Brain Tumor Pathol DOI 10.1007/s10014-013-0174-9

REVIEW ARTICLE

The mechanism of chemoresistance against tyrosine kinase inhibitors in malignant glioma Mitsutoshi Nakada • Daisuke Kita • Takuya Watanabe • Yutaka Hayashi Jun-ichiro Hamada

•

Received: 31 October 2013 / Accepted: 27 December 2013 Ó The Japan Society of Brain Tumor Pathology 2014

Abstract Glioblastoma (GBM) is one of the most lethal malignancies in humans, and novel therapeutic strategies are urgently required for its treatment. Tyrosine kinases (TKs) play a pivotal role in intercellular signal transduction and regulate crucial processes of tumor cell biological activities in GBM. This information provides the basis for the molecular target therapies for GBMs. TK inhibitors (TKIs) are expected to be effective therapeutic strategies. However, one important limitation is that GBMs exhibit marked resistance to the TKIs currently available, yet the mechanisms underlying TKI resistance have not been fully characterized. In the current review, we will address the varieties of chemoresistance mechanisms against TKIs in GBM. The mechanisms responsible for TKI refractoriness in GBMs are divided into 2 aspects. The first includes tumor-related concerns, such as a lack of target expression, the multiplicity of targets, redundancy, the appearance of resistant cells, and tumor changes in characteristics. The second includes drug-related concerns, such as inefficient drug effects, delivery, pharmacokinetics, and intolerable side effects. A better understanding of these mechanisms is needed to develop accurate tests to predict the lack of response to TKIs and for developing novel approaches aimed at overcoming the resistance to TKIs. Keywords Glioma
Tyrosine kinase inhibitor
Chemoresistance

M. Nakada (&)
D. Kita
T. Watanabe
Y. Hayashi
J. Hamada Department of Neurosurgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-8641, Japan e-mail: [email protected]

Introduction Tyrosine kinases (TKs) are key regulators of cellular functions (e.g., proliferation, migration, metabolism, differentiation, and survival), and their appropriate activity is required for cellular homeostasis. Since many human diseases result from the overactivation of TKs due to mutations and/or overexpression, this enzyme class represents an important target group for disease treatment research. Receptor TKs (RTKs) represent a subclass of transmembrane proteins displaying intrinsic, ligand-controlled TK activity. Their aberrant activation is crucial in driving oncogenesis and plays a central role in cancer development through a variety of molecular mechanisms [1]. At present, various TK inhibitors (TKIs) are in clinical development and many more are in various stages of preclinical development (Table 1). Glioblastoma (GBM) is distinguished by a high degree of intratumoral heterogeneity, which extends to the pattern of expression and amplification of RTKs. Alterations in several RTKs, for example epidermal growth factor receptor (EGFR), ErbB2, platelet-derived growth factor receptor (PDGFR), and MET, have been reported in GBM [2–4]. Thus, the use of TKIs may effectively inhibit, or at least slow down, GBM cell proliferation and invasion into the surrounding brain microenvironment. Indeed, recent report has shown the efficacy of TKIs for the GBM which overexpressed certain tyrosine kinase [5]. However, almost all clinical trials using small-molecule inhibitors targeting individual RTKs have been disappointing, to date [6–8]. The focus of this review was to discuss the reasons for chemoresistance to TKIs in GBM by analyzing the tumorand drug-related aspects involved in the process. It is possible that the mechanisms controlling chemosensitivity and ways to overcome chemoresistance can be identified through GBM research.

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Brain Tumor Pathol Table 1 Tyrosine kinase inhibitors for glioblastoma Target

Agent

Other targets

EGFR Gefitinib Erlotinib Cetuximab Lapatinib

HER2

Afatinib Dacomitinib Nimotuzumab Vandetanib

VEGFR-2

Imatinib Sorafenib

c-kit, Bcr-Abl VEGFR-2, 3, BRAF, c-kit, Ras

PDGFR

MET

Cediranib

VEGFR-1, 2, 3. FGFR-1, c-kit

Sunitinib

VEGFR-2, c-kit, RET, Flt3

Tandutinib

c-kit, Flt3

Dasatinib

Src, Bcr-Abl, c-kit, EphA2

Rilotumumab Onartuzumab Cabozantinib

VEGFR2, RET

EGFR epidermal growth factor receptor, FGFR fibroblast growth factor receptor, HER2 human EGFR-related 2, PDGFR plateletderived growth factor receptor, VEGFR vascular endothelial growth factor receptor

Tumor-relevant issues The main obstacle for improving the survival of GBM with TKIs is the chemoresistance of GBM cells. Chemoresistance, almost invariably, exists in nature and/or emerges during treatment, and poses major problems for the curative therapy of GBMs. Sensitivity/resistance to tumor chemotherapy may be very complex, and oftentimes, multifactorial, with numerous genes involved [9]. Lack of target expression The paradigm of RTK genetic alterations and/or overexpression in GBM highlights a crucial clinical point; targeted therapy is effective only in patients whose target DNA contains the alteration, or target protein, which is overexpressed in the tumor. This makes the tumor susceptible to a specific drug. Thus, before subjecting patients to targeted treatments, the presence of such genetic alterations or overexpressions, which are predictive of a potential response, must be ascertained (Fig. 1) [10]. It is reasonable to speculate that the targeted drugs are not effective for patients with tumors that do not contain the target molecule, but only induce the side effects in those cases. This concept of target addiction has important

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implications for the design of molecular-targeted therapies. For example, trastuzumab is used for Her2-overexpressing breast cancer. Erlotinib is used for EGFR mutation-positive non-small cell lung cancer. However, in most clinical trials of the targeted therapies for malignant glioma patients, to date, the molecular-targeted agents have not been determined by the presence of the target molecule in the tumor tissue but have been determined by histological analysis alone (http://clinicaltrials.gov/ct). The drugs were applied to those GBM patients where the tumor tissue did not express the target protein. The results of the clinical trials were then analyzed retrospectively based on the molecular analysis of the tumor tissue and clinical response after the administration of the drugs. It seems to be ideal that the presence of target molecules are detected by simple laboratory experiments, such as enzyme-linked immunosorbent assay (ELISA), western blotting. A molecular targeting approach with TKIs in GBM treatment should start with the observation that the GBM tissue contains target molecules based on individual experimental evidence. Multiplicity of the target Multiple RTKs are possibly activated in GBMs (Fig. 1) [11]. Simultaneous activation of multiple RTKs within individual GBMs provides a theoretical mechanism for resistance. Redundant inputs drive and maintain downstream signaling [12]. This finding can explain the weak clinical responses to RTK-inhibitor monotherapies. Other unknown target TKs could be identified in future experimental analyses. The advent of next generation technologies has allowed the creation of a catalogue of cancer somatic alterations, thus revealing a number of novel, potentially therapeutic targets. Two large-scale multidimensional analyses of GBM have shed light on the mutational landscape of GBM. Studies by the Cancer Genome Atlas (TCGA) group [13] and Parsons et al. [14], through the integrated analyses of multidimensional genomic data from complementary technology platforms, identified 3 core, genetically altered pathways: (1) RTK/ RAS/PI3K, (2) p53, and (3) retinoblastoma protein (RB), which are present in nearly all GBMs. These studies offer the promise that the application of global methods can identify previously unrecognized molecular targets, and the convergence of findings from these 3 signaling networks further highlights their importance. Now, great efforts should be directed toward investigating the genetic lesions/ mutations that can be targeted for therapy. Understanding the signaling networks and studying them in patients will be critical for identifying target molecules and developing rational molecular-targeted therapies to improve the survival of GBM patients.

Brain Tumor Pathol

Fig. 1 Mechanisms of intrinsic resistance against oncological therapies. Lack of target molecules (1), multiplicity of activated TKs (2), and redundancy (3) within signaling pathways contribute each tumor cell to chemoresistance through the activation of alternative signaling pathways. A small population with stem cell phenotype remains after

cytotoxic oncological therapies because of its ability to efflux cytotoxic drugs by ABC-transporters (4). Characteristic change from proliferative into invasive phenotype stimulated by anti-angiogenic therapy enables tumor cells to escape from cytotoxic therapy (5). TK tyrosine kinase, ABC-transporters ATP-binding cassette transporters

Redundancy

not be sufficient to suppress survival or invasion signaling in GBM. To overcome the multiple target molecules and redundancy of such a multiple-input system and crosstalk among RTK signaling, the following strategies will be adopted. First, a combination of drugs against different activated RTKs might be useful. To date, the combination of EGFR inhibitors and mTOR inhibitors (sirolimus) has been applied to clinical studies. However, the results from a phase II study of erlotinib and sirolimus in patients with recurrent GBM were disappointing [20]. Second, using multi-kinase inhibitors, such as dasatinib, imatinib, sunitinib and sorafenib is another option for inhibiting the signaling cascades (Table 1). Several phase II studies using these drugs have been reported and are ongoing [17]. As a point of convergence, the third strategy is to find less redundant mediators of GBM whose inhibition will produce an effect, regardless of how many upstream signaling pathways are activated.

In contrast to the multiplicity seen in GBMs, further analysis of the TCGA dataset revealed that only 7 % showed co-amplifications of EGFR, c-MET, and/or PDGFRA, and that majority of the tumor cells harbored amplification of a single RTK in genetic alteration level [EGFR (40 %) [ PDGFRA (10 %)] [13]. In this context, molecular-targeted therapy based on the genetic character of each tumor seems to be somewhat effective for GBM. However, monotherapy with small-molecule inhibitors of EGFR, such as gefitinib and erlotinib, failed to show clear results of prolonged survival for GBM patients [15–17]. Redundancy among signaling pathways in cell physiological level is one of the possible explanations for the therapeutic failures. In essence, alternative kinase signaling pathways may be activated in parallel with the inhibited target through the feedback system and/or crosstalk among other RTKs, so that a single target’s inactivation cannot reduce downstream oncogenic signaling (Fig. 1). Furthermore, GBMs are generally heterogeneous tumors that have intratumoral mosaic amplification patterns of RTKs [18, 19]. In addition, pathways are not simply linear vectors moving from one molecule to the next, but rather complex interactive networks characterized by crosstalk and homeostatic feedback loops that can greatly influence a response to therapy. Treatment with a single RTK inhibitor, thus, may

Drug resistant cells Chemoresistance is one of the characteristics of cancer stem cell. Although the existence of Glioma stem-like cells (GSCs) is still controversial, GCS have been thought to be one of the reasons for such resistance, which persist after intensive oncological treatments and give rise to tumor

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recurrences. Paradoxically, conventional treatment for GBM [i.e., radiation with temozolomide (TMZ)], might contribute to GSCs chemoresistance. Radiation can activate Chk1 and Chk2 DNA damage check-point kinases that cause GSCs to increase their capacity to repair DNA and then escape, thus minimizing DNA damage [21, 22]. TMZ can activate drug efflux through multidrug resistance ATPbinding cassette (ABC) transporters, which has been implicated as a possible mechanism for the resistance to RTK inhibitors in GSCs (Fig. 1) [23]. Stem cells are frequently identified as the ‘‘side population (SP)’’ of a tumor by flow cytometry based on the ABCG2-mediated efflux of Hoechst dye [24]. It has been reported that SP cells appear in gliomas incubated with TMZ, particularly in PTEN null glioma cells [25]. Experimental data suggest that gefitinib and other TKIs also stimulated the ATPase activity of ABCG2, and that ABCG2 can actively extrude them from the cells [26–28]. Thus, current various oncological therapies for GBM might contribute to the appearance of drug resistant cells with GSCs properties. Strategies targeting GSCs may be necessary for the development of future therapies.

Some preclinical studies have indicated that antiVEGFR agents could increase the likelihood of tumor invasiveness through changes in gene expression. PaezRibes et al. [35] reported that the loss of VEGF/VEGFR signaling by sunitinib (a VEGFR and PDGFR inhibitor) or SU10944 (a VEGFR-selective kinase inhibitor) increased glioma invasiveness, although these agents initially demonstrated anti-tumor effects. Ebos et al. [36] showed that sunitinib increased the levels of several blood-plasma proteins that may accelerate the invasion and metastasis of tumor cells, including granulocyte colony-stimulating factor (G-CSF), stromal cell-derived factor-1a (SDF-1a), stem cell factor (SCF), and osteopontin. In the cediranib (a pan-VEGFR inhibitor) study, viable circulating endothelial cells increased when tumors escaped treatment, and circulating progenitor cells increased when tumors progressed after drug interruption [37]. Anti-RTK therapies targeting angiogenesis should, therefore, be combined with anti-invasion therapies to inhibit disease progression, although such strategies have never been tried.

Characteristic change in tumor cells

Drug-relevant issues

Glioblastoma is characterized by diffuse invasion into brain parenchyma [29, 30]. Invading glioma cells transiently undergo mitotic arrest and proliferating cells merely invade, which is known as the ‘‘migration/proliferation dichotomy’’ [29]. This phenomenon is observed, especially, during hypoxic conditions and is closely related to tumor recurrence because highly invasive cells, which are not in the DNA synthesis phase, tend to be refractory to DNA damaging agents (e.g., chemotherapy and radiotherapy) (Fig. 1). Recently, the theoretical lattice-gas cellular automaton model revealed that invasive tumor cell phenotypes with low proliferation and high motility can produce more offspring than phenotypes with much higher proliferation rates under hypoxic conditions [31]. Thus, it is not surprising that hypoxic conditions caused by antiangiogenesis therapy targeting VEGF/VEGFR signaling are associated with such characteristic changes and chemoresistance in GBM [32]. Initial responses to bevacizumab, which is a monoclonal antibody drug against vascular endothelial growth factor (VEGF) have been observed in recurrent GBMs in clinical studies. However, the tumors soon become resistant to bevacizumab, and the progression is usually quick and rapidly fatal [33, 34]. Therefore, it must be kept in mind that anti-VEGF/VEGFR treatment is a two-edged sword for GBM, since there is evidence suggesting that it increases invasive characteristics in GBM by inducing a hypoxic tumor microenvironment.

When considering TKIs by themselves, there are several reasons for their ineffectiveness against GBM that emerge. The first reason is that TKIs don’t show a significant effect against GBM. The second reason is that TKIs cannot slip through the blood–brain barrier (BBB) and enter the GBM tissue to display their effects. Furthermore, chemotherapy of glioma is notably challenging because the tumor cells reside in tissues that are considered to be pharmacological and immunological sanctuaries shielded by the BBB. The third reason is that each TKI has specific pharmacokinetics, which influences its effect on glioma. The fourth reason is the intolerable side effects induced by TKIs.

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Inefficient drug effects Clinical trials with EGFR inhibitors in GBM demonstrated poor inhibition of the EGFR signaling axis in tumor tissue, despite their successful clinical use in lung cancer. One key difference between EGFR in GBM and lung cancer is the distribution of mutations within the EGFR coding sequence. EGFR mutations in lung cancer reside in the intracellular kinase domain, whereas EGFR mutations in a GBM cluster reside in the extracellular domain and include missense and in-frame deletions, such as the common ‘‘variant III (EGFRvIII).’’ Recently, Vivanco et al. [38] provided important evidence for the single kinase addiction in GBM and suggested that the disappointing clinical activity of type I EGFR inhibitors in GBM versus lung

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cancer may be caused by the different conformational requirements of mutant EGFRs. Although TKIs are thought to be the molecular-targeted drugs, it has been found that kinase selectivity is lower than what was expected in the initial TKIs due to the simultaneous inhibition of several protein kinases. In this case, as low specificity causes a stronger cytotoxic effect, it is difficult to put into practical use. In the case of highly selective drugs, it is not always effective on all gliomas because multiple protein kinase pathways are activated in the majority of glioma cells [39]. Delivery The most crucial factor affecting the delivery of a drug to the brain and brain tumors is the transport of the agent across the BBB. The RTKs possess an extracellular ligandbinding domain and an intracellular catalytic domain with intrinsic tyrosine kinase activity. To inhibit the RTKs, all TKIs need to penetrate both the BBB and glioma cell membranes to bind to the intracellular domain of the RTKs

Fig. 2 Blood–brain/–tumor barrier and drug efflux system. TKI should bind to the intracellular domain of the specific RTK. Multiple mechanisms and barriers that limit drug delivery to glioma are evident. The intact blood brain barrier (BBB) is located in areas distant from the tumor core. Drug delivery across this barrier is restricted by the presence of tight junctions between endothelial cells and, more importantly, by drug efflux transporters that pump drugs back into the blood. The disrupted BBB is at the site of the tumor,

(Fig. 2). Although TKIs have the potential to penetrate the BBB by passive diffusion, because of its small and nonpolar molecules, early experimental studies showed that TKIs have difficulty penetrating the BBB [40]. One component of the BBB that may limit the delivery of TKIs into the central nervous system is the drug efflux transporter. ABC drug efflux transporters, such as P-glycoprotein (P-gp; ABCB1), breast cancer resistance protein (BCRP; ABCG2), and multidrug resistance protein 2 (MRP2; ABCC2) play important roles in the absorption, distribution, excretion, and toxicity of xenobiotics (Fig. 2) [41]. The BBB and the blood–tumor barrier (BTB) form sequential barriers that a systemically administered drug must cross to reach the tumor. Drug efflux transporters present in the tumor cell are a major component of this barrier and restrict intracellular drug uptake. This second barrier is especially important for TKIs. The expression of ABC transporters in human glioma cells and their role in acquired drug resistance have been studied. Several reports suggest that drug efflux transporters in tumor cells decrease intracellular drug accumulation and result in the multidrug-

with the lack of tight junctions allowing drugs and small molecules to easily diffuse into the tumor. Drug efflux transporters, which are present in the tumor cell, are a major component of the blood tumor barrier (BTB) and restrict intracellular drug uptake. Most TKIs are substrates and inhibitors of ABCB1 and ABCG2. ABC ATP-binding cassette, GBM glioblastoma, RTK receptor tyrosine kinase, TKIs tyrosine kinase inhibitors

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resistant phenotype often observed in glioma cells. Moreover, anti-cancer agents, including TMZ or gefitinib and other TKIs, would be capable of activating the ATPase of ABCG2, which results in an efflux from the cells. Previous reports from several groups show that many kinds of TKIs used in cancer therapy are substrates of both ABCB1 and ABCG2, suggesting that the interaction with these ABC transporters may also affect pharmacokinetics and the toxicity of TKIs in patients [42, 43]. The accumulation of a number of TKIs (e.g., lapatinib [44], gefitinib [45], and erlotinib [46]) in the brain appears to be significantly affected by ABCB1 and ABCG2 transporters. Enhanced permeability of drugs across the BBB may improve drug exposure and the therapeutic efficacy of invading GBM cells that are behind a functionally intact BBB. Because various drugs are excluded from the brain by such transporters, prevention of efflux transport by the use of specific inhibitors is also an attractive approach for improving the distribution of drugs in the brain [45]. An important finding in most of the studies on ABC transporters and TKIs is that the combined pharmacological inhibition of the 2 transporters significantly enhanced the levels of TKIs in the brain. Recently, several preclinical studies used elacridar, a dual inhibitor of ABCB1 and ABCG2, to reveal that complete inhibition of both transporters led to markedly increased accumulation of TKIs in the brain [47, 48]. Thus, there is currently great interest in strategies to improve the BBB penetration of anticancer drugs, especially TKIs. Pharmacokinetics The pharmacokinetic properties of TKIs are associated with their molecular weight, hydrophobicity/hydrophilicity, hydrogen bonding, and active transport. Cytochrome P450 (CYP) enzymes and various transporters also play a major role. Drug distribution plays an important role in the efficiency of TKIs with regards to GBM. All TKIs are metabolized in a very similar way [49]. Most TKIs are primarily metabolized by CYP3A4. Several TKIs (e.g., imatinib, gefitinib, and lapatinib) are inhibitors of the enzymes by which they are primarily metabolized. This could alter their metabolism substantially with multidose use across steady-state pharmacokinetics. There is little insight into steady-state metabolism at this point, which is surprising since these drugs are used on a daily basis. Some TKIs (e.g., erlotinib, sorafenib, sunitinib, and dasatinib) are thought to have no effect on CYP-enzyme activity, which might be the result of a lack of data rather than an absent effect. It is difficult to predict which type of inhibitor will show the most favorable results in patients with GBM. This is caused by similarities in physicochemical properties between TKIs and inter-individual differences in drug

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metabolism. In addition, small differences in inhibitors that are independent of the inhibitor type may show effectiveness (e.g., substrate for a drug transport pump, because most TKIs are substrates and inhibitors of ABCB1 and ABCG2). These unsolved pharmacokinetic problems would also impact the effectiveness in clinical studies of TKIs for patients with GBM. Side effects Since TKIs are designed to target specific RTKs, the strong point of a molecular target drug is the high selectivity toward tumor cells, which provides a broader therapeutic window with less toxicity. However, several clinical trials demonstrated that many TKIs trigger the appearance of undesirable side effects (Table 2). Two possible mechanisms for the observed side effects have been postulated. First, if the target molecules are expressed by cells other than the cancer cells, and they play a specific role in those cells, then the TKIs may possibly cause side effects. Second, if the target molecules interact with molecules that were beyond expectations, side effects may also arise. Because EGFR is expressed in the basal layer of the epidermis, TKI effects on EGFR inhibition by erlotinib and gefitinib lead to inflammatory cell recruitment and subsequent cutaneous injury, which accounts for most of the observed rash symptoms (Table 2). Most adverse events of TKIs seemed to be tolerable, and hematologic toxicity was rarely seen. However, co-administration of TKIs and TMZ requires special care for adverse events. Peereboom et al. [8] reported that a clinical trial utilizing a combination of irradiation, TMZ, and erlotinib for patients with newly diagnosed GBM was not efficacious and had an unacceptably high death rate (Table 2). Instead of EGFR, EGFRvIII may be a more ideal candidate for moleculartargeted therapy because EGFRvIII is not expressed in normal tissues [50]. Sunitinib, sorafenib, and imatinib were well tolerated by all patients during the initial administration in the clinical study of patients with glioma. However, they did not show clinically meaningful, anti-tumor activity.

Perspective Although kinase modulation has been shown as a novel and promising approach to treating GBM, several limitations have become apparent in clinical studies. Ongoing efforts are necessary to identify novel molecular targets and/or additional molecular pathways mediating GBM progression and chemoresistance. The tumor cell responses were determined not only by the presence of the target, but also by the molecular circuitry in which RTK-activating

96

Number of patients:

2

1

1

Respiratory 2

2 (2)a

2

3

8

0

1

0

1

1

17

Rec GBM

Lapatinib

11

137

Rec glioma

Imatinibb

3

6

0

1

4 4

5

1

9

1

3

1

1

4

0

2

5

33

Imatinib with hydroxyurea Rec GBM

8

5

2

1

9 2

1

4

1

1

60

Sorafenib with TMZb Rec GBM

1

0

3 0

0

0

1

4

1

0

Rec malignant glioma 21

Sunitinib

10

3

1

2

6

2

4

7

1

31

Rec GBM

Cediranib

1

1

14

Dasatinib with Bev Rec GBM

b

a

A combined analysis from two clinical trials

(): number of patients who died due to adverse events

Bev bevacizumab, BS brainstem, Rec recurrent, TKI tyrosine kinase inhibitor, TMZ temozolomide

The each item of non-hematologic adverse events in table include following symptoms or abnormalities. Systemic: fatigue, edema, dehydration, deep vein thrombosis; Cardiovascular: hypertension, hypotension; Central Nervous System: seizure, cerebral edema, confusion, intracerebral hemorrhage, headache, neuromotor; Cutaneous: skin toxicity (rash and dry skin), hand– foot syndrome, conjunctivitis/mucositis; Gastrointestinal: diarrhea, constipation, anorexia, nausea, vomiting, gastrointestinal toxicity (abdominal pain, stomatitis); Infection: infection without neutropenia, pneumocystis pneumonia, sepsis without neutropenia; Muscle: muscle weakness; Renal, Urinary tract: incontinence, renal toxicity, proteinuria; Respiratory: pulmonary toxicity (pulmonary edema, dyspnea); Electrolytes: hypomagnesemia, hypokalemia, hypophosphatemia; Serum data: hypoalbuminemia, bilirubin increase, ALT/AST increase, amylase/lipase increase

2

Serum data

3

6

1

3

17 4

5 (1)a

4

Electrolytes

0

1 2

14 7

5

Renal, urinary tract

3

1 2

0

Muscle

5

11 9

Cutaneous Gastrointestinal

Infection

26

Central nervous system

Cardiovascular

Systemic

Non-hematologic

Anemia

Leukopenia

Thrombocytopenia

15

7 (2)a

27

Erlotinib with TMZ [8] GBM

2

1

Rec malignant glioma 83

Erlotinibb

Lymphopenia

9

55

Rec GBM

Gefitinib

5

1

43

BS glioma (children)

Gefitinib

Febrile neutropenia

Neutropenia

Hematologic

7

GBM

Objects:

Adverse event

Gefitinib

RTKIs:

Table 2 Side effects induced by TKIs (Grade 3 or more, CTCAE ver 4.0)

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mutations occur. This suggests the necessity of overlooking the map of the individual RTK network for determining suitable TKIs that will be prescribed. In addition, biomarkers of pathway inhibition need to be developed and incorporated into a clinical trial design to determine whether the study dose effectively inhibits its target in patients. The development of new TKIs is also important. TKIs for GBM should be highly effective, specific, and capable of easily penetrating the BBB and BTB without severe, adverse effects. The understanding of pharmacokinetics and pharmacodynamics of TKIs in the brain is mandatory for the future application of TKIs for patients with GBM. The challenge for successfully treating gliomas with TKIs is one of translating genomics into functional biology, and functional biology into molecular-targeted therapy for patients. To improve the outcome of malignant glioma patients treated with targeted therapies using TKIs, we will need to link targeted agents with molecular diagnostics that identify targets and anticipate the molecular circuitry of resistance to help guide more effective combination treatments. The application of powerful, new technologies such as ‘-omics’ applications to interrogate molecular networks in clinical samples has begun to yield important insights into a better design of clinical trials with TKIs for patients with malignant gliomas. Individual and detailed molecular characterization of tumor cells, and a combination of appropriate TKIs (i.e., ‘‘individual molecular-targeted therapy’’) are expected to lead to improved therapies for treating GBM. Acknowledgments This work was supported by Grant-in-Aid for Scientific Research (C-23592117) from the Japan Society for the Promotion of Science (M. Nakada) and Takeda Science Foundation (M. Nakada). Conflict of interest

The author has no conflict of interest to declare.

References 1. Dumur CI, Idowu MO, Powers CN (2013) Targeting tyrosine kinases in cancer: the converging roles of cytopathology and molecular pathology in the era of genomic medicine. Cancer Cytopathol 121:61–71 2. Nakada M, Kita D, Watanabe T, Hayashi Y, Teng L, Pyko IV, Hamada J (2011) Aberrant signaling pathways in glioma. Cancers 3:3242–3278 3. Hegi ME, Rajakannu P, Weller M (2012) Epidermal growth factor receptor: a re-emerging target in glioblastoma. Curr Opin Neurol 25:774–779 4. Tanaka S, Louis DN, Curry WT, Batchelor TT, Dietrich J (2013) Diagnostic and therapeutic avenues for glioblastoma: no longer a dead end? Nat Rev Clin Oncol 10:14–26 5. Chi AS, Batchelor TT, Kwak EL, Clark JW, Wang DL, Wilner KD, Louis DN, Iafrate AJ (2012) Rapid radiographic and clinical improvement after treatment of a MET-amplified recurrent glioblastoma with a mesenchymal-epithelial transition inhibitor. J Clin Oncol 30:e30–e33

123

6. Prados MD, Chang SM, Butowski N, DeBoer R, Parvataneni R, Carliner H, Kabuubi P, Ayers-Ringler J, Rabbitt J, Page M, Fedoroff A, Sneed PK, Berger MS, McDermott MW, Parsa AT, Vandenberg S, James CD, Lamborn KR, Stokoe D, Haas-Kogan DA (2009) Phase II study of erlotinib plus temozolomide during and after radiation therapy in patients with newly diagnosed glioblastoma multiforme or gliosarcoma. J Clin Oncol 27:579–584 7. Raizer JJ, Abrey LE, Lassman AB, Chang SM, Lamborn KR, Kuhn JG, Yung WK, Gilbert MR, Aldape KA, Wen PY, Fine HA, Mehta M, Deangelis LM, Lieberman F, Cloughesy TF, Robins HI, Dancey J, Prados MD (2010) A phase II trial of erlotinib in patients with recurrent malignant gliomas and nonprogressive glioblastoma multiforme postradiation therapy. Neuro Oncol 12:95–103 8. Peereboom DM, Shepard DR, Ahluwalia MS, Brewer CJ, Agarwal N, Stevens GH, Suh JH, Toms SA, Vogelbaum MA, Weil RJ, Elson P, Barnett GH (2010) Phase II trial of erlotinib with temozolomide and radiation in patients with newly diagnosed glioblastoma multiforme. J Neurooncol 98:93–99 9. Mukasa A, Wykosky J, Ligon KL, Chin L, Cavenee WK, Furnari F (2010) Mutant EGFR is required for maintenance of glioma growth in vivo, and its ablation leads to escape from receptor dependence. Proc Natl Acad Sci USA 107:2616–2621 10. Weller M, Stupp R, Hegi M, Wick W (2012) Individualized targeted therapy for glioblastoma: fact or fiction? Cancer J 18:40–44 11. Szerlip NJ, Pedraza A, Chakravarty D, Azim M, McGuire J, Fang Y, Ozawa T, Holland EC, Huse JT, Jhanwar S, Leversha MA, Mikkelsen T, Brennan CW (2012) Intratumoral heterogeneity of receptor tyrosine kinases EGFR and PDGFRA amplification in glioblastoma defines subpopulations with distinct growth factor response. Proc Natl Acad Sci USA 109:3041–3046 12. Stommel JM, Kimmelman AC, Ying H, Nabioullin R, Ponugoti AH, Wiedemeyer R, Stegh AH, Bradner JE, Ligon KL, Brennan C, Chin L, DePinho RA (2007) Coactivation of receptor tyrosine kinases affects the response of tumor cells to targeted therapies. Science 318:287–290 13. Network CGAR (2008) Comprehensive genomic characterization defines human glioblastoma genes and core pathways. Nature 455:1061–1068 14. Parsons DW, Jones S, Zhang X, Lin JC, Leary RJ, Angenendt P, Mankoo P, Carter H, Siu IM, Gallia GL, Olivi A, McLendon R, Rasheed BA, Keir S, Nikolskaya T, Nikolsky Y, Busam DA, Tekleab H, Diaz LA Jr, Hartigan J, Smith DR, Strausberg RL, Marie SK, Shinjo SM, Yan H, Riggins GJ, Bigner DD, Karchin R, Papadopoulos N, Parmigiani G, Vogelstein B, Velculescu VE, Kinzler KW (2008) An integrated genomic analysis of human glioblastoma multiforme. Science 321:1807–1812 15. Rich JN, Rasheed BK, Yan H (2004) EGFR mutations and sensitivity to gefitinib. N Engl J Med 351:1260–1261 16. Mellinghoff IK, Wang MY, Vivanco I, Haas-Kogan DA, Zhu S, Dia EQ, Lu KV, Yoshimoto K, Huang JH, Chute DJ, Riggs BL, Horvath S, Liau LM, Cavenee WK, Rao PN, Beroukhim R, Peck TC, Lee JC, Sellers WR, Stokoe D, Prados M, Cloughesy TF, Sawyers CL, Mischel PS (2005) Molecular determinants of the response of glioblastomas to EGFR kinase inhibitors. N Engl J Med 353:2012–2024 17. De Witt Hamer PC (2010) Small molecule kinase inhibitors in glioblastoma: a systematic review of clinical studies. Neuro Oncol 12:304–316 18. Snuderl M, Fazlollahi L, Le LP, Nitta M, Zhelyazkova BH, Davidson CJ, Akhavanfard S, Cahill DP, Aldape KD, Betensky RA, Louis DN, Iafrate AJ (2011) Mosaic amplification of multiple receptor tyrosine kinase genes in glioblastoma. Cancer Cell 20:810–817

Brain Tumor Pathol 19. Little SE, Popov S, Jury A, Bax DA, Doey L, Al-Sarraj S, Jurgensmeier JM, Jones C (2012) Receptor tyrosine kinase genes amplified in glioblastoma exhibit a mutual exclusivity in variable proportions reflective of individual tumor heterogeneity. Cancer Res 72:1614–1620 20. Reardon DA, Desjardins A, Vredenburgh JJ, Gururangan S, Friedman AH, Herndon JE 2nd, Marcello J, Norfleet JA, McLendon RE, Sampson JH, Friedman HS (2010) Phase 2 trial of erlotinib plus sirolimus in adults with recurrent glioblastoma. J Neurooncol 96:219–230 21. Bao S, Wu Q, McLendon RE, Hao Y, Shi Q, Hjelmeland AB, Dewhirst MW, Bigner DD, Rich JN (2006) Glioma stem cells promote radioresistance by preferential activation of the DNA damage response. Nature 444:756–760 22. Huang Z, Cheng L, Guryanova OA, Wu Q, Bao S (2010) Cancer stem cells in glioblastoma–molecular signaling and therapeutic targeting. Protein Cell 1:638–655 23. Ozvegy-Laczka C, Cserepes J, Elkind NB, Sarkadi B (2005) Tyrosine kinase inhibitor resistance in cancer: role of ABC multidrug transporters. Drug Resist Update 8:15–26 24. Patrawala L, Calhoun T, Schneider-Broussard R, Zhou J, Claypool K, Tang DG (2005) Side population is enriched in tumorigenic, stem-like cancer cells, whereas ABCG2? and ABCG2cancer cells are similarly tumorigenic. Cancer Res 65:6207–6219 25. Bleau AM, Hambardzumyan D, Ozawa T, Fomchenko EI, Huse JT, Brennan CW, Holland EC (2009) PTEN/PI3K/Akt pathway regulates the side population phenotype and ABCG2 activity in glioma tumor stem-like cells. Cell Stem Cell 4:226–235 26. Ozvegy-Laczka C, Hegedus T, Varady G, Ujhelly O, Schuetz JD, Varadi A, Keri G, Orfi L, Nemet K, Sarkadi B (2004) Highaffinity interaction of tyrosine kinase inhibitors with the ABCG2 multidrug transporter. Mol Pharmacol 65:1485–1495 27. Yanase K, Tsukahara S, Asada S, Ishikawa E, Imai Y, Sugimoto Y (2004) Gefitinib reverses breast cancer resistance proteinmediated drug resistance. Mol Cancer Ther 3:1119–1125 28. Wang XK, Fu LW (2010) Interaction of tyrosine kinase inhibitors with the MDR-related ABC transporter proteins. Curr Drug Metab 11:618–628 29. Nakada M, Nakada S, Demuth T, Tran NL, Hoelzinger DB, Berens ME (2007) Molecular targets of glioma invasion. Cell Mol Life Sci 64:458–478 30. Nakada M, Kita D, Teng L, Pyko IV, Watanabe T, Hayashi Y, Hamada J (2013) Receptor tyrosine kinases: principles and functions in glioma invasion. Adv Exp Med Biol 986:143–170 31. Hatzikirou H, Basanta D, Simon M, Schaller K, Deutsch A (2012) ‘Go or grow’: the key to the emergence of invasion in tumour progression? Math Med Biol 29:49–65 32. Keunen O, Johansson M, Oudin A, Sanzey M, Rahim SA, Fack F, Thorsen F, Taxt T, Bartos M, Jirik R, Miletic H, Wang J, Stieber D, Stuhr L, Moen I, Rygh CB, Bjerkvig R, Niclou SP (2011) Anti-VEGF treatment reduces blood supply and increases tumor cell invasion in glioblastoma. Proc Natl Acad Sci USA 108:3749–3754 33. Kreisl TN, Kim L, Moore K, Duic P, Royce C, Stroud I, Garren N, Mackey M, Butman JA, Camphausen K, Park J, Albert PS, Fine HA (2009) Phase II trial of single-agent bevacizumab followed by bevacizumab plus irinotecan at tumor progression in recurrent glioblastoma. J Clin Oncol 27:740–745 34. Friedman HS, Prados MD, Wen PY, Mikkelsen T, Schiff D, Abrey LE, Yung WK, Paleologos N, Nicholas MK, Jensen R, Vredenburgh J, Huang J, Zheng M, Cloughesy T (2009) Bevacizumab alone and in combination with irinotecan in recurrent glioblastoma. J Clin Oncol 27:4733–4740 35. Paez-Ribes M, Allen E, Hudock J, Takeda T, Okuyama H, Vinals F, Inoue M, Bergers G, Hanahan D, Casanovas O (2009) Antiangiogenic therapy elicits malignant progression of tumors to

36.

37.

38.

39.

40.

41.

42.

43.

44.

45.

46.

47.

48.

increased local invasion and distant metastasis. Cancer Cell 15:220–231 Ebos JM, Lee CR, Cruz-Munoz W, Bjarnason GA, Christensen JG, Kerbel RS (2009) Accelerated metastasis after short-term treatment with a potent inhibitor of tumor angiogenesis. Cancer Cell 15:232–239 Batchelor TT, Sorensen AG, di Tomaso E, Zhang WT, Duda DG, Cohen KS, Kozak KR, Cahill DP, Chen PJ, Zhu M, Ancukiewicz M, Mrugala MM, Plotkin S, Drappatz J, Louis DN, Ivy P, Scadden DT, Benner T, Loeffler JS, Wen PY, Jain RK (2007) AZD2171, a pan-VEGF receptor tyrosine kinase inhibitor, normalizes tumor vasculature and alleviates edema in glioblastoma patients. Cancer Cell 11:83–95 Vivanco I, Robins HI, Rohle D, Campos C, Grommes C, Nghiemphu PL, Kubek S, Oldrini B, Chheda MG, Yannuzzi N, Tao H, Zhu S, Iwanami A, Kuga D, Dang J, Pedraza A, Brennan CW, Heguy A, Liau LM, Lieberman F, Yung WK, Gilbert MR, Reardon DA, Drappatz J, Wen PY, Lamborn KR, Chang SM, Prados MD, Fine HA, Horvath S, Wu N, Lassman AB, DeAngelis LM, Yong WH, Kuhn JG, Mischel PS, Mehta MP, Cloughesy TF, Mellinghoff IK (2012) Differential sensitivity of glioma- versus lung cancer-specific EGFR mutations to EGFR kinase inhibitors. Cancer Discov 2:458–471 Schwechheimer K, Huang S, Cavenee WK (1995) EGFR gene amplification—rearrangement in human glioblastomas. Int J Cancer 62:145–148 Leis JF, Stepan DE, Curtin PT, Ford JM, Peng B, Schubach S, Druker BJ, Maziarz RT (2004) Central nervous system failure in patients with chronic myelogenous leukemia lymphoid blast crisis and Philadelphia chromosome positive acute lymphoblastic leukemia treated with imatinib (STI-571). Leuk Lymphoma 45:695–698 Glavinas H, Krajcsi P, Cserepes J, Sarkadi B (2004) The role of ABC transporters in drug resistance, metabolism and toxicity. Curr Drug Deliv 1:27–42 Dai H, Marbach P, Lemaire M, Hayes M, Elmquist WF (2003) Distribution of STI-571 to the brain is limited by P-glycoproteinmediated efflux. J Pharmacol Exp Ther 304:1085–1092 Burger H, van Tol H, Boersma AW, Brok M, Wiemer EA, Stoter G, Nooter K (2004) Imatinib mesylate (STI571) is a substrate for the breast cancer resistance protein (BCRP)/ABCG2 drug pump. Blood 104:2940–2942 Polli JW, Olson KL, Chism JP, John-Williams LS, Yeager RL, Woodard SM, Otto V, Castellino S, Demby VE (2009) An unexpected synergist role of P-glycoprotein and breast cancer resistance protein on the central nervous system penetration of the tyrosine kinase inhibitor lapatinib (N-{3-chloro-4-[(3-fluorobenzyl)oxy]phenyl}-6-[5-({[2-(methylsulfonyl)ethyl]amino}methyl)-2-furyl]-4-quinazolinamine; GW572016). Drug Metab Dispos 37:439–442 Agarwal S, Manchanda P, Vogelbaum MA, Ohlfest JR, Elmquist WF (2013) Function of the blood–brain barrier and restriction of drug delivery to invasive glioma cells: findings in an orthotopic rat xenograft model of glioma. Drug Metab Dispos 41:33–39 Kodaira H, Kusuhara H, Ushiki J, Fuse E, Sugiyama Y (2010) Kinetic analysis of the cooperation of P-glycoprotein (P-gp/ Abcb1) and breast cancer resistance protein (Bcrp/Abcg2) in limiting the brain and testis penetration of erlotinib, flavopiridol, and mitoxantrone. J Pharmacol Exp Ther 333:788–796 Elmeliegy MA, Carcaboso AM, Tagen M, Bai F, Stewart CF (2011) Role of ATP-binding cassette and solute carrier transporters in erlotinib CNS penetration and intracellular accumulation. Clin Cancer Res 17:89–99 Tang SC, Lankheet NA, Poller B, Wagenaar E, Beijnen JH, Schinkel AH (2012) P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) restrict brain accumulation of the

123

Brain Tumor Pathol active sunitinib metabolite N-desethyl sunitinib. J Pharmacol Exp Ther 341:164–173 49. van Erp NP, Gelderblom H, Guchelaar HJ (2009) Clinical pharmacokinetics of tyrosine kinase inhibitors. Cancer Treat Rev 35:692–706

123

50. Del Vecchio CA, Li G, Wong AJ (2012) Targeting EGF receptor variant III: tumor-specific peptide vaccination for malignant gliomas. Expert Rev Vaccines 11:133–144