent adverse effects were
`diarrhea, fatigue, headaches and muscle spasms. Three
`DLTs including thrombocytopenia, pneumonitis, and altered
`
`SANDOZ INC.
`
`IPR2023-00478
`
`Ex. 1018, p. 6 of 9
`
`

`

`Akinleye et al. Journal of Hematology & Oncology 2013, 6:59
`http://www.jhoonline.org/content/6/1/59
`
`Page 7 of 9
`
`mental status were reported. Of 50 CLL patients evaluated
`for response, seventeen (34%) achieved PR. Multiple on-
`going phase I studies are expected to provide additional
`safety results on CC-292 as a single agent or combin-
`ation with other agents in patients with a wide variety
`of B-cell lymphoproliferative disorders [NCT01766583,
`NCT01744626, NCT01732861].
`
`ONO-4059
`ONO-4059 is a highly selective, orally bioavailable in-
`hibitor of BTK kinase activity with a potency (IC50) of
`2.2 nM. The compound covalently binds to BTK, and
`reversibly blocks BCR signaling and B-cell proliferation
`and activation. Like CC-262, ONO-4059 demonstrated
`therapeutic efficacy in a mouse CIA model by suppress-
`ing generation of inflammatory chemokines and cyto-
`kines including IL-6, IL-8, and TNFα by monocytes, and
`accompanied by regression of cartilage erosion, bone
`damage, and pannus formation [79]. The data indicate
`that ONO-4059 may have a potential benefit for the
`treatment of patients with RA. In view of
`its anti-
`proliferative activity in B-cells, ONO-4059 has progressed
`into phase I clinical trials in CLL/NHL patients with
`relapsed/refractory disease.
`
`CNX-774
`CNX-774 is another orally available, small molecule
`inhibitor with irreversible BTK-inhibitory property. CNX-
`774 is highly selective for BTK, and forms a ligand-
`directed covalent bond with the Cys-481 residue within
`the ATP binding site of the enzyme. In biochemical and
`cellular assays, CNX-774 demonstrates potent inhibitory
`activity towards BTK with an IC50 of <1nM and 1-10nM
`respectively [80]. The compound has progressed to ad-
`vanced preclinical development and additional in-vitro
`and in-vivo data are awaited.
`
`LFM-A13
`LFM-A13 is a novel, first-in-class, dual BTK/Polo-like ki-
`nases (PLK) inhibitor with anti-proliferative, pro-apoptotic,
`and chemosensitising effects in leukemia/lymphoma and
`breast cancer cells [4,81,82]. A leflunomide metabolite
`analogue, LFM-A13 binds favorably to the catalytic site
`within the kinase domain of BTK, and exhibits an inhibi-
`tory potency (IC50) of 17.2microM in cell-free kinase
`assays [83]. The compound is highly selective for BTK,
`and specifically inhibits cellular BTK activity in chicken
`lymphoma B18.2 B-cells and human NALM-6 leukemic
`pre-B cells in a dose-dependent fashion [83]. In human
`Ph+ ALL-1 and NALM-6 pre-B ALL cell line, treatment
`with LFM-A13 enhances the sensitivity of the cells to
`both ceramide- and vincristine-induced apoptosis [83].
`Dosed at levels ranging from 10 to 80 mg/kg, LFM-A13
`was not toxic to xenografted murine leukemia model
`
`[81]. The compound down-regulates BTK signaling in
`myeloma cells evident by reduced in vivo homing of
`myeloma cells to bone, prevention of myeloma-induced
`bone resorption, and moderate suppression of myeloma
`growth in primary myeloma-bearing SCID-rab mice [84].
`These preclinical data provide the rationale for future clin-
`ical development of LFM-A13 as a new therapeutic agent
`for B-cell lymphoproliferative disorders.
`
`Conclusion and future directions
`Ibrutinib, a novel BTK-targeting inhibitor, has shown
`significant activities across a variety of B-cell neoplastic
`disorders and autoimmune diseases in preclinical models
`and clinical trials. The data from clinical trials on CLL
`and mantle cell lymphoma are particularly encouraging.
`Novel BTK inhibitors, GDC-0834, HM-71224, CC-292,
`and ONO-4059, CNX-774, LFM-A13, are under active
`preclinical and clinical investigation. Among these, LFM-
`A13 represents a first-in-class dual BTK-PLK inhibitor.
`These novel inhibitors will provide new targeted therapy
`not only for B-cell lymphomas, but also for autoimmune
`disorders. Further research into combination of novel
`small molecule inhibitors against different signaling path-
`ways as well as combination of these inhibitors with other
`biological and biochemical compounds will likely enhance
`their clinical efficacy [34,85].
`
`Competing interest
`DL is a clinical investigator participating in SHINE and HELIO trials sponsored
`by Janssen. The remaining authors have no conflicts of interest.
`
`Authors’ contributions
`DL and AA were responsible for study design, data collection and drafting
`the manuscript. NM designed the figures. All authors have participated in
`manuscript development, revisions and approved the final manuscript.
`
`Acknowledgement
`Yamei Chen is supported by a grant from Xiamen Zhongshan Hospital,
`Fujian, China and by NYMC Blood Disease Fund.
`
`Author details
`1Division of Hematology/Oncology, Department of Medicine, New York
`Medical College, Valhalla, New York 10595, USA. 2Department of
`Hematology, Xiamen Zhongshan Hospital, Xiamen University, Xiamen, China.
`3Institute of Hematology, Zhengzhou University Affiliated Tumor Hospital,
`Zhengzhou, China.
`
`Received: 27 July 2013 Accepted: 18 August 2013
`Published: 19 August 2013
`
`2.
`
`References
`Liu L, Wu N, Li J: Novel targeted agents for gastric cancer. J Hematol
`1.
`Oncol 2012, 5(1):31.
`Lamba G, Ambrale S, Lee B, Gupta R, Rafiyath S, Liu D: Recent advances
`and novel agents for gastrointestinal stromal tumor (GIST). J Hematol
`Oncol 2012, 5(1):21.
`Lee B, Mukhi N, Liu D: Current management and novel agents for
`malignant melanoma. J Hematol Oncol 2012, 5(1):3.
`4. WeiSZ L, Efferth T: Polo-like kinase 1 as target for cancer therapy. Exp J
`Hematol Oncol 2012, 1(1):38.
`5. McLaughlin P, Grillo-Lopez AJ, Link BK, Levy R, Czuczman MS, Williams ME,
`Heyman MR, Bence-Bruckler I, White CA, Cabanillas F, et al: Rituximab
`chimeric anti-CD20 monoclonal antibody therapy for relapsed indolent
`
`3.
`
`SANDOZ INC.
`
`IPR2023-00478
`
`Ex. 1018, p. 7 of 9
`
`

`

`Akinleye et al. Journal of Hematology & Oncology 2013, 6:59
`http://www.jhoonline.org/content/6/1/59
`
`Page 8 of 9
`
`6.
`
`7.
`
`9.
`
`10.
`
`12.
`
`lymphoma: half of patients respond to a four-dose treatment program.
`J Clin Oncol 1998, 16(8):2825–2833.
`Colombat P, Salles G, Brouss