VEGF signaling through VEGFR-2 is the major factor in glioblastoma angiogenesis. CT-322, a pegylated protein engineered from the 10th type III human fibronectin domain, binds the VEGFR-2 extracellular domain with high specificity and affinity to block VEGF-induced VEGFR-2 signaling. This study evaluated CT-322 in an open-label run-in/phase 2 setting to assess its efficacy and safety in recurrent glioblastoma. Eligible patients had 1st, 2nd or 3rd recurrence of glioblastoma with measurable tumor on MRI and no prior anti-angiogenic therapy. The initial CT-322 dose was 1 mg/kg IV weekly, with plans to escalate subsequent patients to 2 mg/kg weekly if tolerated; within each CT-322 dose cohort, patients were randomized to ±irinotecan IV semiweekly. The primary endpoint was 6-month progression-free survival (PFS-6). Sixty-three patients with a median age of 56 were treated, the majority at first recurrence. One-third experienced serious adverse events, of which four were at least possibly related to study treatment (two intracranial hemorrhages and two infusion reactions). Twenty-nine percent of subjects developed treatment-emergent hypertension. The PFS-6 rate in the CT-322 monotherapy groups was 18.6 and 0.0 % in the 1 and 2 mg/kg treatment groups, respectively; results from the 2 mg/kg group indicated that the null hypothesis that PFS-6 ?12 % could not be rejected. The study was terminated prior to reaching the planned enrollment for all treatment groups because data from the completed CT-322 2 mg/kg monotherapy treatment arm revealed insufficient efficacy. Despite biological activity and a tolerable side effect profile, CT-322 failed to meet the prespecified threshold for efficacy in recurrent glioblastoma.
Diffusion-weighted imaging (DWI) has been at the forefront of cancer imaging since the early 2000s. Before its application in clinical oncology, this powerful technique had already achieved widespread recognition due to its utility in the diagnosis of cerebral infarction. Following this initial success, the ability of DWI to detect inherent tissue contrast began to be exploited in the field of oncology. Although the initial oncologic applications for tumor detection and characterization, assessing treatment response, and predicting survival were primarily in the field of neurooncology, the scope of DWI has since broadened to include oncologic imaging of the prostate gland, breast, and liver. Despite its growing success and application, misconceptions about the underlying physical basis of the DWI signal exist among researchers and clinicians alike. In this review, we provide a detailed explanation of the biophysical basis of diffusion contrast, emphasizing the difference between hindered and restricted diffusion, and elucidating how diffusion parameters in tissue are derived from the measurements via the diffusion model. We describe one advanced DWI modeling technique, called restriction spectrum imaging (RSI). This technique offers a more direct in vivo measure of tumor cells, due to its ability to distinguish separable pools of water within tissue based on their intrinsic diffusion characteristics. Using RSI as an example, we then highlight the ability of advanced DWI techniques to address key clinical challenges in neurooncology, including improved tumor conspicuity, distinguishing actual response to therapy from pseudoresponse, and delineation of white matter tracts in regions of peritumoral edema. We also discuss how RSI, combined with new methods for correction of spatial distortions inherent in diffusion MRI scans, may enable more precise spatial targeting of lesions, with implications for radiation oncology and surgical planning. See all articles in this Cancer Research section, "Physics in Cancer Research."
A subset of patients with high-grade glioma and brain metastases who are treated with bevacizumab develop regions of marked and persistent restricted diffusion that do not reflect recurrent tumor. Here, we quantify the degree of restricted diffusion and the relative cerebral blood volume (rCBV) within these regions of bevacizumab-related imaging abnormality (BRIA) in order to facilitate differentiation of these lesions from recurrent tumor. Six patients with high-grade glioma and two patients with brain metastases who developed regions of restricted diffusion after initiation of bevacizumab were included. Six pre-treatment GBM controls were also included. Restriction spectrum imaging (RSI) was used to create diffusion maps which were co-registered with rCBV maps. Within regions of restricted diffusion, mean RSI values and mean rCBV values were calculated for patients with BRIA and for the GBM controls. These values were also calculated for normal-appearing white matter (NAWM). RSI values in regions of restricted diffusion were higher for both BRIA and tumor when compared to NAWM; furthermore RSI values in BRIA were slightly higher than in tumor. Conversely, rCBV values were very low in BRIA-lower than both tumor and NAWM. However, there was only a trend for rCBV values to be higher in tumor than in NAWM. When evaluating areas of restricted diffusion in patients with high-grade glioma or brain metastases treated with bevacizumab, RSI is better able to detect the presence of pathology whereas rCBV is better able to differentiate BRIA from tumor. Thus, combining these tools may help to differentiate necrotic tissue related to bevacizumab treatment from recurrent tumor.
Leptomeningeal metastasis (LM) from solid tumors is typically a late manifestation of systemic cancer with limited survival. Randomized trials comparing single agent intrathecal methotrexate to liposomal cytarabine have shown similar efficacy and tolerability. We hypothesized that combination intrathecal chemotherapy would be a safe and tolerable option in solid tumor LM. We conducted a retrospective cohort study of combination IT chemotherapy in solid tumor LM at a single institution between April 2010 and July 2012. In addition to therapies directed at active systemic disease, each subject received IT liposomal cytarabine plus IT methotrexate with dexamethasone premedication. Patient characteristics, survival outcomes and toxicities were determined by systematic chart review. Thirty subjects were treated during the study period. The most common cancer types were breast 15 (50 %), glioblastoma 6 (20 %), and lung 5 (17 %). Cytologic clearance was achieved in 6 (33 %). Median non-glioblastoma overall survival was 30.2 weeks (n = 18; range 3.9-73.4), and did not differ significantly by tumor type. Median time to neurologic progression was 7 weeks (n = 8; range 0.9-57), with 10 subjects (56 %) experiencing death from systemic disease without progression of LM. Age less than 60 was associated with longer overall survival (p = 0.01). Six (21 %) experienced grade III toxicities during treatment, most commonly meningitis 2 (7 %). Combination IT chemotherapy was feasible in this small retrospective cohort. Prospective evaluation is necessary to determine tolerability, the impact on quality of life and neurocognitive outcomes or any survival benefit when compared to single agent IT chemotherapy.
Imaging in neuroscience has been dramatically impacted by the advent of multiphoton microscopy. Multiphoton-excited fluorescence (MPF) in combination with endogenous fluorophores or labeling by fluorescent molecules has proven to be particularly powerful. However, endogenous fluorescence is limited to relatively few molecular species, and practical labeling schemes do not exist for many classes of molecules. Coherent Raman scattering (CRS) techniques, including coherent anti-Stokes Raman scattering and stimulated Raman scattering, allow imaging without the need for staining or fluorescent labeling. Such label-free imaging is desirable in biomedical research, because labeling often perturbs the function of small metabolite and drug molecules and may be too toxic to use in vivo. CRS techniques have similar imaging parameters to MPF, making use of pulsed near-infrared lasers to deliver high-sensitivity, high spatial resolution in three dimensions and rapid image acquisition. In this introduction, we will discuss the basic principles of CRS imaging, present the instrumentation requirements for high-speed CRS imaging, and show an example of imaging brain tumors and healthy tissue based on their intrinsic vibrational signatures. This discussion is intended to introduce the benefits and tradeoffs associated with different CRS techniques and show one example of the powerful capabilities of label-free chemical imaging.
There is a great interest in targeting and selective ablation of populations of circulating cells for research or therapeutic purposes. Red blood cells (RBCs) are readily available and fully biocompatible long-circulating intravascular carriers (natural life is 120days) that are amenable to chemical modifications, drug loading and reinjection. Here we demonstrate that using our previously described lipophilic ligand painting strategy, red blood cells (RBCs) could be in one step converted into targeted entities that selectively seek and bind various cells in vitro and in vivo. In vitro, RBCs modified with lipophilic anti-EpCAM or anti-CD45 antibodies efficiently bound to cancer cells and leukocytes, forming characteristic rosettes. In vivo, intravenously injected RBCs painted with anti-CD45 antibody immediately associated with CD45 positive cells in blood, forming RBC-leukocyte rosettes. Moreover, anti-CD45-modified RBCs, but not the same amount of anti-CD45 antibody or anti-CD45-lipid conjugate (1-2?g/mouse), depleted over 50% of CD45+ leukocytes from circulation, with main clearance organs of leukocytes being liver and spleen with no visible deposition in kidneys and lungs. Anti-CD20 (Rituximab)-painted RBCs efficiently (over 90%) depleted CD19+/CD20+/CD45+ human lymphoma cells in mantle cell lymphoma (MCL) JeKo-1 model, while the same amount of rituximab-lipid (2?g/mouse) was much less efficient in lymphoma cell depletion. Treatment of MCL mice with rituximab-modified RBCs carrying only 2?g of the antibody resulted in a significant prolongation of survival as compared to the same amount of antibody-lipid control. Lipophilic ligand-painted RBCs is a novel tool that can be utilized for targeting blood borne cells for experimental immunology and drug delivery applications.
Glioblastoma (GBM) is an aggressive disease associated with poor survival. It is essential to account for the complexity of GBM biology to improve diagnostic and therapeutic strategies. This complexity is best represented by the increasing amounts of profiling ("omics") data available due to advances in biotechnology. The challenge of integrating these vast genomic and proteomic data can be addressed by a comprehensive systems modeling approach.
Glioblastoma (GBM) is a therapeutic challenge, associated with high mortality. More effective GBM therapeutic options are urgently needed. Hence, we screened a large multi-class drug panel comprising the NIH clinical collection (NCC) that includes 446 FDA-approved drugs, with the goal of identifying new GBM therapeutics for rapid entry into clinical trials for GBM.
Primary and secondary brain cancers are highly treatment resistant, and their marked angiogenesis attracts interest as a potential therapeutic target. Recent observations reveal that the microvascular endothelium of primary high-grade gliomas expresses prostate specific membrane antigen (PSMA). Breast cancers express PSMA and they frequently form secondary brain tumors. Hence we report here our pilot study addressing the feasibility of PSMA targeting in brain and metastatic breast tumors, by examining PSMA levels in all glioma grades (19 patients) and in breast cancer brain metastases (5 patients).
The coagulation protease cascade plays the central requisite role in initiation of arterial atherothrombosis. However, the relative participation of the extrinsic as compared to the intrinsic pathway is incompletely resolved. We have investigated in vivo the relative importance of the extrinsic and intrinsic pathways to define which is more essential to atherothrombosis and therefore the preferable prophylactic therapeutic target. We further addressed which type of plaque associated macrophage population is associated with the thrombotic propensity of atherosclerotic plaques.
Despite recent scientific advances in the understanding of the biology of malignant gliomas, there has been little change in the overall survival for this devastating disease. New and innovative treatments are under constant investigation. Starting in the 1990s, there was an interest in using viral therapeutics for the treatment of malignant gliomas. Multiple strategies were pursued, including oncolytic viral therapy, enzyme/pro-drug combinations and gene transfer with viral vectors. Multiple Phase I and II trials demonstrated the safety of these techniques, but clinically showed limited efficacy. However, this led to a better understanding of the pitfalls of viral therapy and encouraged the development of new approaches and improved delivery methods. Here we review the prior and ongoing clinical trials of viral therapy for gliomas, and discuss how novel strategies are currently being utilized in clinical trials.
Glioblastoma (GBM) is the most common brain cancer and is highly lethal in both adults and children. 2-methoxyestradiol (2ME2) is a microtubule inhibitor that potently inhibits HIF1?, GBM angiogenesis and tumor growth in preclinical models. In patients, 2ME2 exhibits low toxicity and promising but inconsistent efficacy. Given its preclinical potency and its tolerability in patients, we sought to determine whether 2ME2 therapy could be enhanced by addressing resistance via combination therapy, and with biomarkers to identify responsive glioma subgroups. We demonstrate that the PTEN-PI3K axis regulates HIF1? in glioma models. We utilized isogenic-pairs of glioma cell lines, deficient in PTEN or stably reconstituted with PTEN, to determine the role of PTEN in 2ME2 sensitivity in vitro and in vivo. Chou-Talalay synergy studies reveal significant synergy when a pan-PI3K inhibitor is combined with 2ME2. This synergistic activity was correlated with a synergistic suppression of HIF1? accumulation under hypoxic conditions in glioma models. In vivo, 2ME2 markedly inhibited tumor-induced angiogenesis and significantly reduced tumor growth only in a PTEN reconstituted GBM models in both subcutaneous and orthotopic intracranial mouse models. Collectively, these results: (1) suggest that PTEN status predicts sensitivity to 2ME2 and (2) justify exploration of 2ME2 combined with pan-PI3K inhibitors for the treatment of this intractable brain cancer.
Drug transit through the blood-brain barrier (BBB) is essential for therapeutic responses in malignant glioma. Conventional methods for assessment of BBB penetrance require synthesis of isotopically labeled drug derivatives. Here, we report a new methodology using matrix assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) to visualize drug penetration in brain tissue without molecular labeling. In studies summarized here, we first validate heme as a simple and robust MALDI MSI marker for the lumen of blood vessels in the brain. We go on to provide three examples of how MALDI MSI can provide chemical and biological insights into BBB penetrance and metabolism of small molecule signal transduction inhibitors in the brain - insights that would be difficult or impossible to extract by use of radiolabeled compounds.
Scavenger receptors (SRs) are molecular pattern recognition receptors that have been shown to mediate opsonin-independent uptake of therapeutic and imaging nanoparticles, underlying the importance of SRs in nanomedicine. Unlike pathogens, engineered nanomaterials offer great flexibility in control of surface properties, allowing addressing specific questions regarding the molecular mechanisms of nanoparticle recognition. Recently, we showed that SR-type AI/II mediates opsonin-independent internalization of dextran superparamagnetic iron oxide (SPIO) nanoparticles via positively charged extracellular collagen-like domain. To understand the mechanism of opsonin-independent SPIO recognition, we tested the binding and uptake of nanoparticles with different surface coatings by SR-AI. SPIO coated with 10 kDa dextran was efficiently recognized and taken up by SR-AI transfected cells and J774 macrophages, while SPIO with 20 kDa dextran coating or cross-linked dextran hydrogel avoided the binding and uptake. Nanoparticle negative charge density and zeta-potential did not correlate with SR-AI binding/uptake efficiency. Additional experiments and computer modeling revealed that recognition of the iron oxide crystalline core by the positively charged collagen-like domain of SR-AI is sterically hindered by surface polymer coating. Importantly, the modeling revealed a strong complementarity between the surface Fe-OH groups of the magnetite crystal and the charged lysines of the collagen-like domain of SR-AI, suggesting a specific recognition of SPIO crystalline surface. These data provide an insight into the molecular recognition of nanocrystals by innate immunity receptors and the mechanisms whereby polymer coatings promote immune evasion.
To retrospectively assess the utility of (18)F fluorodeoxyglucose (FDG) positron emission tomography (PET) images of standardized uptake values corrected for blood glucose (SUV(gluc)), and to compare this to various quantitative methods to identify the presence or absence of high grade malignancy.
Red blood cells (RBCs) attract significant interest as carriers of biomolecules, drugs, and nanoparticles. In this regard, versatile technologies to attach molecules and ligands to the RBC surface are of great importance. Reported here is a fast and efficient surface painting strategy to attach ligands to the surface of RBCs, and the factors that control the stability and circulation properties of the modified RBCs in vivo. Distearoyl phosphatidylethanolamine anchor-conjugated immunoglobulin (IgG) efficiently incorporates in the RBC membrane following 15-30 min incubation. The optimized RBCs show prolonged circulation in vivo (70% of the injected dose after 48 h) and efficient retention of IgG in the membrane with terminal half-life of 73 h. The IgG construct is gradually lost from the RBCs mainly due to the transfer to plasma components, liver endothelial cells, and Kupffer cells. The ligand retention efficiency is partially dictated by ligand type, anchor type, and ligand concentration in the membrane, while RBC half-life is determined by initial concentration of the ligand in the membrane and presence of PEG linker between the ligand and the anchor. This work provides important guidance for non-covalent surface painting of RBCs as well as other types of blood borne cells for in vivo therapeutic and targeting applications.
A 47-year-old white male with a history of uveitis, hypercalcemia and nephrolithiasis presented with acute onset partial seizure. On exam he had decreased sensation to light touch on his left lower extremity. A Brain MRI revealed a right frontal mass, which was initially thought to be a metastatic lesion or a primary brain tumor. However, biopsy of the lesion revealed it to be a non-caseating granulomatous lesion consistent with neurosarcoidosis.
Identifying physical interactions between proteins and other molecules is a critical aspect of biological analysis. Here we describe PLATO, an in vitro method for mapping such interactions by affinity enrichment of a library of full-length open reading frames displayed on ribosomes, followed by massively parallel analysis using DNA sequencing. We demonstrate the broad utility of the method for human proteins by identifying known and previously unidentified interacting partners of LYN kinase, patient autoantibodies, and the small-molecules gefitinib and dasatinib.
Circulating tumor cells (CTCs) are exfoliated at various stages of cancer, and could provide invaluable information for the diagnosis and prognosis of cancers. There is an urgent need for the development of cost-efficient and scalable technologies for rare CTC enrichment from blood. Here we report a novel method for isolation of rare tumor cells from excess of blood cells using gas-filled buoyant immuno-microbubbles (MBs). MBs were prepared by emulsification of perfluorocarbon gas in phospholipids and decorated with anti-epithelial cell adhesion molecule (EpCAM) antibody. EpCAM-targeted MBs efficiently (85%) and rapidly (within 15 minutes) bound to various epithelial tumor cells suspended in cell medium. EpCAM-targeted MBs efficiently (88%) isolated frequent tumor cells that were spiked at 100,000 cells/ml into plasma-depleted blood. Anti-EpCAM MBs efficiently (>77%) isolated rare mouse breast 4T1, human prostate PC-3 and pancreatic cancer BxPC-3 cells spiked into 1, 3 and 7 ml (respectively) of plasma-depleted blood. Using EpCAM targeted MBs CTCs from metastatic cancer patients were isolated, suggesting that this technique could be developed into a valuable clinical tool for isolation, enumeration and analysis of rare cells.
There is currently no standard therapy for recurrent or chemotherapy-refractory central nervous system lymphoma (CNSL). Pemetrexed has been reported to have activity in patients with primary CNSL (PCNSL). The use of pemetrexed in secondary CNS lymphoma (SCNSL) has not previously been reported. Here we retrospectively review the outcomes and toxicities of standard and modified doses of pemetrexed as salvage therapy in 18 PCNSL and 12 SCNSL patients. The overall response rate for PCNSL patients was 64.7 %, all of whom achieved a complete response (CR). The median progression-free survival (PFS) was 5.8 months. For the SCNSL patients, RR was 58.3 % with 2 CR (16.7 %); the median PFS was 2.5 months. Grade ?3 adverse events included leukopenia in 5 patients (16.7 %), neutropenia in 1 patient (3.3 %), and fatigue in 3 patients (10.0 %). 3 patients died while on treatment, 2 due to infections and 1 due to pulmonary embolism. Our results indicate that pemetrexed has activity as salvage therapy in recurrent PCNSL, even with modified dosing, but outcomes trend towards less favorable in SCNSL.
With 5.9 billion reported users, mobile phones constitute a new, ubiquitous and rapidly growing exposure worldwide. Mobile phones are two-way microwave radios that also emit low levels of electromagnetic radiation. Inconsistent results have been published on potential risks of brain tumors tied with mobile phone use as a result of important methodological differences in study design and statistical power. Some studies have examined mobile phone users for periods of time that are too short to detect an increased risk of brain cancer, while others have misclassified exposures by placing those with exposures to microwave radiation from cordless phones in the control group, or failing to attribute such exposures in the cases. In 2011, the World Health Organization, International Agency for Research on Cancer (IARC) advised that electromagnetic radiation from mobile phone and other wireless devices constitutes a "possible human carcinogen," 2B. Recent analyses not considered in the IARC review that take into account these methodological shortcomings from a number of authors find that brain tumor risk is significantly elevated for those who have used mobile phones for at least a decade. Studies carried out in Sweden indicate that those who begin using either cordless or mobile phones regularly before age 20 have greater than a fourfold increased risk of ipsilateral glioma. Given that treatment for a single case of brain cancer can cost between $100,000 for radiation therapy alone and up to $1 million depending on drug costs, resources to address this illness are already in short supply and not universally available in either developing or developed countries. Significant additional shortages in oncology services are expected at the current growth of cancer. No other environmental carcinogen has produced evidence of an increased risk in just one decade. Empirical data have shown a difference in the dielectric properties of tissues as a function of age, mostly due to the higher water content in childrens tissues. High resolution computerized models based on human imaging data suggest that children are indeed more susceptible to the effects of EMF exposure at microwave frequencies. If the increased brain cancer risk found in young users in these recent studies does apply at the global level, the gap between supply and demand for oncology services will continue to widen. Many nations, phone manufacturers, and expert groups, advise prevention in light of these concerns by taking the simple precaution of "distance" to minimize exposures to the brain and body. We note than brain cancer is the proverbial "tip of the iceberg"; the rest of the body is also showing effects other than cancers.
Recent advances in the ability to efficiently characterize tumor genomes is enabling targeted drug development, which requires rigorous biomarker-based patient selection to increase effectiveness. Consequently, representative DNA biomarkers become equally important in pre-clinical studies. However, it is still unclear how well these markers are maintained between the primary tumor and the patient-derived tumor models. Here, we report the comprehensive identification of somatic coding mutations and copy number aberrations in four glioblastoma (GBM) primary tumors and their matched pre-clinical models: serum-free neurospheres, adherent cell cultures, and mouse xenografts. We developed innovative methods to improve the data quality and allow a strict comparison of matched tumor samples. Our analysis identifies known GBM mutations altering PTEN and TP53 genes, and new actionable mutations such as the loss of PIK3R1, and reveals clear patient-to-patient differences. In contrast, for each patient, we do not observe any significant remodeling of the mutational profile between primary to model tumors and the few discrepancies can be attributed to stochastic errors or differences in sample purity. Similarly, we observe ?96% primary-to-model concordance in copy number calls in the high-cellularity samples. In contrast to previous reports based on gene expression profiles, we do not observe significant differences at the DNA level between in vitro compared to in vivo models. This study suggests, at a remarkable resolution, the genome-wide conservation of a patients tumor genetics in various pre-clinical models, and therefore supports their use for the development and testing of personalized targeted therapies.
Glioblastoma cells secrete extra-cellular vesicles (EVs) containing microRNAs (miRNAs). Analysis of these EV miRNAs in the bio-fluids of afflicted patients represents a potential platform for biomarker development. However, the analytic algorithm for quantitative assessment of EV miRNA remains under-developed. Here, we demonstrate that the reference transcripts commonly used for quantitative PCR (including GAPDH, 18S rRNA, and hsa-miR-103) were unreliable for assessing EV miRNA. In this context, we quantitated EV miRNA in absolute terms and normalized this value to the input EV number. Using this method, we examined the abundance of miR-21, a highly over-expressed miRNA in glioblastomas, in EVs. In a panel of glioblastoma cell lines, the cellular levels of miR-21 correlated with EV miR-21 levels (p<0.05), suggesting that glioblastoma cells actively secrete EVs containing miR-21. Consistent with this hypothesis, the CSF EV miR-21 levels of glioblastoma patients (n=13) were, on average, ten-fold higher than levels in EVs isolated from the CSF of non-oncologic patients (n=13, p<0.001). Notably, none of the glioblastoma CSF harbored EV miR-21 level below 0.25 copies per EV in this cohort. Using this cut-off value, we were able to prospectively distinguish CSF derived from glioblastoma and non-oncologic patients in an independent cohort of twenty-nine patients (Sensitivity=87%; Specificity=93%; AUC=0.91, p<0.01). Our results suggest that CSF EV miRNA analysis of miR-21 may serve as a platform for glioblastoma biomarker development.
Staurosporine (STS) is a potent pan-kinase inhibitor with marked activity against several chemotherapy-resistant tumor types in vitro. The translational progress of this compound has been hindered by poor pharmacokinetics and toxicity. We sought to determine whether liposomal encapsulation of STS would enhance antitumor efficacy and reduce toxicity, thereby supporting the feasibility of further preclinical development. We developed a novel reverse pH gradient liposomal loading method for STS, with an optimal buffer type and drug-to-lipid ratio. Our approach produced 70% loading efficiency with good retention, and we provide, for the first time, an assessment of the in vivo antitumor activity of STS. A low intravenous dose (0.8 mg/kg) inhibited U87 tumors in a murine flank model. Biodistribution showed preferential tumor accumulation, and body weight data, a sensitive index of STS toxicity, was unaffected by liposomal STS, but did decline with the free compound. In vitro experiments revealed that liposomal STS blocked Akt phosphorylation, induced poly(ADP-ribose) polymerase cleavage, and produced cell death via apoptosis. This study provides a basis to explore further the feasibility of liposomally encapsulated STS, and potentially related compounds for the management of resistant solid tumors.
Importance: With the increasing use of antiangiogenic agents in the treatment of high-grade gliomas, we are becoming increasingly aware of distinctive imaging findings seen in a subset of patients treated with these agents. Of particular interest is the development of regions of marked and persistent restricted diffusion. We describe a case with histopathologic validation, confirming that this region of restricted diffusion represents necrosis and not viable tumor. Observations: We present a case report of a 52-year-old man with GBM treated with temozolomide, radiation, and concurrent bevacizumab following gross total resection. The patient underwent sequential MRIs which included restriction-spectrum imaging (RSI), an advanced diffusion-weighted imaging (DWI) technique, and MR perfusion. Following surgery, the patient developed an area of restricted diffusion on RSI which became larger and more confluent over the next several months. Marked signal intensity on RSI and very low cerebral blood volume (CBV) on MR perfusion led us to favor bevacizumab-related necrosis over recurrent tumor. Subsequent histopathologic evaluation confirmed coagulative necrosis. Conclusion and Relevance: Our report increases the number of pathologically proven cases of bevacizumab-related necrosis in the literature from three to four. Furthermore, our case demonstrates this phenomenon on RSI, which has been shown to have good sensitivity to restricted diffusion.
Central nervous system (CNS) metastasis from breast cancer may be characterized as either parenchymal brain metastasis (BM) or leptomeningeal (LM) metastasis. BM are much more common (about 80% of all CNS metastases), and have been more extensively studied than LM. CNS metastasis in breast cancer has been associated with reduced overall survival, with the shortest survival generally observed in cases of LM. Here, we review the epidemiology, prognostic factors, diagnostic tools, currently available treatments, and potential future therapies for LM from breast cancer.
Unlike normal tissues, cancers experience profound alterations in protein homeostasis. Powerful innate adaptive mechanisms, especially the transcriptional response regulated by Heat Shock Factor 1 (HSF1), are activated in cancers to enable survival under these stressful conditions. Natural products that further tax these stress responses can overwhelm the ability to cope and could provide leads for the development of new, broadly effective anticancer drugs. To identify compounds that drive the HSF1-dependent stress response, we evaluated over 80,000 natural and synthetic compounds as well as partially purified natural product extracts using a reporter cell line optimized for high-throughput screening. Surprisingly, many of the strongly active compounds identified were natural products representing five diverse chemical classes (limonoids, curvularins, withanolides, celastraloids, and colletofragarones). All of these compounds share the same chemical motif, an ?,?-unsaturated carbonyl functionality, with strong potential for thiol-reactivity. Despite the lack of a priori mechanistic requirements in our primary phenotypic screen, this motif was found to be necessary albeit not sufficient, for both heat-shock activation and inhibition of glioma tumor cell growth. Within the withanolide class, a promising therapeutic index for the compound withaferin A was demonstrated in vivo using a stringent orthotopic human glioma xenograft model in mice. Our findings reveal that diverse organisms elaborate structurally complex thiol-reactive metabolites that act on the stress responses of heterologous organisms including humans. From a chemical biology perspective, they define a robust approach for discovering candidate compounds that target the malignant phenotype by disrupting protein homeostasis.
Glioblastoma (GBM) is a highly malignant brain cancer characterized by uncontrolled cellular proliferation, diffuse infiltration, a tendency for necrosis, significant angiogenesis, intense resistance to apoptosis, and widespread genomic aberrations. Prognosis is poor and treatments are largely palliative, although there are subsets of patients that have prolonged survival. Greater understanding of the tumor biology of GBM has been achieved in the past decade, leading to the prospect of novel targeted therapies and biomarker-based individualization of therapy. The goal of this review is to describe the tumor biology and pathologic features of GBM, guidelines for classification and diagnosis, the current status of prognostic and predictive biomarkers, and the role of the blood-brain barrier in delivering therapy for GBM.
The incorporation of radiotherapy into multimodality treatment plans has led to significant improvements in glioma patient survival. However, local recurrence from glioma resistance to ionizing radiation remains a therapeutic challenge. The tumoricidal effect of radiation therapy is largely attributed to the induction of dsDNA breaks (DSBs). In the past decade, there have been tremendous strides in understanding the molecular mechanisms underlying DSB repair. The identification of gene products required for DSB repair has provided novel therapeutic targets. Recent studies revealed that many US FDA-approved cancer agents inhibit DSB repair by interacting with repair proteins. This article will aim to provide discussion of DSB repair mechanisms to provide molecular targets for radiation sensitization of gliomas and a discussion of FDA-approved cancer therapies that modulate DSB repair to highlight opportunities for combination therapy with radiotherapy for glioma therapy.
Glioblastoma multiforme (GBM) is the most common primary brain tumor of adults and carries a poor prognosis. This study sought to investigate recurrence patterns of GBM treated with temozolomide-based chemoradiation. Records for 31 patients treated for newly diagnosed GBM between 2007 and 2009 were retrospectively analyzed. Ten patients received maximal surgical resection followed by conventionally fractionated radiation (CFR) to a median dose of 60 Gy with concurrent and planned adjuvant temozolomide. Twelve patients were treated with maximal surgical debulking, intracavitary brachytherapy (ICB), and external beam radiation therapy with concurrent and planned adjuvant temozolomide. The remaining 9 patients had unresectable disease and underwent biopsy followed by a hypofractionated course of radiation to a median dose of 60 Gy over 10 fractions. Tumor failure was classified as local, marginal, or distant according to whether the recurrence was completely inside, crossed, or completely outside the 100% isodose line. With a median follow-up of 12.6 months, 5 patients were lost to follow-up, while the remaining 26 patients (100%) developed recurrent disease. The first failures totaled 29 discrete lesions, of which 15 (52%), 6 (21%), and 8 (28%) were local, marginal, and distant failures at median times of 6.8, 10.1, and 7.9 months, respectively. Marginal or distant failure was more likely in ICB patients as compared to CFR patients. While local failure predominated, distant failures were not uncommon, particularly at later time points. As local control of GBM improves, further study is needed to identify and appropriately treat patients susceptible to distant failure.
Recent, studies have shown that Tcf7l2, an important transcription factor in Wnt pathway, plays critical roles in oligodendrocyte development. In this article we report a study showing that Tcf7l2 is under tight regulation during myelin formation. We have found that during early development, Tcf7l2 mRNA appears much earlier than the protein, suggesting a regulation at the translational level. We induced demyelination in a mouse model by a dietary toxin, where remyelination followed after a few weeks, and found that Tcf7l2 protein was expressed specifically during the active remyelination phase. Similarly, in human patients with demyelination diseases, Tcf7l2 protein expression was specifically promoted in regions undergoing active remyelination. During remyelination, Tcf7l2 was only expressed in non-dividing oligodendrocyte precursors and was associated with modest levels of nuclear beta-catenin. We also documented that Tcf7l2 could form protein complex with Olig2, but not with Olig1. Our data showed that during myelin formation, Tcf7l2/beta-catenin is regulated temporally, spatially, and also at levels of expression. These data suggest a key role for Tcf7l2 in myelination/remyelination processes via a tightly controlled activation of Wnt/beta-catenin pathway and the interaction with Olig2.
Meningiomas that arise outside the cranial vault without a dural connection comprise about 1–2% of all meningiomas and are referred to as primary extradural meningiomas (PEMs), intraosseous type 1. When these tumors occur within bone, they may be initially misinterpreted radiologically as a primary bone lesion.We report the case of a 71-year-old woman found to have a right lateral orbital wall mass without dural involvement. Pathology confirmed a PEM and we review the clinical, radiologic, and pathologic features of this case.
Genomic alterations of the epidermal growth factor receptor (EGFR) gene play a crucial role in pathogenesis of glioblastoma multiforme (GBM). By systematic analysis of GBM genomic data, we have identified and characterized a novel exon 27 deletion mutation occurring within the EGFR carboxyl-terminus domain (CTD), in addition to identifying additional examples of previously reported deletion mutations in this region. We show that the GBM-derived EGFR CTD deletion mutants are able to induce cellular transformation in vitro and in vivo in the absence of ligand and receptor autophosphorylation. Treatment with the EGFR-targeted monoclonal antibody, cetuximab, or the small molecule EGFR inhibitor, erlotinib, effectively impaired tumorigenicity of oncogenic EGFR CTD deletion mutants. Cetuximab in particular prolonged the survival of intracranially xenografted mice with oncogenic EGFR CTD deletion mutants, compared with untreated control mice. Therefore, we propose that erlotinib and, especially, cetuximab treatment may be a promising therapeutic strategy in GBM patients harboring EGFR CTD deletion mutants.
Neoplastic meningitis, also known as leptomeningeal metastases, is a complication of various types of cancer that occurs when tumor cells enter the cerebrospinal fluid (CSF), travel along CSF pathways and grow. Treatment options include drug delivery directly into the CNS or systemic administration for targeted action in the CNS. CNS drug delivery is limited by the blood-brain barrier and the blood-CSF barrier. It may be possible to partially overcome this by using high-dose systemic therapy; however, this is done at the possible expense of increased systemic toxicity. Intra-CSF drug delivery bypasses the blood-brain barrier and allows direct access of the chemotherapeutic agent to the CSF. Because neoplastic meningitis occurs in an increasingly large percentage of all cancer patients, it is imperative to optimize drug delivery to the CSF and meninges. Both the pharmacokinetic profile of the chemotherapeutic agent and the site of administration influence therapeutic efficacy. Achieving prolonged therapeutic cytotoxic drug concentrations and even distribution in the CSF will improve efficacy. In this article we summarize data on the efficacy, safety and outcome of high-dose systemic and intra-CSF treatments.
Paragangliomas are rare neuroendocrine tumors of neural crest origin. They are mostly benign, however; malignant tumors with aggressive behavior and distant metastasis can also occur. Intracranial involvement is extremely rare and has been sporadically reported in the literature. Here we report a case who presented with progressive neurologic deficits due to multiple intracranial lesions found to be metastasis from an occult retroperitoneal malignant paraganglioma.
A 45-year-old man with a new diagnosis of low grade glioma was started on an escalating dose of levetiracetam (Lev) for seizure management. He gradually developed intractable nausea/vomiting and a high creatinine concentration due to acute renal failure which was attributed to Lev-induced interstitial nephritis. The medication was changed and his renal function rapidly improved to his baseline.
Quantum dots (QDs) are attracting intense interest as fluorescence labeling agents for biomedical imaging because biocompatible coatings and relatively nontoxic rare earth metal QDs have emerged as possible options. QD photoemissions are bright, of narrow wavelength range, and very stable. We sought to encapsulate QDs within targeted PEGylated liposomes to reduce their propensity for liver uptake and to amplify the already strong QD emission signal. A novel lipid-QD conjugate initialized a process by which lipids in solution coalesced around the QDs. The liposomal structure was confirmed with size measurements, SEM, and IR spectroscopy. PEGylated QD liposomes injected into a xenograft tumor model largely cleared from the body within 24 h. Residual liver labeling was low. Targeted QD liposomes exhibited robust tumor labeling compared with controls. This study highlights the potential of these near IR emitting QD liposomes for preclinical/clinical applications.
Herein, we present an adult case of medulloblastoma who received chemotherapy, radiation therapy and stem cell transplantation, and underwent multiple surgical resections for what were thought to be recurrences; however pathology confirmed a diagnosis of relapsing tumefactive lesions. This phenomenon seems to be a consequence of stem cell transplantation rather than a simple radiation treatment effect.
We tested the use of the small-molecule Inhibitor of Apoptosis Protein (IAP) inhibitor LBW242 in combination with the standard-of-care therapies of irradiation and temozolomide for malignant gliomas. In vitro assays demonstrated that LBW242 enhanced the cytotoxic activity of radiotherapy, and clonogenic assays showed that the combination therapy led to a synergistic anti-glioma effect in multiple cell lines. Neurosphere assays revealed that the combination of radiation and LBW242 led to a pro-apoptotic effect in these glioma-initiating cell-enriched assays, with a corresponding inhibition of primary tumor cell growth. Athymic mice bearing established human malignant glioma tumor xenografts treated with LBW242 plus radiation and temozolomide demonstrated a synergistic suppression of tumor growth. Taken together, these experiments show that the pro-apoptotic and anti-glioma effects of radiotherapy and chemotherapy can be enhanced by the addition of a small-molecule IAP inhibitor. These results are readily translatable to clinical trial and offer the potential for improved treatment outcomes for patients with glioma.
Neoplastic meningitis (NM) is a debilitating and increasingly frequent neurological complication of cancer characterized by infiltration of tumor cells into the leptomeninges and the subarachnoid space. Although NM is rarely curable, combined intrathecal chemotherapy and focal radiation can improve disease-related symptoms and survival. Hydrocephalus occurs in a significant proportion of patients, is associated with poor prognosis and reduced quality of life, and usually precludes the use of intrathecal therapy.
A 45-year-old male presented with subacute onset of a right-sided hemiparesis, right homonymous hemianopsia, and slurred speech. The brain imaging revealed two separate intraparenchymal enhancing lesions. The cerebrospinal fluid rapid plasma reagin and venereal disease research laboratory test were positive and consistent with syphilitic gumma, and the patient responded dramatically to penicillin G. Despite, currently low incidence of syphilis; CNS gummas should be in the differential of mass lesions as they are eminently treatable.
Recurrent intracranial aneurysms can occur after either surgical clipping or endovascular therapy. In this article, we present a consecutive series of 18 patients who underwent individual treatment for recurrent aneurysms after primary coil embolization or surgical clipping. During an 8-year period between May 1997 and December 2005, 18 patients underwent individual treatment for recurrent aneurysms. Clinical data and imaging studies of the patients were analyzed retrospectively. Out of the 18 patients, 13 had recurrent aneurysms located in the anterior circulation, and 5 had aneurysms of the posterior circulation. Treatment consisted of coiling in 16 patients and clipping in two patients. Of the 18 patients, 15 achieved a good or excellent recovery, two were paralyzed, and one died post-treatment. Both the surgical clipping and endovascular embolization for the treatment of recurrent intracranial aneurysms can achieve very good radiological results with low mortality rates. One of the key points for the successful treatment of this kind of lesions is the proper, individual, and interdisciplinary patient selection.
Glucocorticoids have been used for decades in the treatment of brain tumor patients and belong to the most powerful class of agents in reducing tumor-associated edema and minimizing side effects and the risk of encephalopathy in patients undergoing radiation therapy. Unfortunately, corticosteroids are associated with numerous and well-characterized adverse effects, constituting a major challenge in patients requiring long-term application of corticosteroids. Novel antiangiogenic agents, such as bevacizumab (Avastin®), which have been increasingly used in cancer patients, are associated with significant steroid-sparing effects, allowing neuro-oncologists to reduce the overall use of corticosteroids in patients with progressive malignant brain tumors. Recent experimental studies have revealed novel insights into the mechanisms and effects of corticosteroids in cancer patients, including modulation of tumor biology, angiogenesis and steroid-associated neurotoxicity. This article summarizes current concepts of using corticosteroids in brain cancer patients and highlights potential pitfalls in their effects on both tumor and neural progenitor cells.
A 37-year-old female presented with medically intractable complex partial seizures with secondary generalization. She was found to have a dural-based lesion with radiologic features of meningioma. A gross total resection was performed and pathology confirmed a diagnosis of cavernous angioma and she became seizure free after the surgical resection. Cavernous angioma should be considered in differential diagnosis of a dural-based lesion manifesting with refractory seizures.
With advances in genomic profiling and sequencing technology, we are beginning to understand the landscape of the genetic events that accumulated during the neoplastic process. The insights gleamed from these genomic profiling studies with regards to glioblastoma etiology has been particularly satisfying because it cemented the clinical pertinence of major concepts in cancer biology-concepts developed over the past three decades. This article will review how the glioblastoma genomic data set serves as an illustrative platform for the concepts put forward by Hanahan and Weinberg on the cancer phenotype. The picture emerging suggests that most glioblastomas evolve along a multitude of pathways rather than a single defined pathway. In this context, the article will further provide a discussion of the subtypes of glioblastoma as they relate to key principles of developmental neurobiology.
Progressive multifocal leukoencephalopathy (PML) is a severe demyelinating disease of the brain caused by JC virus (JCV). To assess the role of CD4(+) and CD8(+) T-cells against JCV in the clinical outcome of PML and PML in the setting of immune reconstitution inflammatory syndrome (IRIS), we tested gamma interferon (IFN-?) response by enzyme-linked immunosorbent spot (ELISpot) and intracellular cytokine staining (ICS) in 117 subjects, including 66 PML patients with different clinical outcomes. Both assays were concordant and demonstrated that the cellular immune response against JCV is associated with better clinical outcome. PML survivors had an early CD8(+) T-cell response more frequently than PML progressors (100% versus 27.3%; P = 0.001), while only a trend was observed for the early CD4(+) T-cell response between these two groups (80% versus 45.5%; P = 0.18). Although IRIS itself was more frequent in the PML survivor group, there was no difference in IFN-?-producing CD4(+) and CD8(+) T-cells between IRIS and non-IRIS PML patients, suggesting that T-cells expressing other cytokines likely have a role in the immunopathogenesis of IRIS. ELISpot and ICS assays are useful prognostic markers of PML evolution and may help in the clinical management of these patients.
Leptomeningeal metastasis is a devastating complication of the central nervous system in patients with late-stage solid or hematological cancers. Leptomeningeal metastasis results from the multifocal seeding of the leptomeninges by malignant cancer cells. Although central nervous system metastasis usually presents in patients with widely disseminated and progressive late-stage cancer, malignant cells may spread to the cerebrospinal fluid during earlier disease stages in particularly aggressive cancers. Treatment of leptomeningeal metastasis is largely palliative but will often provide stabilization and protection from further neurological deterioration and improve quality of life. There is a need to raise awareness of the impact of leptomeningeal metastases on cancer patients and its known and putative biological basis. Novel diagnostic approaches include identification of biomarkers that may stratify the risk for developing leptomeningeal metastasis. Current therapies can be used more effectively while waiting for advanced treatments to be developed.
MicroRNA (miRNA) expression profiling studies revealed a number of miRNAs dysregulated in the malignant brain tumor glioblastoma. Molecular functions of these miRNAs in gliomagenesis are mainly unknown. We show that inhibition of miR-10b, a miRNA not expressed in human brain and strongly upregulated in both low-grade and high-grade gliomas, reduces glioma cell growth by cell-cycle arrest and apoptosis. These cellular responses are mediated by augmented expression of the direct targets of miR-10b, including BCL2L11/Bim, TFAP2C/AP-2?, CDKN1A/p21, and CDKN2A/p16, which normally protect cells from uncontrolled growth. Analysis of The Cancer Genome Atlas expression data set reveals a strong positive correlation between numerous genes sustaining cellular growth and miR-10b levels in human glioblastomas, while proapoptotic genes anticorrelate with the expression of miR-10b. Furthermore, survival of glioblastoma patients expressing high levels of miR-10 family members is significantly reduced in comparison to patients with low miR-10 levels, indicating that miR-10 may contribute to glioma growth in vivo. Finally, inhibition of miR-10b in a mouse model of human glioma results in significant reduction of tumor growth. Altogether, our experiments validate an important role of miR-10b in gliomagenesis, reveal a novel mechanism of miR-10b-mediated regulation, and suggest the possibility of its future use as a therapeutic target in gliomas.
Glioblastoma Multiforme (GBM), the most common and lethal primary human brain tumor, exhibits multiple molecular aberrations. We report that loss of the transcription factor GATA4, a negative regulator of normal astrocyte proliferation, is a driver in glioma formation and fulfills the hallmarks of a tumor suppressor gene (TSG). Although GATA4 was expressed in normal brain, loss of GATA4 was observed in 94/163 GBM operative samples and was a negative survival prognostic marker. GATA4 loss occurred through promoter hypermethylation or novel somatic mutations. Loss of GATA4 in normal human astrocytes promoted high-grade astrocytoma formation, in cooperation with other relevant genetic alterations such as activated Ras or loss of TP53. Loss of GATA4 with activated Ras in normal astrocytes promoted a progenitor-like phenotype, formation of neurospheres, and the ability to differentiate into astrocytes, neurons, and oligodendrocytes. Re-expression of GATA4 in human GBM cell lines, primary cultures, and brain tumor-initiating cells suppressed tumor growth in vitro and in vivo through direct activation of the cell cycle inhibitor P21(CIP1), independent of TP53. Re-expression of GATA4 also conferred sensitivity of GBM cells to temozolomide, a DNA alkylating agent currently used in GBM therapy. This sensitivity was independent of MGMT (O-6-methylguanine-DNA-methyltransferase), the DNA repair enzyme which is often implicated in temozolomide resistance. Instead, GATA4 reduced expression of APNG (alkylpurine-DNA-N-glycosylase), a DNA repair enzyme which is poorly characterized in GBM-mediated temozolomide resistance. Identification and validation of GATA4 as a TSG and its downstream targets in GBM may yield promising novel therapeutic strategies.
Immune responses targeting self-proteins (autoantigens) can lead to a variety of autoimmune diseases. Identification of these antigens is important for both diagnostic and therapeutic reasons. However, current approaches to characterize autoantigens have, in most cases, met only with limited success. Here we present a synthetic representation of the complete human proteome, the T7 peptidome phage display library (T7-Pep), and demonstrate its application to autoantigen discovery. T7-Pep is composed of >413,000 36-residue, overlapping peptides that cover all open reading frames in the human genome, and can be analyzed using high-throughput DNA sequencing. We developed a phage immunoprecipitation sequencing (PhIP-Seq) methodology to identify known and previously unreported autoantibodies contained in the spinal fluid of three individuals with paraneoplastic neurological syndromes. We also show how T7-Pep can be used more generally to identify peptide-protein interactions, suggesting the broader utility of our approach for proteomic research.
The severity of brain tumor associated seizures often mirror the growth of the underlying tumor, and may be intractable to conventional antiepileptic drugs. We present a patient with intractable seizures in the setting of a low grade glioma who responded dramatically to temozolomide despite minimal radiographic change in tumor size. Temozolomide is an effective treatment for seizure control in patients with brain tumors.
Prostate cancer is rarely associated with leptomeningeal metastasis. An 87-year-old man with a history of prostate cancer presented with leptomeningeal metastasis. He received hormonal therapy with leuprolide. Subsequently, he achieved an impressive response, indicated by a constant fall in his PSA levels and by the stabilization of leptomeningeal disease and clinical improvement. Hormonal therapy may be effective in inducing remission in hormone-sensitive prostate cancer with leptomeningeal metastasis.
We present an 80-year-old lady with a history of ovarian cancer, who manifested with seizure and left upper extremity weakness. The imaging revealed a multilobulated mass within right parietal lobe. She underwent surgical resection and the pathology was compatible with metastasis from ovarian adenocarcinoma. She received a whole brain radiation therapy and she has been in remission for more than 2 years.
Glioblastoma (GBM) is the most malignant brain tumor and is highly resistant to intensive combination therapies and anti-VEGF therapies. To assess the resistance mechanism to anti-VEGF therapy, we examined the vessels of GBMs in tumors that were induced by the transduction of p53(+/-) heterozygous mice with lentiviral vectors containing oncogenes and the marker GFP in the hippocampus of GFAP-Cre recombinase (Cre) mice. We were surprised to observe GFP(+) vascular endothelial cells (ECs). Transplantation of mouse GBM cells revealed that the tumor-derived endothelial cells (TDECs) originated from tumor-initiating cells and did not result from cell fusion of ECs and tumor cells. An in vitro differentiation assay suggested that hypoxia is an important factor in the differentiation of tumor cells to ECs and is independent of VEGF. TDEC formation was not only resistant to an anti-VEGF receptor inhibitor in mouse GBMs but it led to an increase in their frequency. A xenograft model of human GBM spheres from clinical specimens and direct clinical samples from patients with GBM also showed the presence of TDECs. We suggest that the TDEC is an important player in the resistance to anti-VEGF therapy, and hence a potential target for GBM therapy.
Malignant gliomas are highly lethal tumors resistant to current therapies. The standard treatment modality for these tumors, surgical resection followed by radiation therapy and concurrent temozolomide, has demonstrated activity, but development of resistance and disease progression is common. Although oncogenic Ras mutations are uncommon in gliomas, Ras has been found to be constitutively activated through the action of upstream signaling pathways, suggesting that farnesyltransferase inhibitors may show activity against these tumors. We now report the in vitro and orthotopic in vivo results of combination therapy using radiation, temozolomide and lonafarnib (SCH66336), an oral farnesyl transferase inhibitor, in a murine model of glioblastoma. We examined the viability, proliferation, farnesylation of H-Ras, and activation of downstream signaling of combination-treated U87 cells in vitro. Lonafarnib alone or in combination with radiation and temozolomide had limited tumor cell cytotoxicity in vitro although it did demonstrate significant inhibition in tumor cell proliferation. In vivo, lonafarnib alone had a modest ability to inhibit orthotopic U87 tumors, radiation and temozolomide demonstrated better inhibition, while significant anti-tumor activity was found with concurrent lonafarnib, radiation, and temozolomide, with the majority of animals demonstrating a decrease in tumor volume. The use of tumor neurospheres derived from freshly resected adult human glioblastoma tissue was relatively resistant to both temozolomide and radiation therapy. Lonafarnib had a significant inhibitory activity against these neurospheres and could potentate the activity of temozolomide and radiation. These data support the continued research of high grade glioma treatment combinations of farnesyl transferase inhibitors, temozolomide, and radiation therapy.
Magnetic resonance imaging (MRI) is the imaging modality of choice by which to monitor patient gliomas and treatment effects, and has been applied to murine models of glioma. However, a major obstacle to the development of effective glioma therapeutics has been that widely used animal models of glioma have not accurately recapitulated the morphological heterogeneity and invasive nature of this very lethal human cancer. This deficiency is being alleviated somewhat as more representative models are being developed, but there is still a clear need for relevant yet practical models that are well-characterized in terms of their MRI features. Hence we sought to chronicle the MRI profile of a recently developed, comparatively straightforward human tumor stem cell (hTSC) derived glioma model in mice using conventional MRI methods. This model reproduces the salient features of gliomas in humans, including florid neoangiogenesis and aggressive invasion of normal brain. Accordingly, the variable, invasive morphology of hTSC gliomas visualized on MRI duplicated that seen in patients, and it differed considerably from the widely used U87 glioma model that does not invade normal brain. After several weeks of tumor growth the hTSC model exhibited an MRI contrast enhancing phenotype having variable intensity and an irregular shape, which mimicked the heterogeneous appearance observed with human glioma patients. The MRI findings reported here support the use of the hTSC glioma xenograft model combined with MRI, as a test platform for assessing candidate therapeutics for glioma, and for developing novel MR methods.
High-grade gliomas are notoriously insensitive to radiation and genotoxic drugs. Paradoxically, the p53 gene is structurally intact in the majority of these tumors. Resistance to genotoxic modalities in p53-positive gliomas is generally attributed to attenuation of p53 functions by mutations of other components within the p53 signaling axis, such as p14(Arf), MDM2, and ATM, but this explanation is not entirely satisfactory. We show here that the central nervous system (CNS)-restricted transcription factor Olig2 affects a key posttranslational modification of p53 in both normal and malignant neural progenitors and thereby antagonizes the interaction of p53 with promoter elements of multiple target genes. In the absence of Olig2 function, even attenuated levels of p53 are adequate for biological responses to genotoxic damage.
Central nervous system (CNS) involvement is a rare complication of chronic lymphocytic leukemia (CLL) with varied outcomes. We contribute two additional cases of CLL with CNS involvement. The clinical course and response to treatment are described. All 78 previously reported cases of CLL with CNS involvement are presented in this comprehensive review of the literature. CNS involvement of CLL is a rare complication that does not seem to correlate with any evident risk factors. Resolution of CNS symptoms can often be accomplished with intrathecal chemotherapy or irradiation. Early detection and treatment may result in better outcomes in this rare complication.
Although tremendous progress has been made in basic cancer biology and in the development of novel cancer treatments, cancer remains a leading cause of death in the world. The etiopathogenesis of cancer is complex. Besides genetic predisposition, known environmental factors associated with cancer are: diet, lifestyle, and environmental toxins. Toxicity of drugs and eventual relapse of cancers contribute to high cancer death rates. Current therapeutic interventions for cancer- surgery, chemotherapy, radiotherapy, thermotherapy, etc. are far from being curative for many forms of cancer. Chemotherapy, in particular, though the most commonly used cancer treatment, is usually associated with side effects with varying degrees of severity. The purpose of this brief review is to assemble current literature on some crude drugs and to focus on their beneficial roles and drug targets in cancer therapy and chemo-prevention. Although their pharmacological mechanisms and biochemical roles in cancer biology and tumor chemo-prevention are not fully understood, crude drugs are believed to have nutriceutical effects upon cancer patients.
Temozolomide is an oral alkylating agent approved for the treatment of glioblastoma and anaplastic astrocytoma, and is currently under clinical investigation for the treatment of brain metastases from a variety of cancers. Temozolomide is well tolerated, and the reported dermatologic side effects of this medication are limited. Here, the authors report the first case of an urticarial hypersensitivity reaction induced by temozolomide. As this drug will likely be increasingly utilized in the near future, it is important to be aware of its potential to cause adverse cutaneous manifestations.
While the prognosis of patients with glioblastoma (GBM) remains poor despite recent therapeutic advances, variable survival times suggest wide variation in tumor biology and an opportunity for stratified intervention. We used volumetric analysis and morphometrics to measure the spatial relationship between subventricular zone (SVZ) proximity and survival in a cohort of 39 newly diagnosed GBM patients. We collected T2-weighted and gadolinium-enhanced T1-weighted magnetic resonance images (MRI) at pre-operative, post-operative, pre-radiation therapy, and post-radiation therapy time points, measured tumor volumes and distances to the SVZ, and collected clinical data. Univariate and multivariate Cox regression showed that tumors involving the SVZ and tumor growth rate during radiation therapy were independent predictors of shorter progression-free and overall survival. These results suggest that GBMs in close proximity to the ependymal surface of the ventricles convey a worse prognosis-an observation that may be useful for stratifying treatment.
Early detection is important for many solid cancers but the images provided by ultrasound, magnetic resonance imaging (MRI), and computed tomography applied alone or together, are often not sufficient for decisive early screening ? diagnosis. We demonstrate that MRI augmented with fluorescence intensity (FI) substantially improves detection. Early stage murine pancreatic tumors that could not be identified by blinded, skilled observers using MRI alone, were easily identified with MRI along with FI images acquired with photomultiplier tube detection and offset laser scanning. Moreover, we show that fluorescence lifetime (FLT) imaging enables positive identification of the labeling fluorophore and discriminates it from surrounding tissue autofluorescence. Our data suggest combined-modality imaging with MRI, FI, and FLT can be used to screen and diagnose early tumors.
The field of cancer research has experienced significant momentum from the discovery that most malignant tumors harbor subpopulations of cancer cells with stem cell features. Consequently, identification and characterization of so-called cancer-initiating cells or cancer stem cells has also provided novel insights into the biology of malignant brain tumors. Despite an ongoing debate regarding the exact role and identity of cancer stem cells, several studies have suggested that this subpopulation is critical for tumor initiation, tumor progression, angiogenesis and resistance to available therapies. The study of signaling pathways critical to normal neural stem and progenitor cells has also increased our understanding of the mechanisms that drive cancer stem cell-associated tumorigenesis and tumor progression. Novel treatment strategies are being developed to selectively target the molecular pathways relevant to cancer stem cells. This review summarizes important signaling pathways employed by both normal and cancer stem cells and highlights promising molecular-targeted therapies interfering with those signaling pathways in malignant gliomas.
Glioblastoma (GBM) is the most common malignant brain tumor that is characterized by high proliferative rate and invasiveness. Since dysregulation of Notch signaling is implicated in the pathogenesis of many human cancers, here we investigated the role of Notch signaling in GBM. We found that there is aberrant activation of Notch signaling in GBM cell lines and human GBM-derived neurospheres. Inhibition of Notch signaling via the expression of a dominant negative form of the Notch coactivator, mastermind-like 1 (DN-MAML1), or the treatment of a ?-secretase inhibitor, (GSI) MRK-003, resulted in a significant reduction in GBM cell growth in vitro and in vivo. Knockdown of individual Notch receptors revealed that Notch1 and Notch2 receptors differentially contributed to GBM cell growth, with Notch2 having a predominant role. Furthermore, blockade of Notch signaling inhibited the proliferation of human GBM-derived neurospheres in vitro and in vivo. Our overall data indicate that Notch signaling contributes significantly to optimal GBM growth, strongly supporting that the Notch pathway is a promising therapeutic target for GBM.
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