Phase I trial of erlotinib with radiation therapy in patients with glioblastoma multiforme: Results of North Central Cancer Treatment Group protocol N0177

The safety and efficacy of tyrosine kinase inhibitors against EGFR in patients with glioma; A systematic review, meta-analysis, and sub-group analysis on glioblastoma

BACKGROUND

Gliomas, particularly glioblastoma (GBM), remain challenging to treat and have a poor prognosis. Tyrosine kinase inhibitors (TKIs) targeting EGFR have shown promise, but their efficacy in gliomas is not well established. This study aimed to systematically review and meta-analyze the safety and efficacy of EGFR TKIs in patients with glioma, specifically for primary and recurrent GBM.

METHODS

A comprehensive literature search was conducted across PubMed, Embase, Scopus, and Web of Science up to January 1, 2024. Randomized controlled trials and observational studies evaluating TKIs in glioma patients were included. Primary outcomes were overall survival (OS), progression-free survival (PFS), and adverse events. A random-effects meta-analysis was performed to pool results. All statistical analysis was performed using STATA v.17.

RESULTS

A total of 2,424 patients from 51 studies were included. The pooled mean OS was 12.68 months (95 % CI: 6.29-19.08) with 1-year and 2-year OS rates of 43 % (95 % CI: 34 %-52 %) and 14 % (95 % CI: 8 %-20 %), respectively. The mean PFS was 9.61 months (95 % CI: 4.83-14.38). The overall response rate was 19 % (95 % CI: 1 %-36 %). Grade ≥ 3 adverse events occurred in 35 % of patients (95 % CI: 13 %-57 %). Subgroup analyses revealed that combination therapies outperformed TKI monotherapy, and some newer TKIs, like vandetanib, showed improved efficacy.

CONCLUSIONS

TKIs demonstrate modest but meaningful benefits in glioma treatment, particularly when combined with other therapies. While initial survival improvements are observed, long-term outcomes remain challenging. Further research is needed to develop more potent, brain-penetrant TKIs and optimize combination strategies to improve outcomes in glioma patients.

MEK Inhibition Enhances the Antitumor Effect of Radiotherapy in NF1-Deficient Glioblastoma

Individuals with neurofibromatosis type 1, an autosomal dominant neurogenetic and tumor predisposition syndrome, are susceptible to developing low-grade glioma and less commonly high-grade glioma. These gliomas exhibit loss of the neurofibromin gene [neurofibromin type 1 (NF1)], and 10% to 15% of sporadic high-grade gliomas have somatic NF1 alterations. Loss of NF1 leads to hyperactive RAS signaling, creating opportunity given the established efficacy of MEK inhibitors in plexiform neurofibromas and some individuals with low-grade glioma. We observed that NF1-deficient glioblastoma neurospheres were sensitive to the combination of an MEK inhibitor (mirdametinib) with irradiation, as evidenced by synergistic inhibition of cell growth, colony formation, and increased cell death. In contrast, NF1-intact neurospheres were not sensitive to the combination, despite complete ERK pathway inhibition. No neurosphere lines exhibited enhanced sensitivity to temozolomide combined with mirdametinib. Mirdametinib decreased transcription of homologous recombination genes and RAD51 foci, associated with DNA damage repair, in sensitive models. Heterotopic xenograft models displayed synergistic growth inhibition to mirdametinib combined with irradiation in NF1-deficient glioma xenografts but not in those with intact NF1. In sensitive models, benefits were observed at least 3 weeks beyond the completion of treatment, including sustained phosphor-ERK inhibition on immunoblot and decreased Ki-67 expression. These observations demonstrate synergistic activity between mirdametinib and irradiation in NF1-deficient glioma models and may have clinical implications for patients with gliomas that harbor germline or somatic NF1 alterations.

The need of radiotherapy optimization for glioblastomas considering immune responses

Glioblastoma is the most common of malignant primary brain tumors and one of the tumors with the poorest prognosis for which the overall survival rate has not significantly improved despite recent advances in treatment techniques and therapeutic drugs. Since the emergence of immune checkpoint inhibitors, the immune response to tumors has attracted increasing attention. Treatments affecting the immune system have been attempted for various tumors, including glioblastomas, but little has been shown to be effective. It has been found that the reason for this is that glioblastomas have a high ability to evade attacks from the immune system, and that the lymphocyte depletion associated with treatment can reduce its immune function. Currently, research to elucidate the resistance of glioblastomas to the immune system and development of new immunotherapies are being vigorously carried out. Targeting of radiation therapy for glioblastomas varies among guidelines and clinical trials. Based on early reports, target definitions with wide margins are common, but there are also reports that narrowing the margins does not make a significant difference in treatment outcome. It has also been suggested that a large number of lymphocytes in the blood are irradiated by the irradiation treatment to a wide area in a large number of fractionations, which may reduce the immune function, and the blood is being recognized as an organ at risk. Recently, a randomized phase II trial comparing two types of target definition in radiotherapy for glioblastomas was conducted, and it was reported that the overall survival and progression-free survival were significantly better in a small irradiation field group. We review recent findings on the immune response and the immunotherapy to glioblastomas and the novel role of radiotherapy and propose the need to develop an optimal radiotherapy that takes radiation effects on the immune function into account.

Anoctamins and Calcium Signalling: An Obstacle to EGFR Targeted Therapy in Glioblastoma?

Glioblastoma is the most common form of high-grade glioma in adults and has a poor survival rate with very limited treatment options. There have been no significant advancements in glioblastoma treatment in over 30 years. Epidermal growth factor receptor is upregulated in most glioblastoma tumours and, therefore, has been a drug target in recent targeted therapy clinical trials. However, while many inhibitors and antibodies for epidermal growth factor receptor have demonstrated promising anti-tumour effects in preclinical models, they have failed to improve outcomes for glioblastoma patients in clinical trials. This is likely due to the highly plastic nature of glioblastoma tumours, which results in therapeutic resistance. Ion channels are instrumental in the development of many cancers and may regulate cellular plasticity in glioblastoma. This review will explore the potential involvement of a class of calcium-activated chloride channels called anoctamins in brain cancer. We will also discuss the integrated role of calcium channels and anoctamins in regulating calcium-mediated signalling pathways, such as epidermal growth factor signalling, to promote brain cancer cell growth and migration.

Novel Receptor Tyrosine Kinase Pathway Inhibitors for Targeted Radionuclide Therapy of Glioblastoma

Glioblastoma (GB) remains the most fatal brain tumor characterized by a high infiltration rate and treatment resistance. Overexpression and/or mutation of receptor tyrosine kinases is common in GB, which subsequently leads to the activation of many downstream pathways that have a critical impact on tumor progression and therapy resistance. Therefore, receptor tyrosine kinase inhibitors (RTKIs) have been investigated to improve the dismal prognosis of GB in an effort to evolve into a personalized targeted therapy strategy with a better treatment outcome. Numerous RTKIs have been approved in the clinic and several radiopharmaceuticals are part of (pre)clinical trials as a non-invasive method to identify patients who could benefit from RTKI. The latter opens up the scope for theranostic applications. In this review, the present status of RTKIs for the treatment, nuclear imaging and targeted radionuclide therapy of GB is presented. The focus will be on seven tyrosine kinase receptors, based on their central role in GB: EGFR, VEGFR, MET, PDGFR, FGFR, Eph receptor and IGF1R. Finally, by way of analyzing structural and physiological characteristics of the TKIs with promising clinical trial results, four small molecule RTKIs were selected based on their potential to become new therapeutic GB radiopharmaceuticals.

Pediatric high-grade glioma: moving toward subtype-specific multimodal therapy

Pediatric high-grade gliomas (pHGG) comprise a deadly, heterogenous category of pediatric gliomas with a clear need for more effective treatment options. Advances in high-throughput molecular techniques have enhanced molecular understanding of these tumors, but outcomes are still poor, and treatments beyond resection and radiation have not yet been clearly established as standard of care. In this review, we first discuss the history of treatment approaches to pHGG to this point. We then review four distinct categories of pHGG, including histone 3-mutant, IDH-mutant, histone 3/IDH-wildtype, and radiation-induced pHGG. We discuss the molecular understanding of each subgroup and targeted treatment options in development. Finally, we look at the development and current status of two novel approaches to pHGG as a whole: localized convection-enhanced chemotherapy delivery and immunotherapy, including checkpoint inhibitors, vaccine therapy, and CAR-T cells. Through this review, we demonstrate the potential for rational, molecularly driven, subtype-specific therapy to be used with other novel approaches in combinations that could meaningfully improve the prognosis in pHGG.

Pharmacokinetics and safety of erlotinib and its metabolite OSI-420 in infants and children with primary brain tumors

PURPOSE

Erlotinib (Tarceva®), a potent small molecule inhibitor of the epidermal growth factor receptor tyrosine kinase, has been evaluated to treat infants and children with primary brain tumors. The pharmacokinetics of erlotinib and its primary metabolite OSI-420 were characterized and exposure-safety associations were investigated.

METHODS

This analysis involved patients enrolled in two clinical studies and receiving oral erlotinib once daily as part of treatment. Single-dose and steady-state erlotinib and OSI-420 plasma concentrations were assayed using HPLC-MS/MS methods. Population pharmacokinetic modeling and univariate covariate analysis evaluating demographic, clinical and selected CYP3A5, CYP3A4, ABCB1, and ABCG2 genotypes were performed. Associations between erlotinib and OSI-420 pharmacokinetics, and with toxicities (diarrhea and skin rash) occurring post-dose were explored.

RESULTS

Data from 47 patients (0.7-19 years old) were collected and best fitted by one-compartment linear models. Erlotinib and OSI-420 apparent clearances (CL/F and CLm/Fm) were higher in patients < 5 years compared to older patients (mean CL/F: 6.8 vs 3.6 L/h/m2, and mean CLm/Fm: 79 vs 38 L/h/m2, p < 0.001), and were 1.62-fold and 1.73-fold higher in males compared to females (p < 0.01). Moreover, CL/F was 1.53-fold higher in wild-type patients than in patients heterozygous or homozygous mutant for ABCG2 rs55930652 (p < 0.05). Most of the toxicities reported were grade 1. No associations were found between drug pharmacokinetics and drug-induced toxicities.

CONCLUSIONS

Erlotinib therapy was well tolerated by pediatric patients with primary brain tumors. No dosing adjustments based on age or patient characteristics are recommended for this patient population.

Glioblastoma targeted therapy: updated approaches from recent biological insights

Glioblastoma (WHO grade IV astrocytoma) is the most frequent primary brain tumor in adults, representing a highly heterogeneous group of neoplasms that are among the most aggressive and challenging cancers to treat. An improved understanding of the molecular pathways that drive malignancy in glioblastoma has led to the development of various biomarkers and the evaluation of several agents specifically targeting tumor cells and the tumor microenvironment. A number of rational approaches are being investigated, including therapies targeting tumor growth factor receptors and downstream pathways, cell cycle and epigenetic regulation, angiogenesis and antitumor immune response. Moreover, recent identification and validation of prognostic and predictive biomarkers have allowed implementation of modern trial designs based on matching molecular features of tumors to targeted therapeutics. However, while occasional targeted therapy responses have been documented in patients, to date no targeted therapy has been formally validated as effective in clinical trials. The lack of knowledge about relevant molecular drivers in vivo combined with a lack of highly bioactive and brain penetrant-targeted therapies remain significant challenges. In this article, we review the most promising biological insights that have opened the way for the development of targeted therapies in glioblastoma, and examine recent data from clinical trials evaluating targeted therapies and immunotherapies. We discuss challenges and opportunities for the development of these agents in glioblastoma.

Novel chemotherapeutics and other therapies for treating high-grade glioma

INTRODUCTION

Despite extensive research, high-grade glioma (HGG) remains a dire diagnosis with no change in the standard of care in almost a decade. However, recent advancements uncovering molecular biomarkers of brain tumors and tumor-specific antigens targeted by immunotherapies provide opportunities for novel personalized treatment regimens to improve survival.

AREAS COVERED

In this review, the authors provide a comprehensive overview of recent therapeutic advancements in HGG. Furthermore, they describe new molecular biomarkers and molecular classifications, in addition to updated research on bevacizumab, targeted molecular therapies, immunotherapy and alternative delivery methods that overcome the blood-brain barrier to reach the target tumor tissue. Challenges regarding each therapy are also outlined. The authors also provide some insight into a novel non-chemotherapeutic treatment for malignant glioma, NovoTTFA, as well as a summary of current treatment options for recurrence.

EXPERT OPINION

Current research for treating malignant gliomas are paving the path to personalized therapy, including immunotherapy, that involve integrated genomic and histolopathologic data, as well as a multi-modal treatment regimen. Immunotherapy will potentially be the next addition to the current standard of care, specialized to the antigens presented on the tumors. The results of the current trials of multi-antigen vaccines are eagerly anticipated.

Targeted molecular therapies against epidermal growth factor receptor: past experiences and challenges

Epidermal growth factor receptor (EGFR) has emerged as a highly attractive therapeutic target in glioblastoma (GBM) based on its high frequency of gene amplification and mutation and its identification as an upstream trigger of dysregulated cell signaling cascades that drive GBM pathophysiology. Extensive investment has been committed in an attempt to exploit EGFR therapeutically to improve outcome for GBM patients, including the development of a variety of EGFR-targeting therapeutics as well as the participation of hundreds of participants in multiple, carefully constructed clinical trials. In this review, we summarize the design and results of clinical trials evaluating EGFR tyrosine kinase inhibitors in recurrent and newly diagnosed GBM patients. While overall results thus far have been disappointing, it is premature to discount EGFR as a therapeutic target in GBM on the basis of these studies given the limitations in study design and the pharmacology of first-generation EGFR kinase inhibitors. Although important lessons have been learned, critical questions remain unanswered and warrant further study.

Challenges to targeting epidermal growth factor receptor in glioblastoma: escape mechanisms and combinatorial treatment strategies

Epidermal growth factor receptor (EGFR) gene amplification and activating mutations are common findings in glioblastomas. EGFR is at the top of a downstream signaling cascade that regulates important characteristics of glioblastoma cells, including cellular proliferation, migration, and survival. Targeting EGFR has therefore been regarded as a promising therapeutic strategy in glioblastoma for decades. However, although various pharmacological inhibitors and anti-EGFR antibodies are available, the antiglioma activity of these agents has been largely limited to preclinical models, whereas their administration to glioblastoma patients was characterized by lack of clinical benefit. Comprehensive efforts have been made within the last years to understand the underlying mechanisms that confer resistance to EGFR inhibition in glioma cells. The absence of well-known mutations that predict response to EGFR tyrosine kinase inhibitors (TKIs) in gliomas as well as the presence of redundant and alternative compensatory pathways are among the most important escape mechanisms that prevent potent antiglioma effects of EGFR-targeting drugs. Accordingly, an increasing number of in vitro and in vivo studies are aimed at overcoming this resistance by combinatorial approaches using anti-EGFR treatment together with one or more additional drugs. Novel insights into the molecular mechanisms mediating resistance to anti-EGFR treatment and promising combinatorial approaches may help to better define a future role for EGFR inhibition in the treatment of glioblastoma.

Systematic review and meta-analysis of phase I/II targeted therapy combined with radiotherapy in patients with glioblastoma multiforme: quality of report, toxicity, and survival

To perform a systematic review and meta-analysis of severe adverse events (SAE) reported in early trials combining molecularly targeted therapies (MTT) with radiotherapy (RT), and to compare them to standard therapy. A summary data meta-analysis was performed and compared to the historical standard. Inclusion criteria were phase I and/or II trials published between 2000 and 2011, with glioblastoma multiforme patients treated with RT and MTT. Pooled incidence rates (IR) of SAE were estimated as well as the pooled median progression-free survival (PFS) and overall survival (OS). Nineteen prospective trials (9 phase I, 1 phase I/II and 9 phase II) out of 29 initially selected were included (n = 755 patients). The exact number of patients who had experienced SAE was mentioned in 37 % of the trials, concerning only 17 % of the patients. Information such as the period during which adverse events were monitored, the planned treatment duration, and late toxicity were not reported in the trials. The pooled IR of overall SAE was 131.2 (95 % CI 88.8-193.7) per 1000 person-months compared to 74.7 (63.6-87.8) for standard therapy (p < 0.01). Significant differences were observed for gastrointestinal events (p = 0.05) and treatment-related deaths (p = 0.02), in favour of standard therapy. No significant difference was observed in PFS and OS. Reporting a summary of toxicity data in early clinical trials should be stringently standardized. The use of MTT with RT compared to standard therapy increased SAE while yielded comparable survival in glioblastoma multiforme patients.

Fighting cancer drug resistance: Opportunities and challenges for mutation-specific EGFR inhibitors

Multiple mutations in the EGFR gene are a major cause for the failure of Erlotinib and Gefitinib in the treatment of patients harboring non-small-cell lung cancer (NSCLC) who initially responded to this therapy. The development of these tyrosine kinase inhibitors (TKIs) is going back to the early 90s, where cancer was widely considered and fully treated as a disease of an organ. Fundamental gain of knowledge in cell biology in general and cancer genetics in particular led us to where we currently stand: cancer is a disease that originates in the genome. Fast and affordable gene sequencing paved the way and opened our eyes for the genetic instability of many cancers, particularly EGFR driven NSCLC. This might allow highly rational and personal therapies by aiming at a very particular wild type and mutant kinase pattern. However, the paradigm "one disease - one target - one drug" is currently challenged. Both activating and deactivating EGFR mutations are known to render the development of novel targeted drugs difficult. Among all lung adenocarcinomas, only 20% are driven by EGFR and only a subpopulation has an activating mutation (e.g. L858R), making them sensitive to first generation EGFR inhibitors. Unfortunately, most of them acquire second deactivating mutations (e.g. T790M) during treatment, leading to a complete loss of response. Are specific inhibitors of the double EGFR mutant L858R/T790M the magic bullet? Much scientific evidence but also high expectations justify this approach. Structural biology of EGFR mutants constitutes the basis for highly rational approaches. Second generation pan EGFR inhibitors inhibiting wild type (WT) and mutant EGFR like Afatinib suffer from dose-limiting adverse effects. Inhibition of WT EGFR is considered to be the culprit. Third generation EGFR inhibitors follow two strategies. Mutant selectivity and improved target residential time. These inhibitors display high mutant selectivity and irreversible binding patterns while sparing WT EGFR activity, hence enhancing tumor selectivity while minimizing adverse effects. Third generation EGFR inhibitors are still undergoing preclinical and clinical evaluation. The most advanced are Rociletinib and AZD9291 which displayed encouraging preliminary clinical phase II data regarding response and adverse effects. In the current review we show both a medicinal chemists' approach toward the design of third generation EGFR inhibitors as well as a detailed overview of the development of EGFR inhibitors over the last decade. High interdisciplinary approaches, such as structural biology and time-resolved tumor genetics pave the way toward the development of drugs that target EGFR mutants. This might lead to highly effective targeted and personalized therapies with enhanced response rates for a minor cohort of patients which have to undergo continuous gene sequencing, hence enabling therapies with tailor-made TKIs.

Targeting core (mutated) pathways of high-grade gliomas: challenges of intrinsic resistance and drug efflux

High-grade gliomas are the most common type of primary brain tumor and are among the most lethal types of human cancer. Most patients with a high-grade glioma have glioblastoma multiforme (GBM), the most malignant glioma subtype that is associated with a very aggressive disease course and short overall survival. Standard treatment of newly diagnosed GBM involves surgery followed by chemoradiation with temozolomide. However, despite this extensive treatment the mean overall survival is still only 14.6 months and more effective treatments are urgently needed. Although different types of GBMs are indistinguishable by histopathology, novel molecular pathological techniques allow discrimination between the four main GBM subtypes. Targeting the aberrations in the molecular pathways underlying these subtypes is a promising strategy to improve therapy. In this article, we will discuss the potential avenues and pitfalls of molecularly targeted therapies for the treatment of GBM.

Current medical treatment of glioblastoma

Glioblastoma is the most common adult malignant primary brain tumor. Despite the advances in therapeutic options, survival of patients with glioblastoma remains dismal at 15-18 months. Current standard of care for newly diagnosed glioblastoma is maximal possible safe resection consistent with the preservation of neurologic function followed by concurrent temozolomide with radiation and adjuvant. Treatment options at recurrence include surgical resection with or without the placement of carmustine wafers, re-irradiation and chemotherapeutics such as nitrosoureas (lomustine, carmustine) or bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor (VEGF).

Targeted therapy in gliomas

The survival outcome of patients with malignant gliomas is still poor, despite advances in surgical techniques, radiation therapy and the development of novel chemotherapeutic agents. The heterogeneity of molecular alterations in signaling pathways involved in the pathogenesis of these tumors contributes significantly to their resistance to treatment. Several molecular targets for therapy have been discovered over the last several years. Therapeutic agents targeting these signaling pathways may provide more effective treatments and may improve survival. This review summarizes the important molecular therapeutic targets and the outcome of published clinical trials involving targeted therapeutic agents in glioma patients.

Contemporary murine models in preclinical astrocytoma drug development

Despite 6 decades of research, only 3 drugs have been approved for astrocytomas, the most common malignant primary brain tumors. However, clinical drug development is accelerating with the transition from empirical, cytotoxic therapy to precision, targeted medicine. Preclinical animal model studies are critical for prioritizing drug candidates for clinical development and, ultimately, for their regulatory approval. For decades, only murine models with established tumor cell lines were available for such studies. However, these poorly represent the genomic and biological properties of human astrocytomas, and their preclinical use fails to accurately predict efficacy in clinical trials. Newer models developed over the last 2 decades, including patient-derived xenografts, genetically engineered mice, and genetically engineered cells purified from human brains, more faithfully phenocopy the genomics and biology of human astrocytomas. Harnessing the unique benefits of these models will be required to identify drug targets, define combination therapies that circumvent inherent and acquired resistance mechanisms, and develop molecular biomarkers predictive of drug response and resistance. With increasing recognition of the molecular heterogeneity of astrocytomas, employing multiple, contemporary models in preclinical drug studies promises to increase the efficiency of drug development for specific, molecularly defined subsets of tumors.

Medical therapy of gliomas

Medical therapies are an important part of adjunctive therapy for gliomas. In this chapter we will review the chemotherapeutic and targeted agents that have been evaluated in clinical trials in grade II-IV gliomas in the last decade. A number of randomized phase III trials were completed and reported. There has been a clear success in oligodendroglial tumors and low grade glioma. Although some progress has been made in glioblastoma, considerable work involving the multidisciplinary collaboration of basic science, translational and clinical investigators needs to be done to improve the outcome of patients with anaplastic astrocytoma and glioblastoma. In addition, tailoring treatment based on molecular cytogenetic characteristics is a major focus of research into precision based medicine for glioma.

Combining molecular targeted agents with radiation therapy for malignant gliomas

The expansion in understanding the molecular biology that characterizes cancer cells has led to the rapid development of new agents to target important molecular pathways associated with aberrant activation or suppression of cellular signal transduction pathways involved in gliomagenesis, including epidermal growth factor receptor, vascular endothelial growth factor receptor, mammalian target of rapamycin, and integrins signaling pathways. The use of antiangiogenic agent bevacizumab, epidermal growth factor receptor tyrosine kinase inhibitors gefitinib and erlotinib, mammalian target of rapamycin inhibitors temsirolimus and everolimus, and integrin inhibitor cilengitide, in combination with radiation therapy, has been supported by encouraging preclinical data, resulting in a rapid translation into clinical trials. Currently, the majority of published clinical studies on the use of these agents in combination with radiation and cytotoxic therapies have shown only modest survival benefits at best. Tumor heterogeneity and genetic instability may, at least in part, explain the poor results observed with a single-target approach. Much remains to be learned regarding the optimal combination of targeted agents with conventional chemoradiation, including the use of multipathways-targeted therapies, the selection of patients who may benefit from combined treatments based on molecular biomarkers, and the verification of effective blockade of signaling pathways.

Restricted brain penetration of the tyrosine kinase inhibitor erlotinib due to the drug transporters P-gp and BCRP

PURPOSE

Erlotinib (Tarceva®, OSI-774) is a small molecule inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase. As high-grade gliomas frequently show amplification, overexpression and/or mutation of EGFR, this drug has been tested in several clinical trials with glioblastoma patients, but unfortunately, with little success. As erlotinib is a known substrate of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) we have investigated the effect of these ABC-transporters on the brain penetration of erlotinib.

STUDY DESIGN

Erlotinib (50 mg/kg) was given by i.p. administration to wild-type (WT), Mdr1ab(-/-) (single P-gp knockout), Bcrp1(-/-) (single Bcrp1 knockout) and Mdr1ab(-/-)Bcrp1(-/-) (compound P-gp and Bcrp1 knockout) mice. Drug levels in plasma and tissues were determined by reversed-phase high-performance liquid chromatography.

RESULTS

Relative to Mdr1ab(-/-)Bcrp1(-/-) mice that are deficient for both drug transporters, the area under the concentration time curve in brain tissue (AUC)(brain) of erlotinib decreased significantly by 1.6-fold in Mdr1ab(-/-) mice where Bcrp1 is present (49.6 ± 3.95 versus 31.1 ± 1.7, μg/g*h; P < 0.01). In Bcrp1(-/-) mice, were P-gp is present, a more pronounced 3.8-fold decrease to 13.0 ± 0.70, μg/g*h (P < 0.01) was observed, which is close to the 4.5-fold decrease in the AUC(brain) of erlotinib found in WT mice where both drug transporters are present (11.0 ± 1.35, P < 0.01). The plasma clearance of erlotinib was similar in mice deficient for P-gp and/or Bcrp1 compared with wild-type mice. In all other tissues the differences between the genotypes were negligible.

CONCLUSIONS

Both P-gp and Bcrp1 reduce the brain penetration of erlotinib. Although P-gp appears to be the most effective factor limiting the brain penetration of erlotinib, the highest brain accumulation was observed when Bcrp1 was also absent. Strategies to inhibit P-gp/BCRP in patients to improve delivery of (novel molecular-targeted) substrate agents, such as erlotinib, to the brain may be required for treatment of intracranial malignancies.

Intratumoral heterogeneity of receptor tyrosine kinases EGFR and PDGFRA amplification in glioblastoma defines subpopulations with distinct growth factor response

Glioblastoma (GBM) is distinguished by a high degree of intratumoral heterogeneity, which extends to the pattern of expression and amplification of receptor tyrosine kinases (RTKs). Although most GBMs harbor RTK amplifications, clinical trials of small-molecule inhibitors targeting individual RTKs have been disappointing to date. Activation of multiple RTKs within individual GBMs provides a theoretical mechanism of resistance; however, the spectrum of functional RTK dependence among tumor cell subpopulations in actual tumors is unknown. We investigated the pattern of heterogeneity of RTK amplification and functional RTK dependence in GBM tumor cell subpopulations. Analysis of The Cancer Genome Atlas GBM dataset identified 34 of 463 cases showing independent focal amplification of two or more RTKs, most commonly platelet-derived growth factor receptor α (PDGFRA) and epidermal growth factor receptor (EGFR). Dual-color fluorescence in situ hybridization was performed on eight samples with EGFR and PDGFRA amplification, revealing distinct tumor cell subpopulations amplified for only one RTK; in all cases these predominated over cells amplified for both. Cell lines derived from coamplified tumors exhibited genotype selection under RTK-targeted ligand stimulation or pharmacologic inhibition in vitro. Simultaneous inhibition of both EGFR and PDGFR was necessary for abrogation of PI3 kinase pathway activity in the mixed population. DNA sequencing of isolated subpopulations establishes a common clonal origin consistent with late or ongoing divergence of RTK genotype. This phenomenon is especially common among tumors with PDGFRA amplification: overall, 43% of PDGFRA-amplified GBM were found to have amplification of EGFR or the hepatocyte growth factor receptor gene (MET) as well.

Radiotherapy and "new" drugs-new side effects?

BACKGROUND AND PURPOSE

Targeted drugs have augmented the cancer treatment armamentarium. Based on the molecular specificity, it was initially believed that these drugs had significantly less side effects. However, currently it is accepted that all of these agents have their specific side effects. Based on the given multimodal approach, special emphasis has to be placed on putative interactions of conventional cytostatic drugs, targeted agents and other modalities. The interaction of targeted drugs with radiation harbours special risks, since the awareness for interactions and even synergistic toxicities is lacking. At present, only limited is data available regarding combinations of targeted drugs and radiotherapy. This review gives an overview on the current knowledge on such combined treatments.

MATERIALS AND METHODS

Using the following MESH headings and combinations of these terms pubmed database was searched: Radiotherapy AND cetuximab/trastuzumab/panitumumab/nimotuzumab, bevacizumab, sunitinib/sorafenib/lapatinib/gefitinib/erlotinib/sirolimus, thalidomide/lenalidomide as well as erythropoietin. For citation crosscheck the ISI web of science database was used employing the same search terms.

RESULTS

Several classes of targeted substances may be distinguished: Small molecules including kinase inhibitors and specific inhibitors, antibodies, and anti-angiogenic agents. Combination of these agents with radiotherapy may lead to specific toxicities or negatively influence the efficacy of RT. Though there is only little information on the interaction of molecular targeted radiation and radiotherapy in clinical settings, several critical incidents are reported.

CONCLUSIONS

The addition of molecular targeted drugs to conventional radiotherapy outside of approved regimens or clinical trials warrants a careful consideration especially when used in conjunction in hypo-fractionated regimens. Clinical trials are urgently needed in order to address the open question in regard to efficacy, early and late toxicity.

Innovative Therapies against Human Glioblastoma Multiforme

Glioblastoma multiforme is the most invasive and aggressive brain tumor in humans, and despite the latest chemical and radiative therapeutic approaches, it is still scarcely sensitive to these treatments and is generally considered an incurable disease. This paper will focus on the latest approaches to the treatment of this cancer, including the new chemicals such as proautophagic drugs and kinases inhibitors, and differentiating agents. In this field, there have been opening new perspectives as the discovery of possible specific targets such as the EGFRvIII, a truncated form of the EGF receptor. Antibodies against these targets can be used as proapoptotic agents and as possible carriers for chemicals, drugs, radioisotopes, and toxins. In this paper, we review the possible mechanism of action of these therapies, with particular attention to the combined use of toxic substances (for example, immunotoxins) and antiproliferative/differentiating compounds (i.e., ATRA, PPARγ agonists). All these aspects will be discussed in the view of progress clinical trials and of possible new approaches for directed drug formulations.

Innovative Therapies for Children with Cancer pediatric phase I study of erlotinib in brainstem glioma and relapsing/refractory brain tumors

This multicenter phase I study aimed to establish the recommended dose (RD) of the epidermal growth factor receptor (EGFR) inhibitor erlotinib, given as monotherapy or with radiotherapy to children with malignant brain tumors. Group 1 included patients with refractory or relapsing brain tumors receiving erlotinib alone, and group 2 included newly diagnosed patients with brainstem gliomas receiving radiotherapy and erlotinib. A conventional 3 + 3 dose escalation and a continual reassessment method, respectively, were utilized in 4 dose levels: 75, 100, 125, and 150 mg/m² per day. Fifty-one children were enrolled (30 and 21, respectively); 50 received treatment. The RD of erlotinib was 125 mg/m² per day as monotherapy or in combination with radiotherapy. Overall, 230 adverse events in 44 patients were possibly treatment related (216, grades 1 and 2; 9, grade 3; 1, grade 4; 4, grade 5). Dermatologic and neurologic symptoms were common; intratumoral hemorrhage was confirmed in 3 patients. In group 1, 8 of 29 patients (28%) had stable disease with tumor regression approaching 50% in a malignant glioma and an anaplastic oligoastrocytoma. In group 2, overall survival was 12.0 months. EGFR overexpression by immunohistochemistry was found in 17 of 38 (45%) tumor samples analyzed, with a partial gain of 7p11.2 in 1 glioblastoma; phosphate and tensin homolog loss was frequent in brainstem glioma (15 of 19). Mean (95% CI) apparent clearance and volume of distribution for erlotinib were 4.0 L/h (3.4-4.5 L/h) and 98.6 L (69.8-127.0 L), respectively, and were independent of the dose level; mean half-life was 16.6 hours. Thus, erlotinib 125 mg/m² per day has an acceptable tolerability profile in pediatric patients with brain tumors and can be combined with radiotherapy.

Combination of temsirolimus (CCI-779) with chemoradiation in newly diagnosed glioblastoma multiforme (GBM) (NCCTG trial N027D) is associated with increased infectious risks

PURPOSE

The mammalian target of rapamycin (mTOR) functions within the phosphoinositide 3-kinase/Akt signaling pathway as a critical modulator of cell survival.

METHODS

The mTOR inhibitor temsirolimus (CCI-779) was combined with chemoradiotherapy in glioblastoma multiforme (GBM) patients in a dose-escalation phase I trial. The first 12 patients were treated with CCI-779 combined with radiation/temozolomide and adjuvant temozolomide. A second cohort of 13 patients was treated with concurrent CCI-779/radiation/temozolomide followed by adjuvant temozolomide monotherapy.

RESULTS

Concomitant and adjuvant CCI-779 was associated with a high rate (3 of 12 patients) of grade 4/5 infections. By limiting CCI-779 treatment to the radiation/temozolomide phase and using antibiotic prophylaxis, the rate of infections was reduced, although 2 of 13 patients developed exacerbation of pre-existing fungal or viral infections. Dose-limiting toxicities were observed in 2 of 13 patients with this modified schedule. Weekly CCI-779 (50 mg/week) combined with radiation/temozolomide is the recommended phase II dose and schedule. The immune profile of patients in the second cohort was assessed before, during, and after CCI-779 therapy. There was robust suppression of helper and cytotoxic T cells, B cells, natural killer, cells and elevation of regulatory T cells during CCI-779/radiation/temozolomide therapy with recovery to baseline levels during adjuvant temozolomide of cytotoxic T cells, natural killer cells, and regulatory T cells.

CONCLUSIONS

The increased infection rate observed with CCI-779 combined with chemoradiotherapy in GBM was reduced with antibiotic prophylaxis and by limiting the duration of CCI-779 therapy. The combined suppressive effects of CCI-779 and temozolomide therapy on discrete immune compartments likely contributed to the increased infectious risks observed.

North Central Cancer Treatment Group Phase I trial N057K of everolimus (RAD001) and temozolomide in combination with radiation therapy in patients with newly diagnosed glioblastoma multiforme

BACKGROUND

The mammalian target of rapamycin (mTOR) functions within the PI3K/Akt signaling pathway as a critical modulator of cell survival. On the basis of promising preclinical data, the safety and tolerability of therapy with the mTOR inhibitor RAD001 in combination with radiation (RT) and temozolomide (TMZ) was evaluated in this Phase I study.

METHODS AND MATERIALS

All patients received weekly oral RAD001 in combination with standard chemoradiotherapy, followed by RAD001 in combination with standard adjuvant temozolomide. RAD001 was dose escalated in cohorts of 6 patients. Dose-limiting toxicities were defined during RAD001 combination therapy with TMZ/RT.

RESULTS

Eighteen patients were enrolled, with a median follow-up of 8.4 months. Combined therapy was well tolerated at all dose levels, with 1 patient on each dose level experiencing a dose-limiting toxicity: Grade 3 fatigue, Grade 4 hematologic toxicity, and Grade 4 liver dysfunction. Throughout therapy, there were no Grade 5 events, 3 patients experienced Grade 4 toxicities, and 6 patients had Grade 3 toxicities attributable to treatment. On the basis of these results, the recommended Phase II dosage currently being tested is RAD001 70 mg/week in combination with standard chemoradiotherapy. Fluorodeoxyglucose (FDG) positron emission tomography scans also were obtained at baseline and after the second RAD001 dose before the initiation of TMZ/RT; the change in FDG uptake between scans was calculated for each patient. Fourteen patients had stable metabolic disease, and 4 patients had a partial metabolic response.

CONCLUSIONS

RAD001 in combination with RT/TMZ and adjuvant TMZ was reasonably well tolerated. Changes in tumor metabolism can be detected by FDG positron emission tomography in a subset of patients within days of initiating RAD001 therapy.

EGFR-targeted therapy in malignant glioma: novel aspects and mechanisms of drug resistance

Glioblastoma, GBM, is the most frequent brain malignancy in adults. Patients with these tumors survive only, approximately, one year after diagnosis and rarely survive beyond two years. This poor prognosis is, in part, due to our insufficient understanding of the complex aggressive nature of these tumors and the lack of effective therapy. In GBM, over-expression of EGFR and/or its constitutively activated variant EGFRvIII is a major characteristic and is associated with tumorigenesis and more aggressive phenotypes, such as, invasiveness and therapeutic resistance. Consequently, both have been major targets for GBM therapy, however, clinical trials of EGFR- and EGFRvIII-targeted therapies have yielded unsatisfactory results and the molecular basis for the poor results is still unclear. Thus, in this review, we will summarize results of recent clinical trials and recent advances made in the understanding of the EGFR/EGFRvIII pathways with a key focus on those associated with intrinsic resistance of GBM to EGFR-targeted therapy. For example, emerging evidence indicates an important role that PTEN plays in predicting GBM response to EGFR-targeted therapy. Aberrant Akt/mTOR pathway has been shown to contribute to the resistant phenotype. Also, several studies have reported that EGFR/EGFRvIII's cross-talk with the oncogenic transcription factorSTAT3 and receptor tyrosine kinases, (c-Met and PDGFR) potentially lead to GBM resistance to anti-EGFR therapy. Other emerging mechanisms, including one involving HMG-CoA reductase, will also be discussed in this mini-review. These recent findings have provided new insight into the highly complex and interactive nature of the EGFR pathway and generated rationales for novel combinational targeted therapies for these tumors.

Small molecule kinase inhibitors in glioblastoma: a systematic review of clinical studies

The efficacy of small-molecule kinase inhibitors has recently changed standard clinical practice for several solid cancers. Glioblastoma is a solid cancer that universally recurs and unrelentingly results in death despite maximal surgery and radiotherapy with concomitant and adjuvant temozolomide. Several clinical studies using kinase inhibitors in glioblastoma have been reported. The present study systematically reviews the efficacy, toxicity, and tissue analysis of small-molecule kinase inhibitors in adult patients with glioblastoma as reported in published clinical studies and determines which kinases have been targeted by the inhibitors used in these studies. Publications were retrieved using a MEDLINE search and by screening meeting abstracts. A total of 60 studies qualified for inclusion, of which 25 were original reports. A total of 2385 glioblastoma patients receiving kinase inhibitors could be evaluated. The study designs included 2 phase III studies and 37 phase II studies. Extracted data included radiological response, progression-free survival, overall survival, toxicity, and biomarker analysis. The main findings were that (i) efficacy of small-molecule kinase inhibitors in clinical studies with glioblastoma patients does not yet warrant a change in standard clinical practice and (ii) 6 main kinase targets for inhibitors have been evaluated in these studies: EGFR, mTOR, KDR, FLT1, PKCbeta, and PDGFR.

A phase II trial of erlotinib in patients with recurrent malignant gliomas and nonprogressive glioblastoma multiforme postradiation therapy

Patients with (a) recurrent malignant glioma (MG): glioblastoma (GBM) or recurrent anaplastic glioma (AG), and (b) nonprogressive (NP) GBM following radiation therapy (RT) were eligible. Primary objective for recurrent MG was progression-free survival at 6 months (PFS-6) and overall survival at 12 months for NP GBM post-RT. Secondary objectives for recurrent MGs were response, survival, assessment of toxicity, and pharmacokinetics (PKs). Treatment with enzyme-inducing antiepileptic drugs was not allowed. Patients received 150 mg/day erlotinib. Patients requiring surgery were treated 7 days prior to tumor removal for PK analysis and effects of erlotinib on epidermal growth factor receptor (EGFR) and intracellular signaling pathways. Ninety-six patients were evaluable (53 recurrent MG and 43 NP GBM); 5 patients were not evaluable for response. PFS-6 in recurrent GBM was 3% with a median PFS of 2 months; PFS-6 in recurrent AG was 27% with a median PFS of 2 months. Twelve-month survival was 57% in NP GBMs post-RT. Primary toxicity was dermatologic. The tissue-to-plasma ratio normalized to nanograms per gram dry weight for erlotinib and OSI-420 ranged from 25% to 44% and 30% to 59%, respectively, for pretreated surgical patients. No effect on EGFR or intratumoral signaling was seen. Patients with NP GBM post-RT who developed rash in cycle 1 had improved survival (P < .001). Single-agent activity of erlotinib is minimal for recurrent MGs and marginally beneficial following RT for NP GBM patients. Development of rash in cycle 1 correlates with survival in patients with NP GBM after RT.

Phase II trial of erlotinib with temozolomide and radiation in patients with newly diagnosed glioblastoma multiforme

Approximately 40-50% of glioblastomas (GBM) overexpress epidermal growth factor receptor (EGFR). Erlotinib is a specific and potent EGFR tyrosine kinase inhibitor active against refractory GBM. Patients with non-small cell lung cancer and > or =grade 2 erlotinib-induced rash have improved survival. This phase 2 study assessed the efficacy and safety of concurrent radiation therapy (RT) and temozolomide with pharmacodynamic dose escalation of erlotinib in patients with newly diagnosed GBM. Patients received RT 60 Gy in 30 fractions with concurrent temozolomide 75 mg/m(2)/day x 42 days, followed in four weeks by temozolomide 150-200 mg/m(2)/day x 5, every 28 days for 12 cycles. Patients received erlotinib, 50 mg/day and increased by 50 mg/day every 2 weeks until the occurrence of grade 2 rash or to a maximum dose of 150 mg/day, from day 1 until disease progression. Twenty-seven patients were treated in this study. Twenty-two (81%) patients came off study for progressive disease (18 [67%]) or adverse events (4 [15%]). Eighteen patients (67%) have died. Median progression-free survival was 2.8 months, and the median overall survival was 8.6 months. Five patients remain on study with a median follow-up of 16 months. Grade 3/4 toxicities included thrombocytopenia, anemia, lymphopenia, fatigue, and febrile neutropenia. There were four deaths on study, three definitely treatment-related; therefore, the trial was terminated after accrual of 27 of 30 planned patients. Erlotinib co administered with RT and temozolomide was not efficacious and had an unacceptable toxicity.

Molecularly targeted therapies for malignant glioma: rationale for combinatorial strategies

Median survival of patients with malignant glioma (MG) from time of diagnosis is approximately 1 year, despite surgery, irradiation and conventional chemotherapy. Improving patient outcome relies on our ability to develop more effective therapies that are directed against the unique molecular aberrations within a patient's tumor. Such molecularly targeted therapies may provide novel treatments that are more effective than conventional chemotherapeutics. Recently developed therapeutic strategies have focused on targeting several core glioma signaling pathways, including pathways mediated by growth-factors, PI3K/Akt/PTEN/mTOR, Ras/Raf/MEK/MAPK and other vital pathways. However, given the molecular diversity, heterogeneity and diverging and converging signaling pathways associated with MG, it is unlikely that any single agent will have efficacy in more than a subset of tumors. Overcoming these therapeutic barriers will require multiple agents that can simultaneously inhibit these processes, providing a rationale for combination therapies. This review summarizes the currently implemented single-agent and combination molecularly targeted therapies for MG.

Combination therapy for malignant glioma based on PTEN status

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a central regulator of cell proliferation, migration, tumor growth, survival, angiogenesis and metabolism, contributing to the malignant phenotype of gliomas. Trials using targeted therapeutics against growth factor receptors and downstream signal mediators of the PI3K pathway have demonstrated only modest clinical benefit. Although recent clinical data suggests that malignant gliomas with PTEN are more likely to respond to EGF receptor inhibitors, gliomas have multiple concomitantly activated pathways, making them highly resistant to single-targeted therapy. This review discusses the importance of the PI3K pathway in glioma, the potential role of PTEN status in directing specific therapies, discusses clinical trial development of drug combinations to treat malignant gliomas and offers strategies for trial design that will be necessary to fully understand the successes and failures of current approaches to glioma therapy.

Phase I/II trial of hyperfractionated concomitant boost proton radiotherapy for supratentorial glioblastoma multiforme

PURPOSE

To evaluate the safety and efficacy of postoperative hyperfractionated concomitant boost proton radiotherapy with nimustine hydrochloride for supratentorial glioblastoma multiforme (GBM).

METHODS AND MATERIALS

Twenty patients with histologically confirmed supratentorial GBM met the following criteria: (1) a Karnofsky performance status of >or=60; (2) the diameter of the enhanced area before radiotherapy was <or=40 cm; and (3) the enhanced area did not extend to the brain stem, hypothalamus, or thalamus. Magnetic resonance imaging (MRI) T(2)-weighted high area (clinical tumor volume 3 [CTV3]) was treated by x-ray radiotherapy in the morning (50.4 Gy in 28 fractions). More than 6 hours later, 250 MeV proton beams were delivered to the enhanced area plus a 10-mm margin (CTV2) in the first half of the protocol (23.1 GyE in 14 fractions) and to the enhanced volume (CTV1) in the latter half (23.1 GyE in 14 fraction). The total dose to the CTV1 was 96.6 GyE. Nimustine hydrochloride (80 mg/m2) was administered during the first and fourth weeks.

RESULTS

Acute toxicity was mainly hematologic and was controllable. Late radiation necrosis and leukoencephalopathy were each seen in one patient. The overall survival rates after 1 and 2 years were 71.1% and 45.3%, respectively. The median survival period was 21.6 months. The 1- and 2-year progression-free survival rates were 45.0% and 15.5%, respectively. The median MRI change-free survival was 11.2 months.

CONCLUSIONS

Hyperfractionated concomitant boost proton radiotherapy (96.6 GyE in 56 fractions) for GBM was tolerable and beneficial if the target size was well considered. Further studies are warranted to pursue the possibility of controlling border region recurrences.

Phase 2 trial of erlotinib plus sirolimus in adults with recurrent glioblastoma

We evaluated the anti-tumor activity and safety of erlotinib, a receptor tyrosine kinase inhibitor of the epidermal growth factor receptor, plus sirolimus, an inhibitor of the mammalian target of rapamycin, among patients with recurrent glioblastoma (GBM) in a phase 2, open-label, single-arm trial. Thirty-two patients received daily erlotinib and sirolimus. The doses of erlotinib and sirolimus were 150 mg and 5 mg for patients not on concurrent CYP3A-inducing anti-epileptics (EIAEDS), and 450 mg and 10 mg for patients on EIAEDS. Evaluations were performed every two months. The primary endpoint was 6-month progression-free survival and secondary endpoints included safety and overall survival. Archival tumor samples were assessed for EGFR, EGFRvIII, PTEN, pAKT and pS6. Enrolled patients were heavily pre-treated including 53% who had received three or more prior chemotherapy agents and 28% who had received prior bevacizumab therapy. The most common grade > or = 2 adverse events were rash (59%), mucositis (34%) and diarrhea (31%). Grade 3 or higher events were rare. Best radiographic response included stable disease in 15 patients (47%); no patients achieved either a CR or PR. The estimated 6-month progression-free survival was 3.1% for all patients. Progression-free survival was better for patients not on EIAEDs (P = 0.03). Tumor markers failed to show an association with PFS except for increased pAKT expression which achieved borderline significance (P = 0.045). Although neither rash nor diarrhea had an association with outcome, hyperlipidemia was associated with longer PFS (P = 0.029). Erlotinib plus sirolimus was well tolerated but had negligible activity among unselected recurrent GBM patients. (ClinicalTrials.gov number: NCT0062243).

Molecularly targeted therapies for malignant gliomas

This review critically evaluates current knowledge of molecularly targeted therapies of malignant gliomas.Various molecularly targeted single-agent therapies, including targeted therapies of growth and survival, have been evaluated in clinical trials but have failed to demonstrate a significant survival benefit compared with standard treatment regimens. The efficacy of multitargeted kinase inhibitors or combinations of single-targeted kinase inhibitors is a promising strategy, but requires additional clinical evaluation before definitive conclusions can be made. Important areas for further research include the assessment of serum or tissue biomarkers, the elucidation of prognostic molecular markers, and the determination of whether the mechanism of action of a drug is appropriate to the genetic alterations observed within individual tumors.

Targeted therapy in the treatment of malignant gliomas

Malignant gliomas are invasive tumors with the potential to progress through current available therapies. These tumors are characterized by a number of abnormalities in molecular signaling that play roles in tumorigenesis, spread, and survival. These pathways are being actively investigated in both the pre-clinical and clinical settings as potential targets in the treatment of malignant gliomas. We will review many of the therapies that target the cancer cell, including the epidermal growth factor receptor, mammalian target of rapamycin, histone deacetylase, and farnesyl transferase. In addition, we will discuss strategies that target the extracellular matrix in which these cells reside as well as angiogenesis, a process emerging as central to tumor development and growth. Finally, we will briefly touch on the role of neural stem cells as both potential targets as well as delivery vectors for other therapies. Interdependence between these varied pathways, both in maintaining health and in causing disease, is clear. Thus, attempts to easily classify some targeted therapies are problematic.

Using in vivo biopanning for the development of radiation-guided drug delivery systems

This chapter illustrates our protocol for in vivo biopanning using T7 bacteriophage libraries for the purpose of selecting recombinant peptides for the tumor-specific delivery of radiosensitizers to radiation-inducible antigens within tumor neovasculature. Our goal is to discover peptides binding within tumor vascular endothelium of irradiated tumors. We have previously demonstrated that tumor irradiation increases the spectrum of antigenic targets for drug delivery. To identify candidate peptides with the ability to bind radiation-induced antigens, we inject the phage peptide library intravenously into mice bearing irradiated GL261 and Lewis lung carcinoma (LLC) hind limb tumors. Phage are recovered from excised tumors, amplified, and readministered to mouse-bearing tumors for six total rounds. At least 50 bacterial colonies are selected from each of the tumor types, and prioritized. This prioritization is based on their relative concentrations in tumor versus normal tissues, and then assessment of dominant phage present in both tumor types. These phage are amplified, and the gene sequences determined to deduce the recombinant peptide product. Further prioritization is performed by fluorescence labeling of the selected phage, and injection into irradiated and mock-irradiated tumor-bearing mice for evaluation of in vivo targeting of the candidate phage/peptides.

Phase II study of erlotinib plus temozolomide during and after radiation therapy in patients with newly diagnosed glioblastoma multiforme or gliosarcoma

PURPOSE

This open-label, prospective, single-arm, phase II study combined erlotinib with radiation therapy (XRT) and temozolomide to treat glioblastoma multiforme (GBM) and gliosarcoma. The objectives were to determine efficacy of this treatment as measured by survival and to explore the relationship between molecular markers and treatment response.

PATIENTS AND METHODS

Sixty-five eligible adults with newly diagnosed GBM or gliosarcoma were enrolled. We intended to treat patients not currently treated with enzyme-inducing antiepileptic drugs (EIAEDs) with 100 mg/d of erlotinib during XRT and 150 mg/d after XRT. Patients receiving EIAEDs were to receive 200 mg/d of erlotinib during XRT and 300 mg/d after XRT. After XRT, the erlotinib dose was escalated until patients developed tolerable grade 2 rash or until the maximum allowed dose was reached. All patients received temozolomide during and after XRT. Molecular markers of epidermal growth factor receptor (EGFR), EGFRvIII, phosphatase and tensin homolog (PTEN), and methylation status of the promotor region of the MGMT gene were analyzed from tumor tissue. Survival was compared with outcomes from two historical phase II trials.

RESULTS

Median survival was 19.3 months in the current study and 14.1 months in the combined historical control studies, with a hazard ratio for survival (treated/control) of 0.64 (95% CI, 0.45 to 0.91). Treatment was well tolerated. There was a strong positive correlation between MGMT promotor methylation and survival, as well as an association between MGMT promotor-methylated tumors and PTEN positivity shown by immunohistochemistry with improved survival.

CONCLUSION

Patients treated with the combination of erlotinib and temozolomide during and following radiotherapy had better survival than historical controls. Additional studies are warranted.

Phase I/II trial of erlotinib and temozolomide with radiation therapy in the treatment of newly diagnosed glioblastoma multiforme: North Central Cancer Treatment Group Study N0177

PURPOSE

Epidermal growth factor receptor (EGFR) amplification in glioblastoma multiforme (GBM) is a common occurrence and is associated with treatment resistance. Erlotinib, a selective EGFR inhibitor, was combined with temozolomide (TMZ) and radiotherapy (RT) in a phase I/II trial.

PATIENTS AND METHODS

Adults not taking enzyme-inducing anticonvulsants after resection or biopsy of GBM were treated with erlotinib (150 mg daily) until progression. Erlotinib was delivered alone for 1 week, then concurrently with TMZ (75 mg mg/m(2) daily) and RT (60 Gy), and finally, concurrently with up to six cycles of adjuvant TMZ (200 mg/m(2) daily for 5 days every 28 days). The primary end point was survival at 1 year.

RESULTS

Ninety-seven eligible patients were accrued with a median follow-up time of 22.2 months. By definition, the primary end point was successfully met with a median survival time of 15.3 months. However, there was no sign of benefit in overall survival when comparing N0177 with the RT/TMZ arm of the European Organisation for Research and Treatment of Cancer/National Cancer Institute of Canada trial 26981/22981 (recursive partitioning analysis [RPA] class III, 19 v 21 months; RPA class IV, 16 v 16 months; RPA class V, 8 v 10 months, respectively). Presence of diarrhea, rash, and EGFRvIII, p53, phosphatase and tensin homolog (PTEN), combination EGFR and PTEN, and EGFR amplification status were not predictive (P > .05) of survival.

CONCLUSION

Although the primary end point was successfully met using nitrosourea-based (pre-TMZ) chemotherapy era historic controls, there was no sign of benefit compared with TMZ era controls. Analyses of molecular subsets did not reveal cohorts of patients sensitive to erlotinib. TMZ chemotherapy combined with RT resulted in improved outcomes compared with historical controls who received nitrosourea-based chemotherapies.

North Central Cancer Treatment Group--achievements and perspectives

The North Central Cancer Treatment Group (NCCTG) was founded in 1977 as a regional cooperative group to allow cancer patients in the upper Midwest of the United States to gain access to clinical trials in oncology by establishing a network of community oncology practices with one academic research base, the Mayo Clinic. Since then, the NCCTG has grown into an international cooperative group with 43 members in 33 US states and Canada. This article details 30 years of achievements of the NCCTG, including important scientific contributions from disease-specific and treatment modality committees, the cancer control program, patient-reported outcomes and quality-of-life research, and biostatisticians that support the NCCTG's specific aims: to improve the duration and quality of life of cancer patients, to enhance our understanding of the biological consequences of cancer and its treatment, and to improve methods for clinical trial conduct.

EGFR family: structure physiology signalling and therapeutic targets

There are four members of the EGFR family: EGFR, erbB2, erbB3 and erbB4. These receptors form ligand-activated oligomers which regulate intracellular processes via an oligomeric tyrosine kinase scaffold. The receptors are activated when the extracellular domain undergoes a conformational change which facilitates either homo- or hetero-oligomerization with other family members. The absence of one EGFR family member leads to embryonic or early post-natal death due to implantation, central nervous system or cardiac defects. Many mouse models of defective or deficient EGFR family members are available for studying physiology and/or pathology of EGFR family members. Sophisticated antibody and kinase inhibitors which target different family members have been designed, produced. EGFR and erbB2 are frequently activated, over expressed or mutated in many common cancers and the antagonists and/or inhibitors of EGFR and/or erbB2 signalling have already been shown to have therapeutic benefits for cancer patients.

Therapeutic application of noncytotoxic molecular targeted therapy in gliomas: growth factor receptors and angiogenesis inhibitors

Growth factor receptors and angiogenesis play major roles in the oncogenesis of gliomas. Over the last several years, several noncytotoxic molecular targeted therapies have been developed against growth factor receptors and tumor angiogenesis. In gliomas, two main anti-growth factor receptor strategies have been evaluated in phase I/II clinical trials: (a) small molecule tyrosine kinase inhibitors (TKIs) and (b) monoclonal antibodies that target growth factors or growth factor receptors other than vascular endothelial growth factor (VEGF). Up to now, few glioma patients have responded to small TKIs (0%-14%) or monoclonal antibodies (three case reports) delivered as a single agent. Greater doses, combined therapies, as well as the identification of molecular biomarkers predictive of response and resistance are important in order to optimize drug delivery and improve efficacy. Antiangiogenic therapies are promising for the treatment of gliomas. Thalidomide and metronomic chemotherapy were the first antiangiogenic strategies evaluated, but they have shown only modest activity. Recent studies of bevacizumab, an anti-VEGF antibody, and irinotecan, a topoisomerase I inhibitor, have demonstrated a high response rate, suggesting that targeted antiangiogenic therapies may play a significant role in the management of high-grade gliomas in the future. However, the toxicity profiles of these agents are not fully defined and the radiological evaluation of possible tumor response is challenging. Clinical evaluation of several VEGF receptor TKIs is currently ongoing; one of these inhibitors, cediranib, has already demonstrated interesting activity as a single agent. The integrin inhibitor cilengitide represents another promising strategy.