Long-sustaining response in a patient with non-resectable, distant recurrence of glioblastoma multiforme treated by interstitial photodynamic therapy using 5-ALA: case report

Proton MR Spectroscopy and Diffusion MR Imaging Monitoring to Predict Tumor Response to Interstitial Photodynamic Therapy for Glioblastoma

Despite recent progress in conventional therapeutic approaches, the vast majority of glioblastoma recur locally, indicating that a more aggressive local therapy is required. Interstitial photodynamic therapy (iPDT) appears as a very promising and complementary approach to conventional therapies. However, an optimal fractionation scheme for iPDT remains the indispensable requirement. To achieve that major goal, we suggested following iPDT tumor response by a non-invasive imaging monitoring. Nude rats bearing intracranial glioblastoma U87MG xenografts were treated by iPDT, just after intravenous injection of AGuIX® nanoparticles, encapsulating PDT and imaging agents. Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) allowed us an original longitudinal follow-up of post-treatment effects to discriminate early predictive markers. We successfully used conventional MRI, T2 star (T2*), Diffusion Weighted Imaging (DWI) and MRS to extract relevant profiles on tissue cytoarchitectural alterations, local vascular disruption and metabolic information on brain tumor biology, achieving earlier assessment of tumor response. From one day post-iPDT, DWI and MRS allowed us to identify promising markers such as the Apparent Diffusion Coefficient (ADC) values, lipids, choline and myoInositol levels that led us to distinguish iPDT responders from non-responders. All these responses give us warning signs well before the tumor escapes and that the growth would be appreciated.

RIP3 antagonizes a TSC2-mediated pro-survival pathway in glioblastoma cell death

Glioblastomas are the deadliest type of brain cancer and are frequently associated with poor prognosis and a high degree of recurrence despite removal by surgical resection and treatment by chemo- and radio-therapy. Photodynamic therapy (PDT) is a treatment well known to induce mainly necrotic and apoptotic cell death in solid tumors. 5-Aminolevulinic acid (5-ALA)-based PDT was recently shown to sensitize human glioblastoma cells (LN-18) to a RIP3 (Receptor Interacting Protein 3)-dependent cell death which is counter-acted by activation of autophagy. These promising results led us to investigate the pathways involved in cell death and survival mechanisms occurring in glioblastoma following PDT. In the present study, we describe a new TSC2 (Tuberous Sclerosis 2)-dependent survival pathway implicating MK2 (MAPKAPK2) kinase and 14-3-3 proteins which conducts to the activation of a pro-survival autophagy. Moreover, we characterized a new RIP3/TSC2 complex where RIP3 is suggested to promote cell death by targeting TSC2-dependent survival pathway. These results highlight (i) a new role of TSC2 to protect glioblastoma against PDT-induced cell death and (ii) TSC2 and 14-3-3 as new RIP3 partners.

Interstitial photodynamic therapy and glioblastoma: Light fractionation in a preclinical model

BACKGROUND

Glioblastoma is a high-grade cerebral tumor with local recurrence and poor outcome. Photodynamic therapy (PDT) is a localized treatment based on the light activation of a photosensitizer (PS) in the presence of oxygen, which results in the formation of cytotoxic species. The delivery of fractionated light may enhance treatment efficacy by reoxygenating tissues.

OBJECTIVE

To evaluate the efficiency of two light-fractionation schemes using immunohistological data.

MATERIALS AND METHODS

Human U87 cells were grafted into the right putamen of 39 nude rats. After PS precursor intake (5-ALA), an optic fiber was introduced into the tumor. The rats were randomly divided into three groups: without light, with light split into 2 fractions and with light split into 5 fractions. Treatment effects were assessed using brain immunohistology.

RESULTS

Fractionated treatments induced intratumoral necrosis (P < 0.001) and peritumoral edema (P = 0.009) associated with a macrophagic infiltration (P = 0.006). The ratio of apoptotic cells was higher in the 5-fraction group than in either the sham (P = 0.024) or 2-fraction group (P = 0.01). Peripheral vascularization increased after treatment (P = 0.017), and these likely new vessels were more frequently observed in the 5-fraction group (P = 0.028).

CONCLUSION

Interstitial PDT with fractionated light resulted in specific tumoral lesions. The 5-fraction scheme induced more apoptosis but led to greater peripheral neovascularization. Lasers Surg. Med. 49:506-515, 2017. © 2016 Wiley Periodicals, Inc.

Optical technologies for intraoperative neurosurgical guidance

Biomedical optics is a broadly interdisciplinary field at the interface of optical engineering, biophysics, computer science, medicine, biology, and chemistry, helping us understand light-tissue interactions to create applications with diagnostic and therapeutic value in medicine. Implementation of biomedical optics tools and principles has had a notable scientific and clinical resurgence in recent years in the neurosurgical community. This is in great part due to work in fluorescence-guided surgery of brain tumors leading to reports of significant improvement in maximizing the rates of gross-total resection. Multiple additional optical technologies have been implemented clinically, including diffuse reflectance spectroscopy and imaging, optical coherence tomography, Raman spectroscopy and imaging, and advanced quantitative methods, including quantitative fluorescence and lifetime imaging. Here we present a clinically relevant and technologically informed overview and discussion of some of the major clinical implementations of optical technologies as intraoperative guidance tools in neurosurgery.

5-Aminolaevulinic Acid-Induced Fluorescence in Primary Central Nervous System Lymphoma

OBJECTIVE

Diagnosis of primary central nervous system lymphoma (PCNSL) is usually confirmed by brain biopsy and subsequent neuropathologic workup. 5-Aminolevulinic acid (5-ALA)-induced fluorescence has been established for diagnostic and therapeutic purposes in glioma treatment during the last few years and is discussed for use in other cranial tumors. Its role in diagnosis and treatment of PCNSL is still elusive.

METHODS

This retrospective study includes clinical, magnetic resonance imaging, pathologic and surgical data of selected 11 patients with PCNSL at two university hospitals within the last 4 years undergoing surgical treatment for resection because of imminent mass effect or suspected cerebral glioma. Patients received 5-ALA for fluorescence-guided resection preoperatively.

RESULTS

The 11 subjects age ranged from 59 to 81 years. Postsurgical pathologic workup revealed malignant B cell lymphoma with morphologic features of diffuse large B cell lymphoma. Eight of these 11 patients with PCNSL showed a clear fluorescence induced by 5-ALA. After surgical resection, patients were treated with combination chemotherapy regimens.

CONCLUSION

In patients with glioma, the use of 5-ALA is known to be associated with increased extent of resection and survival benefit. Our data and retrospective analysis of a larger patient cohort suggest that the use of 5-ALA in PCNSL should be included in a surgical approach, if this is reconsidered for select patients within a clinical study. In addition, even photodynamic therapy in combination with 5-ALA might be studied.

Imaging and Selective Elimination of Glioblastoma Stem Cells with Theranostic Near-Infrared-Labeled CD133-Specific Antibodies

Near-infrared photoimmunotherapy (NIR-PIT), which employs monoclonal antibody (mAb)-phototoxic phthalocyanine dye IR700 conjugates, permits the specific, image-guided and spatiotemporally controlled elimination of tumor cells. Here, we report the highly efficient NIR-PIT of human tumor xenografts initiated from patient-derived cancer stem cells (CSCs). Using glioblastoma stem cells (GBM-SCs) expressing the prototypic CSC marker AC133/CD133, we also demonstrate here for the first time that NIR-PIT is highly effective against brain tumors. The intravenously injected theranostic AC133 mAb conjugate enabled the non-invasive detection of orthotopic gliomas by NIR fluorescence imaging, and reached AC133+ GBM-SCs at the invasive tumor front. AC133-targeted NIR-PIT induced the rapid cell death of AC133+ GBM-SCs and thereby strong shrinkage of both subcutaneous and invasively growing brain tumors. A single round of NIR-PIT extended the overall survival of mice with established orthotopic gliomas by more than a factor of two, even though the harmless NIR light was applied through the intact skull. Humanised versions of this theranostic agent may facilitate intraoperative imaging and histopathological evaluation of tumor borders and enable the highly specific and efficient eradication of CSCs.

Dexamethasone alone and in combination with desipramine, phenytoin, valproic acid or levetiracetam interferes with 5-ALA-mediated PpIX production and cellular retention in glioblastoma cells

Extent of resection of glioblastoma (GBM) correlates with overall survival. Fluorescence-guided resection (FGR) using 5-aminolevulinic acid (5-ALA) can improve the extent of resection. Unfortunately not all patients given 5-ALA accumulate sufficient quantities of protoporphyrin IX (PpIX) for successful FGR. In this study, we investigated the effects of dexamethasone, desipramine, phenytoin, valproic acid, and levetiracetam on the production and accumulation of PpIX in U87MG cells. All of these drugs, except levetiracetam, reduce the total amount of PpIX produced by GBM cells (p < 0.05). When dexamethasone is mixed with another drug (desipramine, phenytoin, valproic acid or levetiracetam) the amount of PpIX produced is further decreased (p < 0.01). However, when cells are analyzed for PpIX cellular retention, dexamethasone accumulated significantly more PpIX than the vehicle control (p < 0.05). Cellular retention of PpIX was not different from controls in cells treated with dexamethasone plus desipramine, valproic acid or levetiracetam, but was significantly less for dexamethasone plus phenytoin (p < 0.01). These data suggest that medications given before and during surgery may interfere with PpIX accumulation in malignant cells. At this time, levetiracetam appears to be the best medication in its class (anticonvulsants) for patients undergoing 5-ALA-mediated FGR.

Polyacrylamide gel substrates that simulate the mechanical stiffness of normal and malignant neuronal tissues increase protoporphyin IX synthesis in glioma cells

Protoporphyrin IX (PPIX) produced following the administration of exogenous 5d-aminolevulinic acid is clinically approved for photodynamic therapy and fluorescence-guided resection in various jurisdictions around the world. For both applications, quantification of PPIX forms the basis for accurate therapeutic dose calculation and identification of malignant tissues for resection. While it is well established that the PPIX synthesis and accumulation rates are subject to the cell’s biochemical microenvironment, the effect of the physical microenvironment, such as matrix stiffness, has received little attention to date. Here we studied the proliferation rate and PPIX synthesis and accumulation in two glioma cell lines U373 and U118 cultured under five different substrate conditions, including the conventional tissue culture plastic and polyacrylamide gels that simulated tissue stiffness of normal brain (1 kPa) and glioblastoma tumors (12 kPa). We found that the proliferation rate increased with substrate stiffness for both cell lines, but not in a linear fashion. PPIX concentration was significantly higher in cells cultured on tissue-simulating gels than on the much stiffer tissue culture plastic for both cell lines. These findings, albeit preliminary, suggest that the physical microenvironment might be an important determinant of tumor aggressiveness and PPIX synthesis in glioma cells.

Fluorescence in neurosurgery: Its diagnostic and therapeutic use. Review of the literature

Fluorescent agents, e.g. 5-aminolevulinic acid (5-ALA), fluorescein and indocyanine green (ICG) are in common use in neurosurgery for tumor resection and neurovascular surgery. Protoporphyrine IX (PPIX) as major metabolite of 5-ALA is a strong fluorescent substance accumulated within malignant glioma tissue and a very sensitive and specific tool for visualizing high grade glioma tissue during surgery. Furthermore, 5-ALA or rather PPIX also offers an intratumoral therapeutic option stimulated by laser light in specific wavelength. Fluorescein was demonstrated to show similar fluorescent reactions in neurosurgery, but is controversial in its use, especially in high grade tumor surgery. Intraoperative angiography during resection of arterio-venous malformations, extracranial-intracranial-bypass or aneurysm surgery is supported by ICG fluorescence. Generally ICG will provide beneficial information for both, exposure of the pathology and illustration of healthy structures. This manuscript shows an overview of the literature focussing fluorescence in neurosurgery.

Peptide-Targeted Gold Nanoparticles for Photodynamic Therapy of Brain Cancer

Targeted drug delivery using epidermal growth factor peptide-targeted gold nanoparticles (EGFpep-Au NPs) is investigated as a novel approach for delivery of photodynamic therapy (PDT) agents, specifically Pc 4, to cancer. In vitro studies of PDT show that EGFpep-Au NP-Pc 4 is twofold better at killing tumor cells than free Pc 4 after increasing localization in early endosomes. In vivo studies show that targeting with EGFpep-Au NP-Pc 4 improves accumulation of fluorescence of Pc 4 in subcutaneous tumors by greater than threefold compared with untargeted Au NPs. Targeted drug delivery and treatment success can be imaged via the intrinsic fluorescence of the PDT drug Pc 4. Using Pc 4 fluorescence, it is demonstrated in vivo that EGFpep-Au NP-Pc 4 impacts biodistribution of the NPs by decreasing the initial uptake by the reticuloendothelial system (RES) and by increasing the amount of Au NPs circulating in the blood 4 h after IV injection. Interestingly, in vivo PDT with EGFpep-Au NP-Pc 4 results in interrupted tumor growth when compared with EGFpep-Au NP control mice when selectively activated with light. These data demonstrate that EGFpep-Au NP-Pc 4 utilizes cancer-specific biomarkers to improve drug delivery and therapeutic efficacy over untargeted drug delivery.

Nanosurgical resection of malignant brain tumors: beyond the cutting edge

Advances in surgical procedures and improvements in patient outcomes have resulted from applications of new technologies in the operating room over the past three decades. All surgeons would be excited about the possibilities of improving their resections of tumors for patients with cancer if a new technology were introduced to facilitate this. In this issue of ACS Nano, Karabeber et al. use a hand-held Raman scanner to probe the completeness of resection of glioblastoma multiforme (GBM), the most malignant brain cancer, in a genetically engineered mouse model. They show that the hand-held scanner could accurately detect gold-silica surface-enhanced Raman scattering nanoparticles embedded within the GBM, resulting in a complete tumor resection. In this Perspective, we review potential applications of nanotechnologies to neurosurgery and describe how new systems, such as the one described in this issue, may be brought closer to the operating room through modifications in nanoparticle size, overcoming the obstacles presented by the blood-brain barrier, and functionalizing nanoparticle conjugates so that they reach their target at highest concentrations possible. Finally, with adaptations of the actual hand-held Raman scanner device itself, one can envision the day when "nanosurgical" procedures will be a part of the surgeon's armamentarium.

Successful in vivo tumor visualization using fluorescence laparoscopy in a mouse model of disseminated alveolar rhabdomyosarcoma

BACKGROUND

Surgery for rhabdomyosarcoma is challenging due to a lack of clear delineation between tumor and surrounding tissue. Mutilating surgery can be necessary in difficult tumor localizations. Therefore, novel diagnostic and therapeutic modalities are required. The aim of this study was to evaluate the in vivo tumor detection of RMS using fluorescence laparoscopy and to analyze the efficacy of hypericin-induced photodynamic therapy in a mouse model.

METHODS

Seventeen NOD/LtSz-scid IL2Rγnull-mice were divided into four groups. In group 1, mCherry-expressing tumor cells and in group 2-4 non-transfected tumor cells were xenotransplanted. Three weeks later, one fluorochrome per group (ICG, ICG-cetuximab, hypericin) was injected. Fluorescence laparoscopy was carried out and tumors were resected using fluorescence guidance. In the hypericin group, photodynamic therapy was performed using blue light and apoptosis was evaluated by TUNEL test.

RESULTS

A clear discrimination between healthy and tumor tissue was feasible by fluorescending properties with mCherry expressing tumor cells and after injection of hypericin. No fluorescence was detected in mice injected with ICG and ICG-labeled cetuximab. Hypericin photodynamic therapy induced apoptosis of tumor cells after exposure to blue light.

CONCLUSIONS

Intraoperative photodynamic diagnosis was feasible using mCherry-transfected tumor cells or hypericin. Additionally, intraoperative photodynamic therapy was possible and effective.

Kinetics of porphyrin fluorescence accumulation in pediatric brain tumor cells incubated in 5-aminolevulinic acid

BACKGROUND

Fluorescence-guided surgery with 5-aminolevulinic acid (5-ALA) enables more complete resections of tumors in adults. 5-ALA elicits accumulation of fluorescent porphyrins in various cancerous tissues, which can be visualized using a modified neurosurgical microscope with blue light. Although this technique is well established in adults, it has not been investigated systematically in pediatric brain tumors. Specifically, it is unknown how quickly, how long, and to what extent various pediatric tumors accumulate fluorescence. The purpose of this study was to determine utility and time course of 5-ALA-induced fluorescence in typical pediatric brain tumors in vitro.

METHODS

Cell cultures of medulloblastoma [DAOY and UW228], cPNET [PFSK] atypical teratoid rhabdoid tumor [BT16] and ependymoma [RES196] were incubated with 5-ALA for either 60 minutes or continuously. Porphyrin fluorescence intensities were determined using a fluorescence-activated cell sorter (FACS) after 1, 3, 6, 9, 12 and 24 hours. C6 and U87 cells served as controls.

RESULTS

All pediatric brain tumor cell lines displayed fluorescence compared to their respective controls without 5-ALA (p < 0.05). Sixty minutes of incubation resulted in peaks between 3 and 6 hours, whereas continuous incubation resulted in peaks at 12 hours or beyond. 60 minute incubation peak levels were between 52 and 91 % of maxima achieved with continuous incubation. Accumulation and clearance varied between cell types.

CONCLUSIONS

We demonstrate that 5-ALA exposure of cell lines derived from typical pediatric central nervous system (CNS) tumors induces accumulation of fluorescent porphyrins. Differences in uptake and clearance indicate that different application modes may be necessary for fluorescence-guided resection, depending on tumor type.

Protoporphyrin IX fluorescence and photobleaching during interstitial photodynamic therapy of malignant gliomas for early treatment prognosis

BACKGROUND AND OBJECTIVE

Interstitial photodynamic therapy (iPDT) of non-resectable recurrent glioblastoma using 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) has shown a promising outcome. It remained unclear, however, to what extent inter- and intra-tumoural differences of PpIX concentrations influence the efficacy of iPDT. In the current pilot study, we analysed PpIX concentrations quantitatively and assessed PpIX induced fluorescence and photobleaching intraoperatively.

MATERIALS AND METHODS

Five patients harbouring non-resectable glioblastomas were included. ALA (20 or 30 mg/kg body weight) was given 5-8 hours before treatment. Stereotactic biopsies were taken throughout the tumour volume for both histological analysis and determination of PpIX concentrations, which were measured by chemical extraction. Cylindrical light diffusors were stereotactically implanted. Prior to and after irradiation, fluorescence measurements were performed. Outcome measurement was based on clinical and neuro-radiological follow up.

RESULTS

In three patients, a strong PpIX fluorescence was seen before treatment, which was completely photobleached after iPDT. High concentrations of PpIX could be detected in viable tumour parts of these patients (mean PpIX uptake per tumour: 1.4-3.0 µM). In the other two patients, however, no or only low PpIX uptake (0-0.6 µM) could be detected. The patients with strong PpIX uptake showed treatment response and long-term clinical stabilisation (no progression in 29, 30 and 36 months), early treatment failure was seen in the remaining two patients (death after 3 and 9 months).

CONCLUSIONS

Intra-tumoural PpIX concentrations exhibited pronounced inter- and intra-tumoural variations in glioblastoma, which are directly linked to variable degrees of fluorescence intensity. High intra-tumoural PpIX concentrations with strong fluorescence intensity and complete photobleaching after iPDT seem to be associated with favourable outcome. Real-time monitoring of PpIX fluorescence intensity and photobleaching turned out to be feasible and safe and might be employed for early treatment prognosis of iPDT.

Aminolevulinic acid (ALA): photodynamic detection and potential therapeutic applications

Aminolevulinic acid (ALA) is a heme precursor that may have potential applications for photodynamic detection and photodynamic therapy-based treatment of solid tumors in a variety of malignancies. ALA may have a role in other applications in surgical oncology based on its ability to discriminate neoplastic tissue from adjacent normal tissue. In this review, we provide a comprehensive summary of the published studies of ALA in noncutaneous solid malignancies.

Migration of mesenchymal stem cells towards glioblastoma cells depends on hepatocyte-growth factor and is enhanced by aminolaevulinic acid-mediated photodynamic treatment

Hepatocyte-growth factor (HGF) is expressed by glioblastomas and contributes to their growth, migration and invasion. HGF also mediates migration of mesenchymal stem cells (MSC) to sites of apoptotic cell death. Moreover, MSC show tropism for glioblastomas, which is exploited in gene therapy to deliver the therapeutics to the tumor cells. Here, we have studied whether HGF contributes to the recruitment of MSC by glioblastoma cells and whether aminolaevulinic acid-mediated photodynamic therapy (ALA/PDT), a novel therapeutic approach that induces apoptosis in glioblastoma cells, affects HGF release and this migratory response. MSC expressed the HGF receptor MET and migrated towards U87 and U251 glioblastoma spheroids. Migration increased significantly when spheroids were subjected to ALA/PDT, which was associated with induction of apoptosis and up-regulation of HGF. Neutralizing HGF resulted in significant inhibition of MSC migration towards untreated as well as ALA/PDT-treated spheroids. Thus, glioblastoma cells express HGF, which contributes to the attraction of MSC. ALA/PDT induces apoptosis and augments HGF release causing enhanced MSC migration towards the tumor cells. ALA/PDT may therefore be exploited to improve targeting of MSC delivered gene therapy, but it may also constitute a risk in terms of beneficial effects for the tumor.

Response assessment of bevacizumab in patients with recurrent malignant glioma using [18F]Fluoroethyl-L-tyrosine PET in comparison to MRI

PURPOSE

To investigate prospectively the potential of O-(2-[(18)F]fluoroethyl)-L-tyrosine ((18)F-FET) PET in comparison to MRI for the assessment of the response of patients with recurrent high-grade glioma (rHGG) to antiangiogenic treatment.

METHODS

Ten patients with rHGG were treated biweekly with bevacizumab/irinotecan (BEV/IR). MR images and dynamic (18)F-FET PET scans were obtained at baseline and at follow-up after the start of treatment (median 4.9 weeks). Using MRI treatment response was evaluated according to RANO (Response Assessment in Neuro-Oncology) criteria. For (18)F-FET PET evaluation, a reduction >45 % of the metabolically active tumour volume was considered as a treatment response, with the metabolically active tumour being defined as a tumour-to-brain ratio (TBR) of ≥1.6. The results of the treatment assessments were related to progression-free survival (PFS) and overall survival (OS). For further evaluation of PET data, maximum and mean TBR were calculated using region-of-interest analysis at baseline and at follow-up. Additionally, (18)F-FET uptake kinetic studies were performed at baseline and at follow-up in all patients. Time-activity curves were generated and the times to peak (TTP) uptake (in minutes from the beginning of the dynamic acquisition to the maximum uptake) were calculated.

RESULTS

At follow-up, MRI showed a complete response according to RANO criteria in one of the ten patients (10 %), a partial response in five patients (50 %), and stable disease in four patients (40 %). Thus, MRI did not detect tumour progression. In contrast, (18)F-FET PET revealed six metabolic responders (60 %) and four nonresponders (40 %). In the univariate survival analyses, a response detected by (18)F-FET PET predicted a significantly longer PFS (median PFS, 9 vs. 3 months; P = 0.001) and OS (median OS 23.0 months vs. 3.5 months; P = 0.001). Furthermore, in four patients (40 %), diagnosis according to RANO criteria and by (18)F-FET PET was discordant. In these patients, PET was able to detect tumour progression earlier than MRI (median time benefit 10.5 weeks; range 6-12 weeks). At baseline and at follow-up, in nonresponders TTP was significantly shorter than in responders (baseline TTP 10 ± 8 min vs. 35 ± 9 min; P = 0.002; follow-up TTP 23 ± 9 min vs. 39 ± 8 min; P = 0.02). Additionally, at baseline a kinetic pattern characterized by an early peak of (18)F-FET uptake followed by a constant descent was more frequently observed in the nonresponders (P = 0.018).

CONCLUSION

Both standard and kinetic imaging parameters derived from(18)F-FET PET seem to predict BEV/IR treatment failure and thus contribute important additional information for clinical management over and above the information obtained by MRI response assessment based on RANO criteria.

Gefitinib enhances the efficacy of photodynamic therapy using 5-aminolevulinic acid in malignant brain tumor cells

BACKGROUND

Since the ATP-binding cassette transporter ABCG2 plays a physiologically significant role of porphyrin efflux from living cells, the expression of ABCG2 may influences the efficacy of photodynamic therapy (PDT). In this study, we evaluated the effect of gefitinib, a potent ABCG2 inhibitor, on 5-aminolevulinic acid (5-ALA)-PDT in brain tumor cell lines in vitro.

MATERIALS AND METHODS

Four human glioma cell lines (U87MG, U118MG, A172, and T98G) and a malignant meningioma cell line (IOMM-Lee) were incubated with gefitinib (0.01-1.0μM) before incubation with 5-ALA (1mM). The effects gefitinib on intracellular protoporphyrin IX (PpIX), mRNA and protein expression of ABCG2, and PDT were evaluated, in vitro.

RESULTS

At concentrations of 0.1μM or higher, gefitinib enhanced intracellular levels of PpIX in a dose-dependent manner in all those cell lines. Gefitinib decreased mRNA and plasma membrane protein expression of ABCG2, and efficiently enhanced the effect of 5-ALA-PDT in malignant brain tumor cells.

CONCLUSION

Gefitinib can inhibit ABCG2-mediated PpIX efflux from malignant brain tumor cells to increase the intracellular PpIX and thereby enhance the PDT effect.

Contribution of case reports to glioblastoma research: systematic review and analysis of pattern of citation

INTRODUCTION

Research activity related to different aspects of diagnosis, epidemiology and treatment of glioblastoma has increased during recent years. Authors of scientific publications are able to choose between different formats including case reports. Little is known about their influence on advancement of the field or scientific merits. Do glioblastoma case reports attract attention or do they go largely unrecognized?

METHODS

Different measures of impact, visibility and quality of published research are available, each with its own pros and cons. For the present evaluation (to the best of our knowledge the first one on this subject), article citation rate was chosen. The databases PubMed and Scopus were searched for articles that were published during the 5-year time period between 2006 and 2010.

RESULTS

We identified 5831 articles dealing with glioblastoma. Of these, 286 (4.9%) reported on single patient cases and 15 (0.26%) were reports of two cases. The median number of citations was 1 (range 0-37). Stratified by year of publication, the median number ranged from 0 for those published in 2010 to 3 for those published in 2006. Citations appeared to gradually increase during the first 2-3 years after publication. As compared to other articles, case reports were significantly less likely to receive a large number of citations.

CONCLUSION

Compared to other formats, the proportion of case reports was limited and few of them were highly cited. It cannot be excluded that case reports without citation provide interesting information to some readers. However, their educational value is difficult to quantify.

Preliminary clinical report on safety and efficacy of photodynamic therapy using talaporfin sodium for malignant gliomas

OBJECTIVES

To investigate the safety and efficacy of photodynamic therapy (PDT) using talaporfin sodium in patients with surgically, completely unresectable malignant gliomas with invasion into the eloquent areas of the brain associated with language and motor functions.

MATERIALS AND METHODS

Subjects consisted of consecutive 14 adult patients with malignant gliomas that were shown on preoperative diagnostic imaging to have invaded the eloquent areas of the brain. Of these, 6 patients had newly diagnosed tumors and 8 patients had recurrent tumors. In 15 craniotomy and tumor resection procedures, PDT was used as additional intraoperative treatment 24 h after 40 mg/m(2) of talaporfin sodium had been injected intravenously. After the tumor bulk had been resected as extensively as possible either 1 or 2 sites of probable tumor invasion in the bottom of resection cavity were irradiated superficially with a 664-nm diode laser for 180 s (27 J/cm(2)) at a power density of 150 mW/cm(2).

RESULTS

PDT achieved a response rate of 80% at the treated sites in the 6 patients with newly diagnosed malignant gliomas. In these patients, the median progression-free survival time was 23 months. The median survival time in 3 patients who died was 26 months, and the remaining 3 patients survived for more than 3 years with a good Karnofsky Performance Scale (KPS). In the 8 patients with recurrent tumors who received PDT, their response rate was low (25.0%), their gliomas recurred 3 months after PDT, and their survival time was only 9 months following PDT. No adverse events directly attributable to PDT occurred in any patients. Protection against light was only required for approximately 3 days after PDT.

CONCLUSION

We examined the safety and efficacy of PDT using talaporfin sodium as an additional intraoperative treatment for malignant glioma. PDT in addition to surgical resection achieved better therapeutic results than conventional protocols, especially in patients with newly diagnosed malignant gliomas. However, the current methodology has some limitations with respect to patients with recurrent tumors. Larger-scale studies are required to confirm the clinical feasibility of PDT plus surgery.

5-ALA-PDT induces RIP3-dependent necrosis in glioblastoma

Glioblastoma constitute the most frequent and deadliest brain tumors of astrocytic origin. They are resistant to all current therapies and are associated with a high rate of recurrence. Glioblastoma were previously shown to respond to treatments by 5-aminolevulinic acid (5-ALA)-based photodynamic therapy (PDT) mainly by activating a necrotic type of cell death. The receptor-interacting protein 3 (RIP3) has recently been outlined as a key mediator of this caspase-independent form of programmed cell death. In the present study, we analyzed the necrotic mechanism induced by 5-ALA-PDT in human glioblastoma cells and explored the role of RIP3 in this context. Our results show that PDT-induced necrosis is dependent on RIP3, which forms aggregates and colocalizes with RIP1 following photosensitization. We demonstrate that PDT-mediated singlet oxygen production is the cause of RIP3-dependent necrotic pathway activation. We also prove that PDT induces the formation of a pro-necrotic complex containing RIP3 and RIP1 but lacking caspase-8 and FADD, two proteins usually part of the necrosome when TNF-α is used as a stimulus. Thus, we hypothesize that PDT might lead to the formation of a different necrosome whose components, besides RIP1 and RIP3, are still unknown. In most cases, glioblastoma are characterized by a constitutive activation of NF-κB. This factor is a key regulator of various processes, such as inflammation, immune response, cell growth or apoptosis. Its inhibition was shown to further sensitize glioblastoma cells to PDT-induced necrosis, however, no difference in RIP3 upshift or aggregation could be observed when NF-κB was inhibited.

Heat-shock protein 70-dependent dendritic cell activation by 5-aminolevulinic acid-mediated photodynamic treatment of human glioblastoma spheroids in vitro

BACKGROUND

T-cell responses contribute to the anti-tumoural effect of photodynamic therapy (PDT). For such responses to occur, dendritic cells (DCs) have to migrate to the tumour, take up tumour antigens and respond to danger signals with maturation, before they engage in T-cell activation. Here, we have studied the effect of 5-aminolevulinic acid (ALA)-mediated PDT on DCs in vitro in a human spheroid model of glioblastoma (GB).

METHODS

Spheroids of the GB cell lines U87 and U251 were treated with ALA/PDT, and effects on attraction, uptake of tumour antigens and maturation of DCs were studied. To block heat-shock protein-70 (HSP-70) on the spheroids, neutralising antibodies were used.

RESULTS

5-Aminolevulinic acid /PDT-treated GB spheroids attracted DCs that acquired tumour antigens from the spheroids effectively. Moreover, co-culture with ALA/PDT-treated spheroids induced DC maturation as indicated by the upregulation of CD83 and co-stimulatory molecules as well as increased T-cell stimulatory activity of the DCs. Heat-shock protein-70 was upregulated on the spheroids after ALA/PDT treatment. Uptake of tumour antigens and DC maturation induced by the ALA/PDT-treated spheroids were inhibited when HSP-70 was blocked.

CONCLUSION

ALA/PDT treatment of glioma spheroids promotes the three initial steps of the afferent phase of adaptive immunity, which is at least partially mediated by HSP-70.

Modulation of migratory activity and invasiveness of human glioma spheroids following 5-aminolevulinic acid–based photodynamic treatment

Object

Five-aminolevulinic acid–mediated photodynamic therapy (ALA/PDT) can improve the clinical outcome in patients suffering from glioblastoma. Besides direct phototoxicity, additional mechanisms may contribute. Therefore, the authors studied the influence of ALA/PDT on glioblastoma's migratory and invasive behavior in a human glioma cell spheroid model.

Methods

Glioma spheroids were grown from human U373 and A172 cell lines. After ALA/PDT of spheroids, the authors assessed the migration of tumor cells and their capacity to invade a collagen matrix, as well as changes in their viability, morphology, and expression of matrix metalloproteinases (MMPs).

Results

The authors found that ALA/PDT caused long-lasting, nearly complete suppression of glioma cell migration and matrix invasion compared with nontherapeutic controls, including either irradiation or incubation with ALA only. Although ALA/PDT induced tumor cell apoptosis, suppression of migration/invasion was not simply due to phototoxicity because 50% of tumor cells remained vital throughout the observation period. Moreover, the morphology of ALA/PDT-treated cells changed significantly toward a polygonal, epithelial-like appearance, which was associated with alterations in the actin cytoskeleton. Furthermore, downregulation of MMP-7 and -8 was observed after treatment whereas other MMPs remained unchanged.

Conclusions

In addition to directly eliminating glioma cells through apoptosis, ALA/PDT alters their invasiveness, possibly due to the effects on the cytoskeletal organization and MMP expression.

Induction of immune mediators in glioma and prostate cancer cells by non-lethal photodynamic therapy

Background

Photodynamic therapy (PDT) uses the combination of photosensitizing drugs and harmless light to cause selective damage to tumor cells. PDT is therefore an option for focal therapy of localized disease or for otherwise unresectable tumors. In addition, there is increasing evidence that PDT can induce systemic anti-tumor immunity, supporting control of tumor cells, which were not eliminated by the primary treatment. However, the effect of non-lethal PDT on the behavior and malignant potential of tumor cells surviving PDT is molecularly not well defined.

Methodology/Principal Findings

Here we have evaluated changes in the transcriptome of human glioblastoma (U87, U373) and human (PC-3, DU145) and murine prostate cancer cells (TRAMP-C1, TRAMP-C2) after non-lethal PDT in vitro and in vivo using oligonucleotide microarray analyses. We found that the overall response was similar between the different cell lines and photosensitizers both in vitro and in vivo. The most prominently upregulated genes encoded proteins that belong to pathways activated by cellular stress or are involved in cell cycle arrest. This response was similar to the rescue response of tumor cells following high-dose PDT. In contrast, tumor cells dealing with non-lethal PDT were found to significantly upregulate a number of immune genes, which included the chemokine genes CXCL2, CXCL3 and IL8/CXCL8 as well as the genes for IL6 and its receptor IL6R, which can stimulate proinflammatory reactions, while IL6 and IL6R can also enhance tumor growth.

Conclusions

Our results indicate that PDT can support anti-tumor immune responses and is, therefore, a rational therapy even if tumor cells cannot be completely eliminated by primary phototoxic mechanisms alone. However, non-lethal PDT can also stimulate tumor growth-promoting autocrine loops, as seen by the upregulation of IL6 and its receptor. Thus the efficacy of PDT to treat tumors may be improved by controlling unwanted and potentially deleterious growth-stimulatory pathways.

Current and future clinical applications for optical imaging of cancer: from intraoperative surgical guidance to cancer screening

Optical imaging is an inexpensive, fast, and sensitive imaging approach for the noninvasive detection of human cancers in locations that are accessible by an optical imaging device. Light is used to probe cellular and molecular function in the context of cancer in the living body. Recent advances in the development of optical instrumentation make it possible to detect optical signals produced at a tissue depth of several centimeters. The optical signals can be endogenous contrasts that capture the heterogeneity and biological status of different tissues, including tumors, or extrinsic optical contrasts that selectively accumulate in tumors to be imaged after local or systemic delivery. The use of optical imaging is now being applied in the clinic and operating room for the localization and resection of malignant tumors in addition to screening for cancer.

5-Aminolevulinic acid-induced protoporphyrin IX levels in tissue of human malignant brain tumors

Protoporphyrin IX (PpIX) produced from exogenous, orally administered 5-aminolevulinic acid (ALA) displays high tumor-selective uptake and is being successfully employed for fluorescence-guided resection (FGR) of human malignant gliomas. Furthermore, the phototoxicity of PpIX can be utilized for photodynamic therapy (PDT) of brain tumors, which has been shown previously. Here, the absolute PpIX concentration in human brain tissue was investigated following oral ALA administration (20 mg kg(-1) b.w.). An extraction procedure was used to quantify PpIX in macroscopic tissue samples, weighing 0.013-0.214 g, obtained during FGR. The PpIX concentration was significantly higher in vital grade IV tumors (5.8 ± 4.8 μm, mean ± SD, range 0-28.2 μm, n = 8) as compared with grade III tumors (0.2 ± 0.4 μm, mean ± SD, range 0-0.9 μm, n = 4). There was also a large heterogeneity within grade IV tumors with PpIX displaying significantly lower levels in infiltration zones and necrotic regions as compared with vital tumor parts. The average PpIX concentration in vital grade IV tumor parts was in the range previously shown sufficient for PDT-induced tissue damage following irradiation. However, the feasibility of PDT for grade III brain tumors and for grade IV brain tumors displaying mainly necrotic tissue areas without solid tumor parts needs to be further investigated.

[Local therapy of primary brain tumors]

In recent years further forms of local treatment for primary brain tumors have been developed in addition to resection and radiation. There are basically three principles for local therapy, intralesional therapy for primary or recurrent non-resectable tumors as well as intracavitary and pericavitary therapy following microscopic surgical complete resection. Local therapy procedures are complex and suffer from special difficulties in the evaluation of their effectiveness by imaging techniques, because they are inevitably accompanied by alterations in the imaging, barrier disturbances and contrast medium uptake.

Real-time intraoperative fluorescence imaging system using light-absorption correction

We present a novel fluorescence imaging system developed for real-time interventional imaging applications. The system implements a correction scheme that improves the accuracy of epi-illumination fluorescence images for light intensity variation in tissues. The implementation is based on the use of three cameras operating in parallel, utilizing a common lens, which allows for the concurrent collection of color, fluorescence, and light attenuation images at the excitation wavelength from the same field of view. The correction is based on a ratio approach of fluorescence over light attenuation images. Color images and video is used for surgical guidance and for registration with the corrected fluorescence images. We showcase the performance metrics of this system on phantoms and animals, and discuss the advantages over conventional epi-illumination systems developed for real-time applications and the limits of validity of corrected epi-illumination fluorescence imaging.