Optimization of high-grade glioma resection using 5-ALA fluorescence-guided surgery: A literature review and practical recommendations from the neuro-oncology club of the French society of neurosurgery

Enhancing the Extent of Resection in Glioma Surgery Through the Integration of Intraoperative Contrast-Enhanced Ultrasound and Fluorescein Sodium

OBJECTIVE

Due to the infiltrative nature and high local recurrence of gliomas, particularly high-grade gliomas, gross total resection (GTR) of a tumor is the first critical step in treatment. This study aimed to determine whether the integration of intraoperative contrast-enhanced ultrasound (CEUS) and fluorescein sodium can improve the identification of tumor boundaries and residuals, and increasethe extent of resection (EOR) to better protect neurological function.

METHODS

We retrospectively analysed clinical data from 87 glioma surgeries and categorised the patients into 3 groups: CEUS plus fluorescein sodium, fluorescein sodium alone and microsurgery alone.

RESULTS

In terms of EOR, GTR was achieved in 22 (91.7%) patients in the CEUS plus fluorescein sodium group, which was significantly higher than that in other groups. In the subgroup analysis of tumors with lobulated or satellite lesions and WHO grade III or IV gliomas, CEUS plus fluorescein sodium group showed the highest GTR (86.7% and 88.9% respectively) among the groups. Logistic regression analysis of factors that may affect the GTR of tumors showed that the functional areas involvement and the presence of lobulated or satellite lesions were risk factors, whereas CEUS plus fluorescein sodium group was a protective factor. However, CEUS plus fluorescein sodium group had the longest surgery time.

CONCLUSIONS

Intraoperative CEUS with fluorescein sodium is a real-time, straightforward, safe, and effective approach to perform surgical resection of gliomas. This approach assists surgeons in identifying tumor boundaries, residual tumors, and normal brain parenchyma, which increases the EOR.

Comparison of minimal detectable protoporphyrin IX concentrations with a loupe device and conventional 5-ALA fluorescence microscopy: an experimental study

Significance

The 5-aminolevulinic acid (5-ALA) fluorescence technique is now widely applied for intraoperative visualization of specific central nervous system (CNS) tumors. Previous technical implementations of this technique have relied on specifically modified surgical microscopes to visualize intratumoral fluorescent protoporphyrin (PpIX). While this approach evidently allows for reliable intraoperative tumor visualization, it requires the availability of specifically modified surgical microscopes and their use even in cases where the operating neurosurgeon would prefer to use surgical loupes. Recently, a novel loupe device was introduced that is also capable of visualizing 5-ALA fluorescence.

Aim

The aim of this study was therefore to compare the detected PpIX concentrations between the conventional fluorescence microscope and the novel loupe device.

Approach

We used fluorescence phantoms of different PpIX concentrations for comparison between a conventional fluorescence microscope and the novel loupe device. For this purpose, we created fluorescence images using the excitation light sources of the conventional fluorescence microscope and the loupe device with both available background illumination modes (low and high). Subsequently, the minimal detectable PpIX concentrations according to each technique were determined by five independent neurosurgeons.

Results

Using the conventional fluorescence microscope, the median minimal detectable PpIX concentration was 0.16    μ g / ml (range: 0.15 to 0.17    μ g / ml ). By the loupe device, the median minimal detectable PpIX concentration was 0.12    μ g / ml (range: 0.10 to 0.12    μ g / ml ) and 0.08    μ g / ml (range: 0.07 to 0.08    μ g / ml ) for the high- and low-modes, respectively. Altogether, the minimal detectable PpIX concentrations were significantly lower using the loupe device compared to the conventional fluorescence microscope (p = 0.007 ).

Conclusions

Our data indicate that the novel loupe device is able to visualize 5-ALA fluorescence with high sensitivity and thus might serve as a powerful tool for visualization of specific CNS tumors in the future.

Combinatorial approaches to effective therapy in glioblastoma (GBM): Current status and what the future holds

The aggressive and recurrent nature of glioblastoma is multifactorial and has been attributed to its biological heterogeneity, dysfunctional metabolic signaling pathways, rigid blood-brain barrier, inherent resistance to standard therapy due to the stemness property of the gliomas cells, immunosuppressive tumor microenvironment, hypoxia and neoangiogenesis which are very well orchestrated and create the tumor's own highly pro-tumorigenic milieu. Once the relay of events starts amongst these components, eventually it becomes difficult to control the cascade using only the balanced contemporary care of treatment consisting of maximal resection, radiotherapy and chemotherapy with temozolamide. Over the past few decades, implementation of contemporary treatment modalities has shown benefit to some extent, but no significant overall survival benefit is achieved. Therefore, there is an unmet need for advanced multifaceted combinatorial strategies. Recent advances in molecular biology, development of innovative therapeutics and novel delivery platforms over the years has resulted in a paradigm shift in gliomas therapeutics. Decades of research has led to emergence of several treatment molecules, including immunotherapies such as immune checkpoint blockade, oncolytic virotherapy, adoptive cell therapy, nanoparticles, CED and BNCT, each with the unique proficiency to overcome the mentioned challenges, present research. Recent years are seeing innovative combinatorial strategies to overcome the multifactorial resistance put forth by the GBM cell and its TME. This review discusses the contemporary and the investigational combinatorial strategies being employed to treat GBM and summarizes the evidence accumulated till date.

The use of radiosensitizing agents in the therapy of glioblastoma multiforme-a comprehensive review

BACKGROUND

Glioblastoma is the most common malignant brain tumor in human adults. Despite several improvements in resective as well as adjuvant therapy over the last decades, its overall prognosis remains poor. As a means of improving patient outcome, the possibility of enhancing radiation response by using radiosensitizing agents has been tested in an array of studies.

METHODS

A comprehensive review of clinical trials involving radiation therapy in combination with radiosensitizing agents on patients diagnosed with glioblastoma was performed in the National Center for Biotechnology Information's PubMed database.

RESULTS

A total of 96 papers addressing this matter were published between 1976 and 2021, of which 63 matched the subject of this paper. All papers were reviewed, and their findings discussed in the context of their underlining mechanisms of radiosensitization.

CONCLUSION

In the history of glioblastoma treatment, several approaches of optimizing radiation-effectiveness using radiosensitizers have been made. Even though several different strategies and agents have been explored, clear evidence of improved patient outcome is still missing. Tissue-selectiveness and penetration of the blood-brain barrier seem to be major roadblocks; nevertheless, modern strategies try to circumvent these obstacles, using novel sensitizers based on preclinical data or alternative ways of delivery.

What matters for people with brain cancer? Selecting clinical quality indicators for an Australian Brain Cancer Registry

BACKGROUND

The goal of a clinical quality registry is to deliver immediate gains in survival and quality of life by delivering timely feedback to practitioners, thereby ensuring every patient receives the best existing treatment. We are developing an Australian Brain Cancer Registry (ABCR) to identify, describe, and measure the impact of the variation and gaps in brain cancer care from the time of diagnosis to the end of life.

METHODS

To determine a set of clinical quality indicators (CQIs) for the ABCR, a database and internet search were used to identify relevant guidelines, which were then assessed for quality using the AGREE II Global Rating Scale. Potential indicators were extracted from 21 clinical guidelines, ranked using a modified Delphi process completed in 2 rounds by a panel of experts and other stakeholders, and refined by a multidisciplinary Working Group.

RESULTS

Nineteen key quality reporting domains were chosen, specified by 57 CQIs detailing the specific inclusion and outcome characteristics to be reported.

CONCLUSION

The selected CQIs will form the basis for the ABCR, provide a framework for achievable data collection, and specify best practices for patients and health care providers, with a view to improving care for brain cancer patients. To our knowledge, the systematic and comprehensive approach we have taken is a world first in selecting the reporting specifications for a brain cancer clinical registry.

The Role of Graphene Oxide Nanocarriers in Treating Gliomas

Gliomas are the most common primary malignant tumors of the central nervous system, and their conventional treatment involves maximal safe surgical resection combined with radiotherapy and temozolomide chemotherapy; however, this treatment does not meet the requirements of patients in terms of survival and quality of life. Graphene oxide (GO) has excellent physical and chemical properties and plays an important role in the treatment of gliomas mainly through four applications, viz. direct killing, drug delivery, immunotherapy, and phototherapy. This article reviews research on GO nanocarriers in the treatment of gliomas in recent years and also highlights new ideas for the treatment of these tumors.

[Comparative analysis of 5-ALA and chlorin E6 fluorescence-guided navigation in malignant glioma surgery]

OBJECTIVE

To analyze specificity and sensitivity of 5-ALA and chlorin E6 fluorescence-guided navigation in malignant glioma surgery.

MATERIAL AND METHODS

Fluorescence-guided navigation was analyzed in 50 patients (2 groups) with high-grade glioma. All patients were treated at the Polenov Russian Neurosurgery Institute. Chlorin E6 1 mg/kg intravenously (Photoditazin) was used as a fluorescence inducer in 25 patients (the 1st group), 5-ALA 20 mg/kg orally (Alasens) - in other 25 patients (the 2nd group). Each group included 10 patients with glioma grade III and 15 patients with glioma grade IV. Both groups were statistically representative (p>0.05).

RESULTS

In patients with glioma grade III, sensitivity of chlorin E6 fluorescence-guided navigation was 83.8%, 5-ALA fluorescence - 82.5%. Specificity was 66.7% and 64.1%, respectively. In patients with glioma grade IV, sensitivity was 87.7% for chlorin E6 and 88.3% for 5-ALA. Specificity was 85.2% and 88.1%, respectively.

CONCLUSION

Statistical analysis confirmed comparable high efficacy of both agents in surgery of malignant gliomas. Sensitivity and specificity of fluorescence-guided navigation with chlorin E6 and 5-ALA were similar (p>0.05).

Cetuximab-Ag2S quantum dots for fluorescence imaging and highly effective combination of ALA-based photodynamic/chemo-therapy of colorectal cancer cells

Colorectal cancer (CRC) has a poor prognosis and urgently needs better therapeutic approaches. 5-Aminolevulinic acid (ALA) induced protoporphyrin IX (PpIX) based photodynamic therapy (PDT) is already used in the clinic for several cancers but not yet well investigated for CRC. Currently, systemic administration of ALA offers a limited degree of tumour selectivity, except for intracranial tumours, limiting its wider use in the clinic. The combination of effective ALA-PDT and chemotherapy may provide a promising alternative approach for CRC treatment. Herein, theranostic Ag₂S quantum dots (AS-2MPA) optically trackable in near-infrared (NIR), conjugated with endothelial growth factor receptor (EGFR) targeting Cetuximab (Cet) and loaded with ALA for PDT monotherapy or ALA/5-fluorouracil (5FU) for the combination therapy are proposed for enhanced treatment of EGFR(+) CRC. AS-2MPA-Cet exhibited excellent targeting of the high EGFR expressing cells and showed a strong intracellular signal for NIR optical detection in a comparative study performed on SW480, HCT116, and HT29 cells, which exhibit high, medium and low EGFR expression, respectively. Targeting provided enhanced uptake of the ALA loaded nanoparticles by strong EGFR expressing cells and formation of higher levels of PpIX. Cells also differ in their efficiency to convert ALA to PpIX, and SW480 was the best, followed by HT29, while HCT116 was determined as unsuitable for ALA-PDT. The therapeutic efficacy was evaluated in 2D cell cultures and 3D spheroids of SW480 and HT29 cells using AS-2MPA with either electrostatically loaded, hydrazone or amide linked ALA to achieve different levels of pH or enzyme sensitive release. Most effective phototoxicity was observed in SW480 cells using AS-2MPA-ALA-electrostatic-Cet due to enhanced uptake of the particles, fast ALA release and effective ALA-to-PpIX conversion. Targeted delivery reduced the effective ALA concentration significantly which was further reduced with codelivery of 5FU. Delivery of ALA via covalent linkages was also effective for PDT, but required a longer incubation time for the release of ALA in therapeutic doses. Phototoxicity was correlated with high levels of reactive oxygen species (ROS) and apoptotic/necrotic cell death. Hence, both AS-2MPA-ALA-Cet based PDT and AS-2MPA-ALA-Cet-5FU based chemo/PDT combination therapy coupled with strong NIR tracking of the nanoparticles demonstrate an exceptional therapeutic effect on CRC cells and excellent potential for synergistic multistage tumour targeting therapy.

[Intraoperative fluorescence control with chlorin E6 in resection of glial brain tumors]

In recent years, fluorescence navigation has been increasingly used in surgery for gliomas. In most studies, 5-ALA derivatives are used as fluorescence inducers. However, there are few data regarding E6 chlorin for these purposes.

OBJECTIVE

To evaluate an effectiveness and feasibility of fluorescence navigation with chlorin E6 in surgery of brain gliomas.

MATERIAL AND METHODS

The study included 30 patients with glial brain tumors grade II-IV. All patients were operated at the Polenov Russian Neurosurgical Institute. We used surgical microscope (Leica OHS-1), D-Light AF System (Karl Storz, Germany), original fluorescence module (St. Petersburg LOMO, developed by G.V. Papayan) and special software RSS Cam - Endo 1.4.313 for visual analysis of fluorescence. Histological examination included hematoxylin-eosin staining of specimens and immunohistochemical studies.

RESULTS

Fluorescence was weak in all patients with Grade II gliomas and strong in almost all patients with Grade III-IV gliomas. Sensitivity of fluorescence diagnosis with chlorin E6 was 72.2% for Grade II gliomas, 83.8% for Grade III gliomas and 87.7% for Grade IV. Specificity of this method was 60% for Grade II gliomas, 66.7% for Grade III gliomas and 85.2% for Grade IV.

CONCLUSION

Certain method of fluorescence imaging ensured resection of glial brain tumors using chlorin E6. Intensity of tumor fluorescence correlated with glioma malignancy grade. These results indicate that chlorin E6 is an effective photosensitizer for intraoperative fluorescence diagnosis in surgery for glioma.

Evaluation of a Novel Three-Dimensional Robotic Digital Microscope (Aeos) in Neurosurgery

OBJECTIVE

Current literature debates the role of newly developed three-dimensional (3D) Exoscopes in the daily routine of neurosurgical practice. So far, only a small number of cadaver lab studies or case reports have examined the novel Aesculap Aeos Three-Dimensional Robotic Digital Microscope. This study aims to evaluate the grade of satisfaction and intraoperative handling of this novel system in neurosurgery.

METHODS

Nineteen neurosurgical procedures (12 cranial, 6 spinal and 1 peripheral nerve) performed over 9 weeks using the Aeos were analyzed. Ten neurosurgeons of varying levels of training were included after undergoing device instruction and training. Following every surgery, a questionnaire consisting of 43 items concerning intraoperative handling was completed. The questionnaires were analyzed using descriptive statistics.

RESULTS

No intraoperative complications occurred. Surgical satisfaction was ranked high (78.95%). In total, 84.21% evaluated surgical ergonomics as satisfactory, while 78.95% of the surgeons would like to use this system frequently. Image quality, independent working zoom function and depth of field were perceived as suboptimal by several neurosurgeons.

CONCLUSION

The use of Aeos is feasible and safe in microsurgical procedures, and surgical satisfaction was ranked high among most neurosurgeons in our study. The system might offer advanced ergonomic conditions in comparison to conventional ocular-based microscopes.

Therapeutic Potential of Berberine in the Treatment of Glioma: Insights into Its Regulatory Mechanisms

Glioma is known as one of the most common primary intracranial tumors accounting for four-fifths of malignant brain tumors. There are several biological pathways that play a synergistic, pathophysiological role in glioma, including apoptosis, autophagy, oxidative stress, and cell cycle arrest. According to previous rese arches, the drugs used in the treatment of glioma have been associated with significant limitations. Therefore, improved and/or new therapeutic platforms are required. In this regard, multiple flavonoids and alkaloids have been extensively studied in the treatment of glioma. Berberine is a protoberberine alkaloid with wide range of pharmacological activities, applicable to various pathological conditions. Few studies have reported beneficial roles of berberine in glioma. Berberine exerts its pharmacological functions in glioma by controlling different molecular and cellular pathways. We reviewed the existing knowledge supporting the use of berberine in the treatment of glioma and its effects on molecular and cellular mechanisms.

Stimulated Raman Histology for Rapid Intraoperative Diagnosis of Gliomas

BACKGROUND

Intraoperative pathologic diagnosis traditionally involves frozen section histopathology, which may be labor and time intensive. Indeed, a technique that streamlines the acquisition and evaluation of intraoperative histologic data may expedite surgical decision-making and shorten operative time. Stimulated Raman histology (SRH) is an emerging technology that allows for more rapid acquisition and interpretation of intraoperative histopathologic data.

METHODS

A blinded, prospective cohort study was performed for 82 patients undergoing resection for a central nervous system tumor. Of these, 21 patients were diagnosed with glioma either intraoperatively or postoperatively on permanent section histology and included in this study. Time to diagnosis (TTD) and diagnostic accuracy relative to permanent section (the gold standard) were compared between SRH-based diagnosis and conventional frozen section histology. Diagnostic concordance with permanent section was also compared between frozen histopathology and SRH diagnosis.

RESULTS

Diagnostic accuracy was not significantly different between methods (P = 1.00). Diagnostic concordance was not significantly different between methods when comparing 95% confidence intervals for kappa values (κ = 0.215; κ = 0.297; κ = 0.369). Lastly, mean TTD was significantly shorter with SRH-based diagnosis compared with frozen section (43 vs. 9.7 minutes, P < 0.0001). SRH was able to identify key features associated with varying glioma types.

CONCLUSIONS

SRH allows for rapid intraoperative diagnosis without sacrificing diagnostic accuracy. SRH may serve as a promising adjuvant to conventional histopathology to expedite intraoperative pathology consultation and surgical decision-making.

Heme Biosynthesis mRNA Expression Signature: Towards a Novel Prognostic Biomarker in Patients with Diffusely Infiltrating Gliomas

Simple Summary

Diffusely infiltrating gliomas are frequent brain tumors with variable prognosis. In addition to the blood pigment’s role of oxygen transportation, the metabolic pathway synthesizing heme has been shown to play a role in the biochemistry of various tumors. In this study we thus investigated the impact of heme biosynthesis factors mRNA expression on the survival in glioma patients and observed a progressive decrease in survival time with increasing mRNA expression signature. This association was present for overall as well as progression-free survival and remained statistically significant after correction for established prognostic factors such as patient age and tumor grade.

Abstract

Diffusely infiltrating gliomas are characterized by a variable clinical course, and thus novel prognostic biomarkers are needed. The heme biosynthesis cycle constitutes a fundamental metabolic pathway and might play a crucial role in glioma biology. The aim of this study was thus to investigate the role of the heme biosynthesis mRNA expression signature on prognosis in a large glioma patient cohort. Glioma patients with available sequencing data on heme biosynthesis expression were retrieved from The Cancer Genome Atlas (TCGA). In each patient, the heme biosynthesis mRNA expression signature was calculated and categorized into low, medium, and high expression subgroups. Differences in progression-free and overall survival between these subgroups were investigated including a multivariate analysis correcting for WHO grade, tumor subtype, and patient age and sex. In a total of 693 patients, progression-free and overall survival showed a strictly monotonical decrease with increasing mRNA expression signature subgroups. In detail, median overall survival was 134.2 months in the low, 79.9 months in the intermediate, and 16.5 months in the high mRNA expression signature subgroups, respectively. The impact of mRNA expression signature on progression-free and overall survival was independent of the other analyzed prognostic factors. Our data indicate that the heme biosynthesis mRNA expression signature might serve as an additional novel prognostic marker in patients with diffusely infiltrating gliomas to optimize postoperative management.

Management, functional outcomes and survival in a French multicentric series of 118 adult patients with cerebellar glioblastoma

PURPOSE

To analyze the outcomes and predictors in a large series of cerebellar glioblastomas in order to guide patient management.

METHODS

The French brain tumor database and the Club de Neuro-Oncologie of the Société Française de Neurochirurgie retrospectively identified adult patients with cerebellar glioblastoma diagnosed between 2003 and 2017. Diagnosis was confirmed by a centralized neuropathological review.

RESULTS

Data from 118 cerebellar glioblastoma patients were analyzed (mean age 55.9 years, 55.1% males). The clinical presentation associated raised intracranial pressure (50.8%), static cerebellar syndrome (68.6%), kinetic cerebellar syndrome (49.2%) and/or cranial nerve disorders (17.8%). Glioblastomas were hemispheric (55.9%), vermian (14.4%) or both (29.7%). Hydrocephalus was present in 49 patients (41.5%). Histologically, tumors corresponded either to IDH-wild-type or to K27-mutant glioblastomas. Surgery consisted of total (12.7%), subtotal (35.6%), partial resection (33.9%) or biopsy (17.8%). The postoperative Karnofsky performance status was improved, stable and worsened in 22.4%, 43.9% and 33.7% of patients, respectively. Progression-free and overall survivals reached 5.1 months and 9.1 months, respectively. Compared to other surgical strategies, total or subtotal resection improved the Karnofsky performance status (33.3% vs 12.5%, p < 0.001), prolonged progression-free and overall survivals (6.5 vs 4.3 months, p = 0.015 and 16.7 vs 6.2 months, p < 0.001, respectively) and had a comparable complication rate (40.4% vs 31.1%, p = 0.29). After total or subtotal resection, the functional outcomes were correlated with age (p = 0.004) and cerebellar hemispheric tumor location (p < 0.001) but not brainstem infiltration (p = 0.16).

CONCLUSION

In selected patients, maximal resection of cerebellar glioblastoma is associated with improved onco-functional outcomes, compared with less invasive procedures.

Capability of physically reasonable OCT-based differentiation between intact brain tissues, human brain gliomas of different WHO grades, and glioma model 101.8 from rats

Optical coherence tomography (OCT) of the ex vivo rat and human brain tissue samples is performed. The set of samples comprises intact white and gray matter, as well as human brain gliomas of the World Health Organization (WHO) Grades I-IV and glioma model 101.8 from rats. Analysis of OCT signals is aimed at comparing the physically reasonable properties of tissues, and determining the attenuation coefficient, parameter related to effective refractive index, and their standard deviations. Data analysis is based on the linear discriminant analysis and estimation of their dispersion in a four-dimensional principal component space. The results demonstrate the distinct contrast between intact tissues and low-grade gliomas and moderate contrast between intact tissues and high-grade gliomas. Particularly, the mean values of attenuation coefficient are 7.56±0.91, 3.96±0.98, and 5.71±1.49 mm-1 for human white matter, glioma Grade I, and glioblastoma, respectively. The significant variability of optical properties of high Grades and essential differences between rat and human brain tissues are observed. The dispersion of properties enlarges with increase of the glioma WHO Grade, which can be attributed to the growing heterogeneity of pathological brain tissues. The results of this study reveal the advantages and drawbacks of OCT for the intraoperative diagnosis of brain gliomas and compare its abilities separately for different grades of malignancy. The perspective of OCT to differentiate low-grade gliomas is highlighted by the low performance of the existing intraoperational methods and instruments.

5-Aminolevulinic acid tumor paint and photodynamic therapy for myxofibrosarcoma: an in vitro study

Background

5-Aminolevulinic acid (5-ALA), a fluorescent contrast agent, has been used for tumor paint and photodynamic therapy (PDT) for various tumors, but its use with soft tissue sarcomas is not well documented. Myxofibrosarcoma, a subtype of soft tissue sarcoma with a high local recurrence rate, may benefit from similar types of treatment. The purpose of this study was to analyze the effects of 5-ALA tumor paint and PDT on a myxofibrosarcoma cell line.

Methods

Tumor paint was assessed by exposing micromass pellets of human adipose-derived stromal (ADS) cells or myxofibrosarcoma (MUG-Myx1) cells to 5-ALA. Cell pellets were then visualized using a microscope at established excitation and emission wavelengths. Corrected total cell fluorescence was calculated per accepted protocols. Photodynamic therapy was similarly assessed by exposing ADS and MUG-Myx1 cells to 5-ALA, with subsequent analysis via flow cytometry and real-time confocal microscopy.

Results

The use of 5-ALA tumor paint led to a selective fluorescence in MUG-Myx1 cells. Findings were confirmed by flow cytometry. Interestingly, flow cytometry results showed progressive selective cell death with increasing 5-ALA exposure as a result of the PDT effect. PDT was further confirmed using confocal microscopy, which revealed progressive cellular bubble formation consistent with advancing stages of cell death—a finding that was not seen in control ADS cells.

Conclusions

5-ALA tumor paint and PDT were successfully used on a human myxofibrosarcoma cell line (MUG-Myx1). Results from this study showed both selective fluorescent tagging and selective cytotoxicity of 5-ALA toward malignant myxofibrosarcoma cells, while sparing benign adipose control cells. This finding was further confirmed in a dramatic time-lapse video, visually confirming active, targeted cell death. 5-ALA’s two-pronged application of selective tumor identification and cytotoxicity may transform surgical and medical approaches for treating soft tissue sarcomas.