Improving the extent of malignant glioma resection by dual intraoperative visualization approach

Neural Progenitor Cell-Mediated Magnetic Nanoparticles for Magnetic Resonance Imaging and Photothermal Therapy of Glioma

Glioma is the most common primary malignant tumor in the brain. The diagnostic accuracy and treatment efficiency of glioma are facing great challenges due to the presence of the blood-brain barrier (BBB) and the high infiltration of glioma. There is an urgent need to explore the combination of diagnostic and therapeutic approaches to achieve a more accurate diagnosis, as well as guidance before and after surgery. In this work, we induced human induction of pluripotent stem cell into neural progenitor cells (NPCs) and synthesized nanoprobes labeled with enhanced green fluorescent protein (EGFP, abbreviated as MFe3O4-labeled EGFP-NPCs) for photothermal therapy. Nanoprobes carried by NPCs can effectively penetrate the BBB and target glioma for the purpose of magnetic resonance imaging and guiding surgery. More importantly, MFe3O4-labeled EGFP-NPCs can effectively induce local photothermal therapy, conduct preoperative tumor therapy, and inhibit the recurrence of postoperative glioma. This work shows that MFe3O4-labeled EGFP-NPCs is a promising nanoplatform for glioma diagnosis, accurate imaging-guided surgery, and effective photothermal therapy.

Fluorescence visualization for cancer DETECTION: EXPERIENCE and perspectives

The current review focuses on the latest advances in the improvement and application of fluorescence imaging technology. Near-infrared (NIR) fluorescence imaging is a promising new technique that uses non-specific fluorescent agents and targeted fluorescent tracers combined with a dedicated camera to better navigate and visualize tumors. Fluorescence-guided surgery (FGS) is used to perform various tasks, helping the surgeon to distinguish lymphatic vessels and nodes from surrounding tissues easily and quickly assess the perfusion of the planned resection area, including intraoperative visualization of metastases. The results of the insertion of fluorescence visualization as an auxiliary method to cancer detection and high-risk metastatic lesions in clinical practice have demonstrated enthusiastic results and huge potential. However, intraoperative fluorescence visualization must not be considered as a main diagnostic or treatment method but as an aid to the surgeon. Thus, fluorescence study does not dispense the diagnostic gold standards of benign or malignant tumors (conventional examination, biopsy, ultrasonography and computed tomography, etc.) and can be done usually during intraoperative treatment. Moreover, as fluorescence surgery and fluorescence diagnostic techniques continue to improve, it is likely that they will evolve towards targeted fluorescence imaging probes that will increasingly target a specific type of cancer cell. The most important point remains the search for highly selective messengers of fluorescent labels, which make it possible to identify tumor cells exclusively in the affected organs and indicate to surgeons the boundaries of their spread and metastasis.

Novel intraoperative strategies for enhancing tumor control: Future directions

Maximal safe surgical resection plays a key role in the care of patients with gliomas. A range of technologies have been developed to aid surgeons in distinguishing tumor from normal tissue, with the goal of increasing tumor resection and limiting postoperative neurological deficits. Technologies that are currently being investigated to aid in improving tumor control include intraoperative imaging modalities, fluorescent tumor makers, intraoperative cell and molecular profiling of tumors, improved microscopic imaging, intraoperative mapping, augmented and virtual reality, intraoperative drug and radiation delivery, and ablative technologies. In this review, we summarize the aforementioned advancements in neurosurgical oncology and implications for improving patient outcomes.

Surgical treatment of diffuse and multi-lobes involved glioma with the assistance of a multimodal technique

Diffuse and multi-lobes involved glioma (DMG) is a rare disease, and the aim of this study was to assess the role of multimodal-assisted surgical resection of tumours combined with chemoradiotherapy and identify prognosis. Clinical data were collected from 38 patients with a diagnosis of DMG. Nineteen patients received multimodal-assisted surgical resection of tumours combined with chemoradiotherapy, and another 19 patients underwent chemoradiotherapy alone after stereotactic puncture biopsy. The clinical characteristics, magnetic resonance imaging (MRI) findings, histopathological diagnosis, progression-free survival, and overall survival of DMG patients were retrospectively analysed. Twenty-six males and 12 females were included, and the age of the participants ranged from 10 to 80 years (46.34 ± 15.61). The median overall survival in our study was 25 months, and the progression-free survival was 17 months. The extent of resection was 50.10–73.60% (62.54% ± 7.92%). The preoperative and the postoperative KPS score of the patients in the operation group showed no statistically significant difference. The results of logistic regression demonstrated that overall survival was positively associated with operative treatment + chemoradiotherapy (p = 0.003) but negatively associated with age and corpus callosal involvement (p = 0.028 and 0.022, respectively). Kaplan–Meier analyses showed that those who underwent surgical treatment had a significant progression-free and overall survival benefit compared to those who did not undergo surgical treatment (log-rank test; p = 0.011 and 0.008, respectively). Older age and involvement of the corpus callosum represent a poor prognosis in DMG patients. Multimodal-assisted surgical resection of tumours combined with chemoradiotherapy might be a treatment option for DMG. Further research is needed to obtain the clear evidence of the effect of surgical treatment.

5-Aminolevulinic Acid-Guided Resection in Grade III Tumors-A Comparative Cohort Study

BACKGROUND

The benefits of using 5-aminolevulinic acid (5-ALA) in resection of grade IV tumors have been extensively researched. However, few studies have investigated the use of 5-ALA in grade III gliomas.

OBJECTIVE

To discover whether 5-ALA provides significant benefit in assisting resection of grade III gliomas.

METHODS

A single-center, retrospective cohort study between January 2013 and January 2019 of adult patients with grade III gliomas. Patients were separated into a 5-ALA-guided surgery group (5-ALA-GS) and non-5-ALA-guided surgery group (non-5-ALA-GS). Primary outcome was overall survival (OS); secondary outcomes were both postoperative and 6-month performance status (PS6m), and extent of resection (EoR).

RESULTS

Sixty-nine patients with grade III gliomas were included (39 and 30 patients in the 5-ALA-GS group and non-5-ALA-GS group, respectively). There was no significant difference in tumor characteristics between the groups. No significant difference was observed in OS (P = .072) and EoR (P = .609) between both the groups. In a subgroup of the 5-ALA-GS where gross total resection (GTR) was achieved, there was a better OS (P = .043). Significantly worse outcomes were seen postoperatively (P = .044) and at PS6m (P = .041) in the 5-ALA-GS group, mainly because of the poorer outcome in the subtotal resection subgroup.

CONCLUSION

Despite the benefits of 5-ALA in grade IV glioma surgery, these benefits are limited to a smaller group of patients with grade III tumors where there is sufficient fluorescence to allow GTR. In this cohort of patients, 5-ALA use may result in worse neurological outcomes particularly when GTR is not feasible and therefore caution is warranted.

Combined Fluorescence-Guided Resection and Intracavitary Thermotherapy with Superparamagnetic Iron‐Oxide Nanoparticles for Recurrent High-Grade Glioma: Case Series with Emphasis on Complication Management

Simple Summary

Recurrent high-grade gliomas are difficult to treat. Here, we report on our single-center experience in combining fluorescence-guided tumor resection with 5-ALA and local thermotherapy with superparamagnetic iron nanoparticles. In total, 18 patients were operated on and received thermotherapy with or without additional radiotherapy. The median progression-free survival was 5.5 months and median overall survival was 9.5 months. Although no major side effects were observed during active treatment, 72% of the patients developed cerebral edema requiring steroid treatment or even surgical removal of the nanoparticles. In conclusion, the combination of fluorescence-guided resection and intracavitary thermotherapy provides a novel and promising treatment option for improving local tumor control in recurrent high-grade gliomas, but further refinements of the treatment protocol are needed to decrease major side effects.

Abstract

Background: Concepts improving local tumor control in high-grade glioma (HGG) are desperately needed. The aim of this study is to report an extended series of cases treated with a combination of 5-ALA-fluorescence-guided resection (FGR) and intracavitary thermotherapy with superparamagnetic iron oxide nanoparticles (SPION). Methods: We conducted a single-center retrospective review of all recurrent HGG treated with FGR and intracavitary thermotherapy (n = 18). Patients underwent six hyperthermia sessions in an alternating magnetic field and received additional adjuvant therapies on a case-by-case basis. Results: Nine patients were treated for first tumor recurrence; all other patients had suffered at least two recurrences. Nine patients received combined radiotherapy and thermotherapy. The median progression-free survival was 5.5 (95% CI: 4.67–6.13) months and median overall survival was 9.5 (95% CI: 7.12–11.79) months. No major side effects were observed during active treatment. Thirteen patients (72%) developed cerebral edema and more clinical symptoms during follow-up and were initially treated with dexamethasone. Six (33%) of these patients underwent surgical removal of nanoparticles due to refractory edema. Conclusions: The combination of FGR and intracavitary thermotherapy with SPION provides a new treatment option for improving local tumor control in recurrent HGG. The development of cerebral edema is a major issue requiring further refinements of the treatment protocol.

Intraoperative 5-ALA fluorescence-guided resection of high-grade glioma leads to greater extent of resection with better outcomes: a systematic review

IMPORTANCE

High-grade gliomas (HGG) are the most aggressive and common malignant brain tumors in adults. They have a dismally fatal prognosis. Even if gross total resection of the enhancing tumor is achieved, inevitably, invading tumor cells that are indistinguishable to the un-aided eye are left behind, which eventually leads to tumor recurrence. 5-aminolevulinic acid (5-ALA) is an increasingly utilized intraoperative fluorescent imaging agent for patients with HGG. It enhances visualization of HGG tissue. Despite early promising randomized clinical trial data suggesting a survival benefit for 5-ALA-guided surgery, the growing body of literature must be analyzed to confirm efficacy on patient outcomes.

OBJECTIVE

To perform a systematic review of the literature to evaluate whether there is a beneficial effect upon survival and extent of resection due to the utilization of 5-ALA in HGG surgery.

EVIDENCE REVIEW

Literature regarding 5-ALA usage in HGG surgery was reviewed according to the PRISMA guidelines. Two databases, PubMed and SCOPUS, were searched for assorted combinations of the keywords "5-ALA," "high-grade glioma," "5-aminolevulinic acid," and "resection" in July 2020 for case reports and retrospective, prospective, and randomized clinical trials assessing and analyzing 5-ALA intraoperative use in patients with HGG. Entailed studies on PubMed and SCOPUS were found for screening using a snowball search technique upon the initially searched papers. Systematic reviews and meta-analyses were excluded from our PRISMA table.

FINDINGS

3756 previously published studies were screened, 536 of which were further evaluated, and ultimately 45 were included in our systematic review. There were no date restrictions on the screened publications. Our literature search was finalized on July 16, 2020. We found an observed increase in the overall survival (OS) and progression-free survival (PFS) of the 5-ALA group compared to the white light group, as well as an observed increase in the OS and PFS of complete resections compared to incomplete resections. Of the studies that directly compared the use of 5-ALA to white light (13 of the total analyzed 45, or 28.9%), 5-ALA lead to a better PFS and OS in 88.4 and 67.5% of patients, respectively. When the studies that reported postoperative neurologic outcomes of surgeries using 5-ALA vs. white light were analyzed, 42.2% of subjects demonstrated 5-ALA use was associated with less post-op neurological deficits, whereas 34.5% demonstrated no difference between 5-ALA and without. 23.3% of studies showed that intraoperative 5-ALA guided surgeries lead to more post-op neurological deficits.

CONCLUSIONS AND RELEVANCE

Utilization of 5-ALA was found to be associated with a greater extent of resection in HGG surgeries, as well as longer OS and PFS. Postop neurologic deficit rates were mixed and inconclusive when comparing 5-ALA groups to white light groups. 5-ALA is a useful surgical adjunct for resection of HGG when patient safety is preserved.

Macrophage-Mediated Porous Magnetic Nanoparticles for Multimodal Imaging and Postoperative Photothermal Therapy of Gliomas

Because of the blood-brain barrier and the high infiltration of glioma cells, the diagnostic accuracy and treatment efficiency of gliomas are still facing challenges. There is an urgent need to explore the integration of diagnostic and therapeutic methods to achieve an accurate diagnosis, guide surgery, and inhibit postoperative recurrence. In this work, we developed a macrophage loaded with a photothermal nanoprobe (MFe₃O₄-Cy5.5), which is able to cross the blood-brain barrier and accumulate into deep gliomas to achieve multimodal imaging and guided glioma surgery purposes. With desirable probing depth and high signal-to-noise ratio, Fe₃O₄-Cy5.5 can perform fluorescence, photoacoustic, and magnetic resonance imaging, which can distinguish brain tumors from the surrounding normal tissues and accurately guide glioma resection. Meanwhile, Fe₃O₄-Cy5.5 can effectively induce local photothermal therapy and inhibit the recurrence of glioma after surgery. These results demonstrate that the macrophage-mediated Fe₃O₄-Cy5.5, which can achieve a multimodal diagnosis, accurate imaging-guided surgery, and effective photothermal therapy, is a promising nanoplatform for gliomas.

A systematic review and meta-analysis of fluorescent-guided resection and therapy-based photodynamics on the survival of patients with glioma

Glioma is the most common primary central nervous system tumor; many methods are currently being used to research and treat glioma. In recent years, fluorescent-guided resection (FGR) and photodynamic therapy (PDT) have become hot spots in the treatment of glioma. Based on the existing literatures regarding the FGR enhancing resection rate and regarding efficacy of PDT for the treatment of glioma, this paper made a systematic review of FGR for gross total resection of patients and the PDT for the survival of patients with glioma. Meta-analysis of eligible studies was performed to derive precise estimation of PDT on the prognosis of patients with glioma by searching all related literatures in PubMed, EMBASE, Cochrane, and Web of Science databases, and further to evaluate (GTR) under FGR and the efficacy of PDT therapy, including 1-year and 2-year survival rates, overall survival (OS), and progression-free survival (PFS). According to the inclusion and exclusion criteria, a total of 1294 patients with glioma were included in the final analysis of 31 articles, among which a 73.00% (95% CI, 68.00 ~ 79.00%, P < 0.01) rate of GTR in 27 groups included in 23 articles was reported for those receiving FGR. The OS was 17.78 months (95% CI, 8.89 ~ 26.67, P < 0.01) in 5 articles on PDT-treated patients with glioma, and the mean difference of OS was 6.18 (95% CI, 3.3 ~ 9.06, P < 0.01) between PDT treatment and conventional glioma surgery, showing a statistically significant difference (P < 0.01). The PFS was 10.82 months (95% CI, 7.04 ~ 14.61, P < 0.01) in 5 articles on PDT-treated patients with glioma. A 1-year survival rate of 59.00% (95% CI, 38.00 ~ 77.00%, P < 0.01) in 10 groups included in 8 articles and 2-year survival rate of 25.00% (95% CI, 15.00 ~ 36.00%, P < 0.01) in 7 groups included in 6 articles were reported for those with PDT. FGR and PDT are feasible for treatment of patients with glioma, because FGR can effectively increase the resection rate, at the same time, PDT can prolong the survival time. However, due to the limitation of small sample size in the existing studies, larger samples and randomized controlled clinical trials are needed to analyze the resection under FGR and efficacy of PDT in patients with glioma.

5-Aminolevulinic Acid-Shedding Light on Where to Focus

BACKGROUND

Surgical management of gliomas is predicated on "safe maximal resection" across all histopathologic grades because progression-free survival and overall survival are positively affected by the increasing extent of resection. Administration of the prodrug 5-aminolevulinic acid (5-ALA) induces tumor fluorescence with high specificity and sensitivity for malignant high-grade glioma (HGG). Fluorescence-guided surgery (FGS) using 5-ALA improves the extent of resection in the contrast-enhancing and nonenhancing tumor components in HGG. It has also shown preliminary usefulness in other central nervous system tumors, but with certain limitations.

METHODS

We review and discuss the state of 5-ALA FGS for central nervous system tumors and identify the limitations in its use as a guide for future clinical optimization.

RESULTS

5-ALA FGS provides maximum clinical benefits in the treatment of newly diagnosed glioblastoma. 5-ALA fluorescence specificity is limited in low-grade glioma, recurrent HGG, and non-glial tumors. Several promising intraoperative adjuncts to 5-ALA FGS have been developed to expand its indications and improve the clinical efficacy and usefulness of 5-ALA FGS.

CONCLUSIONS

5-ALA FGS improves the clinical outcomes in HGG. However, further optimization of the diagnostic performance and clinical use of 5-ALA FGS is necessary for low-grade glioma and recurrent HGG tumors. Neurosurgical oncology will benefit from the novel use of advanced technologies and intraoperative visualization techniques outlined in this review, such as machine learning, hand-held fibe-optic probes, augmented reality, and three-dimensional exoscope assistance, to optimize the clinical usefulness and operative outcomes of 5-ALA FGS.

Current Limitations of Intraoperative Ultrasound in Brain Tumor Surgery

While benefits of intraoperative ultrasound (IOUS) have been frequently described, data on IOUS limitations are relatively sparse. Suboptimal ultrasound imaging of some pathologies, various types of ultrasound artifacts, challenging patient positioning during some IOUS-guided surgeries, and absence of an optimal IOUS probe depicting the entire sellar region during transsphenoidal pituitary surgery are some of the most important pitfalls. This review aims to summarize prominent limitations of current IOUS systems, and to present possibilities to reduce them by using ultrasound technology suitable for a specific procedure and by proper scanning techniques. In addition, future trends of IOUS imaging optimization are described in this article.

Brain Mapping-Aided SupraTotal Resection (SpTR) of Brain Tumors: The Role of Brain Connectivity

Brain gliomas require a deep knowledge of their effects on brain connectivity. Understanding the complex relationship between tumor and functional brain is the preliminary and fundamental step for the subsequent surgery. The extent of resection (EOR) is an independent variable of surgical effectiveness and it correlates with the overall survival. Until now, great efforts have been made to achieve gross total resection (GTR) as the standard of care of brain tumor patients. However, high and low-grade gliomas have an infiltrative behavior and peritumoral white matter is often infiltrated by tumoral cells. According to these evidences, many efforts have been made to push the boundary of the resection beyond the contrast-enhanced lesion core on T1w MRI, in the so called supratotal resection (SpTR). SpTR is aimed to maximize the extent of resection and thus the overall survival. SpTR of primary brain tumors is a feasible technique and its safety is improved by intraoperative neuromonitoring and advanced neuroimaging. Only transient cognitive impairments have been reported in SpTR patients compared to GTR patients. Moreover, SpTR is related to a longer overall and progression-free survival along with preserving neuro-cognitive functions and quality of life.

Intraoperative MRI versus 5-ALA in high-grade glioma resection: a network meta-analysis

OBJECTIVE

High-grade gliomas (HGGs) continue to carry poor prognoses, and patient outcomes depend heavily on the extent of resection (EOR). The utility of conventional image-guided surgery is limited by intraoperative brain shift. More recent techniques to maximize EOR, including intraoperative imaging and the use of fluorescent dyes, combat these limitations. However, the relative efficacy of these two techniques has never been systematically compared. Thus, the authors performed an exhaustive systematic review in conjunction with quantitative network meta-analyses to evaluate the comparative effectiveness of 5-aminolevulinic acid (5-ALA) and intraoperative MRI (IMRI) in optimizing EOR in HGG. They secondarily analyzed associated progression-free and overall survival and performed subgroup analyses by level of evidence.

METHODS

PubMed, Embase, Cochrane Central, and Web of Science were searched for studies evaluating conventional neuronavigation, IMRI, and 5-ALA in HGG resection. The primary study endpoint was the proportion of patients attaining gross-total resection (GTR), defined as 100% elimination of contrast-enhancing lesion on postoperative MRI. Secondary endpoints included overall and progression-free survival and subgroup analyses for level of evidence. Comparative efficacy analysis of IMRI and 5-ALA was performed using Bayesian network meta-analysis models.

RESULTS

This analysis included 11 studies. In a classic meta-analysis, both IMRI (OR 4.99, 95% CI 2.65-9.39, p < 0.001) and 5-ALA (OR 2.866, 95% CI 2.127-3.863, p < 0.001) were superior to conventional navigation in achieving GTR. Bayesian network analysis was employed to indirectly compare IMRI to 5-ALA, and no significant difference in GTR was found between the two (OR 1.9 favoring IMRI, 95% CI 0.905-3.989, p = 0.090). A handful of studies additionally suggested that the use of either IMRI (2 and 4 studies, respectively) or 5-ALA (2 and 2 studies, respectively) improves progression-free and overall survival.

CONCLUSIONS

IMRI and 5-ALA are individually superior to conventional neuronavigation for achieving GTR of HGG. Between IMRI and 5-ALA, neither method is clearly more effective. Future studies evaluating the comparative cost and surgical time associated with IMRI and 5-ALA will better inform any cost-benefit analysis.

Cerebral microcirculation in glioblastoma: A major determinant of diagnosis, resection, and drug delivery

Glioblastoma (GBM) is the most common primary brain tumor with a dismal prognosis. Current standard of treatment is safe maximal tumor resection followed by chemotherapy and radiation. Altered cerebral microcirculation and elevated blood-tumor barrier (BTB) permeability in tumor periphery due to glioma-induced vascular dysregulation allow T1 contrast-enhanced visualization of resectable tumor boundaries. Newer tracers that label the tumor and its vasculature are being increasingly used for intraoperative delineation of glioma boundaries for even more precise resection. Fluorescent 5-aminolevulinic acid (5-ALA) and indocyanine green (ICG) are examples of such intraoperative tracers. Recently, magnetic resonance imaging (MRI)-based MR thermometry is being employed for laser interstitial thermal therapy (LITT) for glioma debulking. However, aggressive, fatal recurrence always occurs. Postsurgical chemotherapy is hampered by the inability of most drugs to cross the blood-brain barrier (BBB). Understanding postsurgical changes in brain microcirculation and permeability is crucial to improve chemotherapy delivery. It is important to understand whether any microcirculatory indices can differentiate between true recurrence and radiation necrosis. LITT leads to peri-ablation BBB opening that persists for several weeks. Whether it can be a conduit for chemotherapy delivery is yet to be explored. This review will address the role of cerebral microcirculation in such emerging ideas in GBM diagnosis and therapy.

Real-Time Fluorescence Image-Guided Oncolytic Virotherapy for Precise Cancer Treatment

Oncolytic virotherapy is one of the most promising, emerging cancer therapeutics. We generated three types of telomerase-specific replication-competent oncolytic adenovirus: OBP-301; a green fluorescent protein (GFP)-expressing adenovirus, OBP-401; and Killer-Red-armed OBP-301. These oncolytic adenoviruses are driven by the human telomerase reverse transcriptase (hTERT) promoter; therefore, they conditionally replicate preferentially in cancer cells. Fluorescence imaging enables visualization of invasion and metastasis in vivo at the subcellular level; including molecular dynamics of cancer cells, resulting in greater precision therapy. In the present review, we focused on fluorescence imaging applications to develop precision targeting for oncolytic virotherapy. Cell-cycle imaging with the fluorescence ubiquitination cell cycle indicator (FUCCI) demonstrated that combination therapy of an oncolytic adenovirus and a cytotoxic agent could precisely target quiescent, chemoresistant cancer stem cells (CSCs) based on decoying the cancer cells to cycle to S-phase by viral treatment, thereby rendering them chemosensitive. Non-invasive fluorescence imaging demonstrated that complete tumor resection with a precise margin, preservation of function, and prevention of distant metastasis, was achieved with fluorescence-guided surgery (FGS) with a GFP-reporter adenovirus. A combination of fluorescence imaging and laser ablation using a KillerRed-protein reporter adenovirus resulted in effective photodynamic cancer therapy (PDT). Thus, imaging technology and the designer oncolytic adenoviruses may have clinical potential for precise cancer targeting by indicating the optimal time for administering therapeutic agents; accurate surgical guidance for complete resection of tumors; and precise targeted cancer-specific photosensitization.

Characteristics of Fluorescent Intraoperative Dyes Helpful in Gross Total Resection of High-Grade Gliomas-A Systematic Review

Background: A very important aspect in the treatment of high-grade glioma is gross total resection to reduce the risk of tumor recurrence. One of the methods to facilitate this task is intraoperative fluorescence navigation. The aim of the study was to compare the dyes used in this technique fluorescent intraoperative navigation in terms of the mechanism of action and influence on the treatment of patients. Methods: The review was carried out on the basis of articles found in PubMed, Google Scholar, and BMC search engines, as well as those identified by searched bibliographies and suggested by experts during the preparation of the article. The database analysis was performed for the following phrases: "glioma", "glioblastoma", "ALA", "5ALA", "5-ALA", "aminolevulinic acid", "levulinic acid", "fluorescein", "ICG", "indocyanine green", and "fluorescence navigation". Results: After analyzing 913 citations identified on the basis of the search criteria, we included 36 studies in the review. On the basis of the analyzed articles, we found that 5-aminolevulinic acid and fluorescein are highly effective in improving the percentage of gross total resection achieved in high-grade glioma surgery. At the same time, the limitations resulting from the use of these methods are marked-higher costs of the procedure and the need to have neurosurgical microscope in combination with a special light filter in the case of 5-aminolevulinic acid (5-ALA), and low specificity for neoplastic cells and the dependence on the degree of damage to the blood-brain barrier in the intensity of fluorescence in the case of fluorescein. The use of indocyanine green in the visualization of glioma cells is relatively unknown, but some researchers have suggested its utility and the benefits of using it simultaneously with other dyes. Conclusion: The use of intraoperative fluorescence navigation with the use of 5-aminolevulinic acid and fluorescein allows the range of high-grade glioma resection to be increased.

Aggressive Treatment in Glioblastoma: What Determines the Survival of Patients?

BACKGROUND AND STUDY AIMS

 The exact reason of long-term survival in glioblastoma (GBM) patients has remained uncertain. Molecular parameters in addition to histology to define malignant gliomas are hoped to facilitate clinical, experimental, and epidemiological studies.

MATERIAL AND METHODS

 A population of GBM patients with similar clinical characteristics (especially similar resectability) was reviewed to compare the molecular variables between poor (overall survival [OS] < 18 months, control cohort) and long-term survivors (overall survival > 36 months, OS-36 cohort).

RESULTS

 Long-term GBM survivors were younger. In the OS-36 cohort, the positive rate of isocitrate dehydrogenase (IDH) mutation was very low (7.69%, 3/39) and there was no statistical difference in OS between IDH mutant and wild-type patients. The results of 1p/19q codeletions are similar. Besides, there were no significant difference in MGMT promoter methylation, telomerase reverse transcriptase (TERT) promoter mutation, and TP53 mutations between OS-36 cohort and control cohort.

CONCLUSIONS

 No distinct markers consistently have been identified in long-term survivors of GBM patients, and great importance should be attached to further understand the biological characteristics of the invasive glioma cells because of the nature of diffuse tumor permeation.

Heterogeneity Matters: Different Regions of Glioblastoma Are Characterized by Distinctive Tumor-Supporting Pathways

Simple Summary

5-ALA Fluorescence Guided Surgery aims at extending the boundaries of glioblastoma (GBM) resection. It is based on the use of a fluorescent dye, 5-aminolevulinic acid (5-ALA). Depending on the fluorescence levels, it is possible to distinguish the core of the tumor, the infiltrating borders and the healthy tissue. Since GBM progression is supported by tumor cells and their interaction with the surrounding microenvironment, we hypothesized that 5-ALA intensity could identify microenvironments with different tumor supporting properties. Taking advantage of glioma-associated stem cells; a human in vitro model of the glioma microenvironment, we demonstrate that all regions of the tumor support the tumor growth, but through different pathways. This study highlights the importance of understanding the TME to obtain key information on GBM biology and develop new therapeutic approaches.

Abstract

The glioblastoma microenvironment plays a substantial role in glioma biology. However, few studies have investigated its spatial heterogeneity. Exploiting 5-ALA Fluorescence Guided Surgery (FGS), we were able to distinguish between the tumor core (ALA+), infiltrating area (ALA-PALE) and healthy tissue (ALA−) of the glioblastoma, based on the level of accumulated fluorescence. The aim of this study was to investigate the properties of the microenvironments associated with these regions. For this purpose, we isolated glioma-associated stem cells (GASC), resident in the glioma microenvironment, from ALA+, ALA-PALE and ALA− samples and compared them in terms of growth kinetic, phenotype and for the expression of 84 genes associated with cancer inflammation and immunity. Differentially expressed genes were correlated with transcriptomic datasets from TCGA/GTEX. Our results show that GASC derived from the three distinct regions, despite a similar phenotype, were characterized by different transcriptomic profiles. Moreover, we identified a GASC-based genetic signature predictive of overall survival and disease-free survival. This signature, highly expressed in ALA+ GASC, was also well represented in ALA PALE GASC. 5-ALA FGS allowed to underline the heterogeneity of the glioma microenvironments. Deepening knowledge of these differences can contribute to develop new adjuvant therapies targeting the crosstalk between tumor and its supporting microenvironment.

Intraoperative fluorescence diagnosis in the brain: a systematic review and suggestions for future standards on reporting diagnostic accuracy and clinical utility

Background

Surgery for gliomas is often confounded by difficulties in distinguishing tumor from surrounding normal brain. For better discrimination, intraoperative optical imaging methods using fluorescent dyes are currently being explored. Understandably, such methods require the demonstration of a high degree of diagnostic accuracy and clinical benefit. Currently, clinical utility is determined by tissue biopsies which are correlated to optical signals, and quantified using measures such as sensitivity, specificity, positive predictive values, and negative predictive values. In addition, surgical outcomes, such as extent of resection rates and/or survival (progression-free survival (PFS) and overall survival (OS)) have been measured. These assessments, however, potentially involve multiple biases and confounders, which have to be minimized to ensure reproducibility, generalizability and comparability of test results. Test should aim at having a high internal and external validity. The objective of this article is to analyze how diagnostic accuracy and outcomes are utilized in available studies describing intraoperative imaging and furthermore, to derive recommendations for reliable and reproducible evaluations.

Methods

A review of the literature was performed for assessing the use of measures of diagnostic accuracy and outcomes of intraoperative optical imaging methods. From these data, we derive recommendations for designing and reporting future studies.

Results

Available literature indicates that potential confounders and biases for reporting the diagnostic accuracy and usefulness of intraoperative optical imaging methods are seldom accounted for. Furthermore, methods for bias reduction are rarely used nor reported.

Conclusions

Detailed, transparent, and uniform reporting on diagnostic accuracy of intraoperative imaging methods is necessary. In the absence of such reporting, studies will not be comparable or reproducible. Future studies should consider some of the recommendations given here.

Electronic supplementary material

The online version of this article (10.1007/s00701-019-04007-y) contains supplementary material, which is available to authorized users.

Survival Outcomes Among Patients With High-Grade Glioma Treated With 5-Aminolevulinic Acid-Guided Surgery: A Systematic Review and Meta-Analysis

Background: High-grade glioma (HGG) is associated with a dismal prognosis despite significant advances in adjuvant therapies, including chemotherapy, immunotherapy, and radiotherapy. Extent of resection continues to be the most important independent prognosticator of survival. This underlines the significance of increasing gross total resection (GTR) rates by using adjunctive intraoperative modalities to maximize resection with minimal neurological morbidity. 5-aminolevulinic acid (5-ALA) is the only US Food and Drug Administration–approved intraoperative optical agent used for fluorescence-guided surgical resection of gliomas. Despite several studies on the impact of intra-operative 5-ALA use on the extent of HGG resection, a clear picture of how such usage affects patient survival is still unavailable.

Methods: A systematic review was conducted of all relevant studies assessing the GTR rate and survival outcomes [overall survival (OS) and progression-free survival (PFS)] in HGG. A meta-analysis of eligible studies was performed to assess the influence of 5-ALA-guided resection on improving GTR, OS, and PFS. GTR was defined as >95% resection.

Results: Of 23 eligible studies, 19 reporting GTR rates were included in the meta-analysis. The pooled cohort had 998 patients with HGG, including 796 with newly diagnosed cases. The pooled GTR rate among patients with 5-ALA–guided resection was 76.8% (95% confidence interval, 69.1–82.9%). A comparative subgroup analysis of 5-ALA–guided vs. conventional surgery (controlling for within-study covariates) showed a 26% higher GTR rate in the 5-ALA subgroup (odds ratio, 3.8; P < 0.001). There were 11 studies eligible for survival outcome analysis, 4 of which reported PFS. The pooled mean difference in OS and PFS was 3 and 1 months, respectively, favoring 5-ALA vs. control (P < 0.001).

Conclusions: This meta-analysis shows a significant increase in GTR rate with 5-ALA–guided surgical resection, with a higher weighted GTR rate (~76%) than the pivotal phase III study (~65%). Pooled analysis showed a small yet significant increase in survival measures associated with the use of 5-ALA. Despite the statistically significant results, the low level of evidence and heterogeneity across these studies make it difficult to conclusively report an independent association between 5-ALA use and survival outcomes in HGG. Additional randomized control studies are required to delineate the role of 5-ALA in survival outcomes in HGG.

Polymalic acid chlorotoxin nanoconjugate for near-infrared fluorescence guided resection of glioblastoma multiforme

Maximal surgical resection of glioma remains the single most effective treatment. Tools to guide the resection while avoiding removal of normal brain tissues can aid surgeons in achieving optimal results. One strategy to achieve this goal is to rely upon interoperative fluorescence staining of tumor cells in vivo, that can be visualized by the surgeon during resection. Towards this goal we have designed a biodegradable fluorescent mini nano imaging agent (NIA) with high specificity for U87MG glioma cells and previously unmet high light emission. The NIA is the conjugate of polymalic acid (PMLA) with chlorotoxin for tumor targeting, indocyanine green (ICG) for NIR fluorescence and the tri-leucin peptide as fluorescence enhancer. PMLA as a multivalent platform carries several molecules of ICG and the other ligands. The NIA recognizes multiple sites on glioma cell surface, demonstrated by the effects of single and combined competitors. Systemic IV injection into xenogeneic mouse model carrying human U87MG glioblastoma indicated vivid tumor cell binding and internalization of NIA resulting in intensive and long-lasting tumor fluorescence. The NIA is shown to greatly improve tumor removal supporting its utility in clinical applications.

5-ALA fluorescence-guided surgery in pediatric brain tumors-a systematic review

BACKGROUND

5-Aminolevulinic acid (5-ALA)-guided resection of gliomas in adults enables better differentiation between tumor and normal brain tissue, allowing a higher degree of resection, and improves patient outcomes. In recent years, several reports have emerged regarding the use of 5-ALA in other brain tumor entities, including pediatric brains tumors. Since gross total resection (GTR) of many brain tumors in children is crucial and the role of 5-ALA-guided resection of these tumors is not clear, we sought to perform a comprehensive literature review on this topic.

METHODS

A systematic literature review of EMBASE and MEDLINE/PubMed databases revealed 19 eligible publications encompassing 175 5-ALA-guided operations on pediatric brain tumors. To prevent bias, publications were revised independently by two authors.

RESULTS

We found that 5-ALA-guided resection enabled the surgeons to identify the tumor more easily and was considered helpful mainly in cases of glioblastoma (GBM, 21/27, 78%), anaplastic ependymoma WHO grade III (10/14, 71%), and anaplastic astrocytoma (4/6, 67%). In contrast, cases of pilocytic astrocytomas (PAs) and medulloblastomas 5-ALA-guided surgery did not show consistent fluorescent signals and 5-ALA was considered helpful only in 12% and 22% of cases, respectively. Accumulation of fluorescent porphyrins seems to depend on WHO tumor grading. One important finding is that when 5-ALA-guided resections were considered helpful, the degree of resection was higher than is cases where it was not helpful. The rate of adverse events related to 5-ALA was negligible, especially new postoperative sequelae.

CONCLUSION

5-ALA could play a role in resection of pediatric brain tumors. However, further prospective clinical trials are needed.

Maximizing safe resections: the roles of 5-aminolevulinic acid and intraoperative MR imaging in glioma surgery-review of the literature

Malignant glioma surgery involves the challenge of preserving the neurological status of patients harboring these lesions while pursuing a maximal tumor resection, which is correlated with overall and progression-free survival. Presently, several tools exist for assisting neurosurgeons in visualizing malignant tissue. Fluorescence-guided surgery (FGS) with 5-aminolevulinic acid (5-ALA) has increasingly been used during the last decade for identifying malignant glioma. Intraoperative magnetic resonance imaging (iMRI), first introduced in the mid-1990s, is being evaluated as a further tool to maximize the extent of resection. We aimed to evaluate the literature and discuss synergies and differences between FGS with 5-ALA and iMRI. We conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. After excluding non-relevant articles, 16 articles were evaluated and included in the qualitative analysis, comprising 2 (n = 2) reviews of the literatures, 1 (n = 1) book chapter, and 13 (n = 13) clinical articles. ALA-induced fluorescence goes beyond the borders of gadolinium contrast enhancement. Several studies stress the synergy between both tools, enabling increase in extent of resection. We point out advantages of combining both methods. iMRI, however, is not widely available, is expensive, and is not recommended as sole resection control tool in high-grade glioma. For these centers, FGS together with mapping and monitoring techniques, neuronavigation and, when needed, intraoperative ultrasound provides an excellent setting for achieving state-of-the-art gross total resection of high-grade gliomas.

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

BACKGROUND

When feasible, the surgical resection is the standard first step of the management of high-grade gliomas. 5-ALA fluorescence-guided-surgery (5-ALA-FGS) was developed to ease the intra-operative delineation of tumor borders in order to maximize the extent of resection.

METHODS

A Medline electronic database search was conducted. English language studies from January 1998 until July 2018 were included, following the PRISMA guidelines.

RESULTS

5-ALA can be considered as a specific tool for the detection of tumor remnant but has a weaker sensibility (level 2). 5-ALA-FGS is associated with a significant increase in the rate of gross total resection reaching more than 90% in some series (level 1). Consistently, 5-ALAFGS improves progression-free survival (level 1). However, the gain in overall survival is more debated. The use of 5-ALA-FGS in eloquent areas is feasible but requires simultaneous intraoperative electrophysiologic functional brain monitoring to precisely locate and preserve eloquent areas (level 2). 5-ALA is usable during the first resection of a glioma but also at recurrence (level 2). From a practical standpoint, 5-ALA is orally administered 3 hours before the induction of anesthesia, the recommended dose being 20 mg/kg. Intra-operatively, the procedure is performed as usually with a central debulking and a peripheral dissection during which the surgeon switches from white to blue light. Provided that some precautions are observed, the technique does not expose the patient to particular complications.

CONCLUSION

Although 5-ALA-FGS contributes to improve gliomas management, there are still some limitations. Future methods will be developed to improve the sensibility of 5-ALA-FGS.

Review of first clinical experiences with a 1.5 Tesla ceiling-mounted moveable intraoperative MRI system in Europe

High-field intraoperative MRI (iMRI) systems provide excellent imaging quality and are used for resection control and update of image guidance systems in a number of centers. A ceiling-mounted intraoperative MRI system has several advantages compared to a conventional iMRI system. In this article, we report on first clinical experience with using such a state-of-the-art, the 1.5T iMRI system, in Europe. A total of 50 consecutive patients with intracranial tumors and vascular lesions were operated in the iMRI unit. We analyzed the patients' data, surgery preparation times, intraoperative scans, surgical time, and radicality of tumor removal. Patients' mean age was 46 years (range 8 to 77 years) and the median surgical procedure time was 5 hours (range 1 to 11 hours). The lesions included 6 low-grade gliomas, 8 grade III astrocytomas, 10 glioblastomas, 7 metastases, 7 pituitary adenomas, 2 cavernomas, 2 lymphomas, 1 cortical dysplasia, 3 aneurysms, 1 arterio-venous malformation and 1 extracranial-intracranial bypass, 1 clival chordoma, and 1 Chiari malformation. In the surgical treatment of tumor lesions, intraoperative imaging depicted tumor remnant in 29.7% of the cases, which led to a change in the intraoperative strategy. The mobile 1.5T iMRI system proved to be safe and allowed an optimal workflow in the iMRI unit. Due to the fact that the MRI scanner is moved into the operating room only for imaging, the working environment is comparable to a regular operating room.

Simultaneous release of two drugs from polymer nano-implant inhibits recurrence in glioblastoma spheroids

Local implant-based delivery of rationally selected combination of chemotherapeutics has some major advantages for the treatment of glioblastoma such as: (a) 100 % bio-availability locally in brain can be achieved at the tumor site (b) avoid systemic leakage and associated toxicity, and (c) simultaneous inhibition of multiple, mutually exclusive cancer mechanisms is possible. Here, we report a polymeric brain implant capable of delivering two different drugs in recur-rent glioma cells. We have selected a combination of clinically used DNA alkylating agent, Te-mozolomide, and a DNA mismatch repair protein (Ligase IV) inhibitor, SCR-7, and delivered simultaneously into tumor spheroids formed by rat glioma cells, C6. The dual-drug loaded polymeric wafer, prepared by lyophilization method, could deliver both the drugs in a controlled fashion. To test the efficacy of this system, we have optimized an in vitro recurrent model of glioma spheroids wherein, the implant released both the drugs in a sustained fashion, thereby continuously exposing the cells to DNA methylation while inhibiting the DNA repair pathways. This leads to synergistic toxicity and inhibition of tumor recurrence for extended duration compared to free drug combination.

Surgical Adjuncts to Increase the Extent of Resection: Intraoperative MRI, Fluorescence, and Raman Histology

In low-grade glioma surgery, depicting tumor margins is challenging. 7 - Bowden 2018 - Sodium Fluorescein Facilitates Guided Sampling of Diagnostic Tumor Tissue.pdf Several tools have emerged to assist surgical decision-making. Intraoperative MRI, albeit expensive and time-consuming, can provide useful information during surgery. Fluorescence-guidance with 5-aminolevulinic acid (5-ALA) helps provide real-time information during surgery regardless of brain-shift, assists in finding anaplastic foci in low-grade tumors, and enables diagnosis of malignant tissue. Raman histology has potential for detecting viable tumor in biopsied tissue and for identifying tumor infiltration in vivo. This article analyzes and discusses these surgical adjuncts.

ω-3 and ω-6 Fatty Acids Modulate Conventional and Atypical Protein Kinase C Activities in a Brain Fatty Acid Binding Protein Dependent Manner in Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is a highly infiltrative brain cancer with a dismal prognosis. High levels of brain fatty acid binding protein (B-FABP) are associated with increased migration/infiltration in GBM cells, with a high ratio of arachidonic acid (AA) to docosahexaenoic acid (DHA) driving B-FABP-mediated migration. Since several protein kinase Cs (PKCs) are overexpressed in GBM and linked to migration, we explored a possible relationship between B-FABP and levels/activity of different PKCs, as a function of AA and DHA supplementation. We report that ectopic expression of B-FABP in U87 cells alters the levels of several PKCs, particularly PKCζ. Upon analysis of PKCζ RNA levels in a panel of GBM cell lines and patient-derived GBM neurospheres, we observed a trend towards moderate positive correlation (r = 0.624, p = 0.054) between B-FABP and PKCζ RNA levels. Analysis of PKC activity in U87 GBM cells revealed decreased typical PKC activity (23.4%) in B-FABP-expressing cells compared with nonexpressing cells, with no difference in novel and atypical PKC activities. AA and DHA modulated both conventional and atypical PKC activities in a B-FABP-dependent manner, but had no effect on novel PKC activity. These results suggest that conventional and atypical PKCs are potential downstream effectors of B-FABP/fatty acid-mediated alterations in GBM growth properties.

With a Little Help from My Friends: The Role of Intraoperative Fluorescent Dyes in the Surgical Management of High-Grade Gliomas

High-grade gliomas (HGGs) are the most frequent primary malignant brain tumors in adults, which lead to death within two years of diagnosis. Maximal safe resection of malignant gliomas as the first step of multimodal therapy is an accepted goal in malignant glioma surgery. Gross total resection has an important role in improving overall survival (OS) and progression-free survival (PFS), but identification of tumor borders is particularly difficult in HGGS. For this reason, imaging adjuncts, such as 5-aminolevulinic acid (5-ALA) or fluorescein sodium (FS) have been proposed as superior strategies for better defining the limits of surgical resection for HGG. 5-aminolevulinic acid (5-ALA) is implicated as precursor in the synthetic pathway of heme group. Protoporphyrin IX (PpIX) is an intermediate compound of heme metabolism, which produces fluorescence when excited by appropriate light wavelength. Malignant glioma cells have the capacity to selectively synthesize or accumulate 5-ALA-derived porphyrins after exogenous administration of 5-ALA. Fluorescein sodium (FS), on the other hand, is a fluorescent substance that is not specific to tumor cells but actually it is a marker for compromised blood-brain barrier (BBB) areas. Its effectiveness is confirmed by multicenter phase-II trial (FLUOGLIO) but lack of randomized phase III trial data. We conducted an analytic review of the literature with the objective of identifying the usefulness of 5-ALA and FS in HGG surgery in adult patients.

From imaging to biology of glioblastoma: new clinical oncology perspectives to the problem of local recurrence

GBM is one of the most common and aggressive brain tumors. Surgery and adjuvant chemoradiation have succeeded in providing a survival benefit. Although most patients will eventually experience local recurrence, the means to fight recurrence are limited and prognosis remains poor. In a disease where local control remains the major challenge, few trials have addressed the efficacy of local treatments, either surgery or radiation therapy. The present article reviews recent advances in the biology, imaging and biomarker science of GBM as well as the current treatment status of GBM, providing new perspectives to the problem of local recurrence.

Various shades of red-a systematic analysis of qualitative estimation of ALA-derived fluorescence in neurosurgery

5-Aminolevulinic acid (5-ALA)-fluorescence-guided resection is well established in many neuro-oncologic centers. Different classifications of 5-ALA-induced fluorescence have been reported. The aim of the systematic analysis was to evaluate the frequency of graduations, definitions, and designations of 5-ALA-induced fluorescence qualities. A systematic database search of PubMed was performed to identify studies reporting (1) on 5-ALA fluorescence-guided either spinal or cranial surgery, (2) on qualitative estimation and/or categorization of 5-ALA-induced fluorescence, (3) in English, and (4) were published as peer-reviewed original studies. Totally, 93 studies were identified. Different classification systems of 5-ALA-induced fluorescence were found. Over 60 % of the included studies used a dichotomized categorization of 5-ALA-induced fluorescence and 27.5 % of studies distinguished two different intensities of 5-ALA fluorescent tissue in addition to non-fluorescing tissue. More than 50 % of studies explicitly defined criteria for categorization of 5-ALA-induced fluorescence. The major limitation of the present analysis might be that it mainly comprises data from retrospective, uncontrolled, non-randomized trials. However, a precise definition of each 5-ALA-induced fluorescence quality is essential. Although dichotomized classification is the most common and simple graduation system, it may not be suitable for every clinical or scientific task. A three-level 5-ALA-induced fluorescence classification with precise definition of each fluorescence quality and their correlation with histological features would be more useful and reproducible in these cases.

Supra-complete surgery via dual intraoperative visualization approach (DiVA) prolongs patient survival in glioblastoma

Safe and complete resection represents the first step in the treatment of glioblastomas and is mandatory in increasing the effectiveness of adjuvant therapy to prolong overall survival. With gross total resection currently limited in extent to MRI contrast enhancing areas, the extent to which supra-complete resection beyond obvious contrast enhancement could have impact on overall survival remains unclear. DiVA (dual intraoperative visualization approach) redefines gross total resection as currently accepted by enabling for the first time supra-complete surgery without compromising patient safety. This approach exploits the advantages of two already accepted surgical techniques combining intraoperative MRI with integrated functional neuronavigation and 5-ALA by integrating them into a single surgical approach. We investigated whether this technique has impact on overall outcome in GBM patients. 105 patients with GBM were included. We achieved complete resection with intraoperative MRI alone according to current best-practice in glioma surgery in 75 patients. 30 patients received surgery with supra-complete resection. The control arm showed a median life expectancy of 14 months, reflecting current standards-of-care and outcome. In contrast, patients receiving supra-complete surgery displayed significant increase in median survival time to 18.5 months with overall survival time correlating directly with extent of supra-complete resection. This extension of overall survival did not come at the cost of neurological deterioration. We show for the first time that supra-complete glioma surgery leads to significant prolongation of overall survival time in GBM patients.

Fluorescence Imaging/Agents in Tumor Resection

Intraoperative fluorescence imaging allows real-time identification of diseased tissue during surgery without being influenced by brain shift and surgery interruption. 5-Aminolevulinic acid, useful for malignant gliomas and other tumors, is the most broadly explored compound approved for fluorescence-guided resection. Intravenous fluorescein sodium has recently received attention, highlighting tumor tissue based on extravasation at the blood-brain barrier (defective in many brain tumors). Fluorescein in perfused brain, unselective extravasation in brain perturbed by surgery, and propagation with edema are concerns. Fluorescein is not approved but targeted fluorochromes with affinity to brain tumor cells, in development, may offer future advantages.

Safety, Utility, and Clinical Results of Continuous Intraoperative Electrophysiologic Monitoring in 1.5T iMRI-Guided Surgery

OBJECTIVE

To show that the combined use of intraoperative high-field MRI (iMRI) and electrophysiologic monitoring (IOM) is feasible, safe, and beneficial for patients.

METHODS

The setup, surgical, imaging, and clinical results of 110 patients with eloquent intracranial lesions with the combined use of 1.5T iMRI and IOM were analyzed.

RESULTS

187 iMRI scans were performed with IOM needles in place, resulting in a total experience of using >4000 electrodes in the iMRI. No complication (ferromagnetic or relevant heating/burning of skin) was caused by the combined use of both technologies. Surgically induced severe postoperative sensorimotor deficits were seen in 11.8%. The surgeon's estimation of a "complete resection" proved to be true postoperatively in 90.3%. If the resection was stopped due to worsening of IOM, postoperative MRI revealed residual disease to be located in direct vicinity of eloquence in 27 of 28 cases, but not in other parts of the resection cavity. Of these patients, only 7% (2 of 28) had relevant new deficits after 3 months. In 82 patients (74.5%), the resection was continued after the iMRI scan, whereas in only 18 patients (16.4%) the resection was already completed at this point.

CONCLUSION

The combined use of IOM and 1.5T iMRI is feasible and safe. The complementary use of both technologies might result in more radical resections at comparable surgically induced neurologic deficits. If available and indicated, the combined use of IOM and iMRI should be performed on a routine basis.

Intraoperative MRI for the management of brain lesions adjacent to eloquent areas

BACKGROUND

The aim of our study was to report the usefulness of intraoperative MRI guidance in the resection of brain lesions adjacent to eloquent areas.

PATIENTS AND METHODS

A single center prospective series of gliomas amenable to optimized resection with intraoperative MRI between September 2014 and December 2015.

RESULTS

The study included 56 patients. The median duration of the first intraoperative MRI was 38min, interquartile range (IQR 30-46). Fourteen patients (40%) underwent a second intraoperative MRI, which had a median duration of 26min (IQR, 18-30). The median total operative time was 265min (IQR, 242-337). After the first intraoperative MRI, the median residual glioma volume of the 35 gliomas adjacent to eloquent areas was 7.04cm³ (IQR, 2.22-13.8), which did not significantly differ from the other gliomas (P=0.07). After the second intraoperative MRI, the median residual glioma volume was 3.86cm³ (IQR, 0.82-6.99), which did not significantly differ from the other patients (P=0.700). On the postoperative MRI, the median extent of the glioma resections adjacent to eloquent areas was 99.78% (IQR, 88.9-100), which was not significantly different from the rest of the population (P=0.290). At 6 months after surgery, the median Karnofsky Performance Score was 90, and 2.8% of the patients presented a permanent new neurological deficit.

CONCLUSION

Our results suggest that intraoperative MRI is an effective and safe technique to improve the extent of brain lesion resections close to eloquent areas.

Agents for fluorescence-guided glioma surgery: a systematic review of preclinical and clinical results

BACKGROUND

Fluorescence-guided surgery (FGS) is a technique used to enhance visualization of tumor margins in order to increase the extent of tumor resection in glioma surgery. In this paper, we systematically review all clinically tested fluorescent agents for application in FGS for glioma and all preclinically tested agents with the potential for FGS for glioma.

METHODS

We searched the PubMed and Embase databases for all potentially relevant studies through March 2016. We assessed fluorescent agents by the following outcomes: rate of gross total resection (GTR), overall and progression-free survival, sensitivity and specificity in discriminating tumor and healthy brain tissue, tumor-to-normal ratio of fluorescent signal, and incidence of adverse events.

RESULTS

The search strategy resulted in 2155 articles that were screened by titles and abstracts. After full-text screening, 105 articles fulfilled the inclusion criteria evaluating the following fluorescent agents: 5-aminolevulinic acid (5-ALA) (44 studies, including three randomized control trials), fluorescein (11), indocyanine green (five), hypericin (two), 5-aminofluorescein-human serum albumin (one), endogenous fluorophores (nine) and fluorescent agents in a pre-clinical testing phase (30). Three meta-analyses were also identified.

CONCLUSIONS

5-ALA is the only fluorescent agent that has been tested in a randomized controlled trial and results in an improvement of GTR and progression-free survival in high-grade gliomas. Observational cohort studies and case series suggest similar outcomes for FGS using fluorescein. Molecular targeting agents (e.g., fluorophore/nanoparticle labeled with anti-EGFR antibodies) are still in the pre-clinical phase, but offer promising results and may be valuable future alternatives.

Epigenetics in Brain Tumors: HDACs Take Center Stage

Primary tumors of the brain account for 2 % of all cancers with malignant gliomas taking the lion’s share at 70 %. Malignant gliomas (high grade gliomas WHO° III and °IV) belong to one of the most threatening tumor entities known for their disappointingly short median survival time of just 14 months despite maximum therapy according to current gold standards. Malignant gliomas manifest various factors, through which they adapt and manipulate the tumor microenvironment to their advantage. Epigenetic mechanisms operate on the tumor microenvironment by de- and methylation processes and imbalances between the histone deacetylases (HDAC) and histone acetylases (HAT). Many compounds have been discovered modulating epigenetically controlled signals. Recent studies indicate that xCT (system xc-, SLC7a11) and CD44 (H-CAM, ECM-III, HUTCH-1) functions as a bridge between these epigenetic regulatory mechanisms and malignant glioma progression. The question that ensues is the extent to which therapeutic intervention on these signaling pathways would exert influence on the treatment of malignant gliomas as well as the extent to which manipulation of HDAC activity can sensitize tumor cells for chemotherapeutics through ‘epigenetic priming’. In light of considering the current stagnation in the development of therapeutic options, the need for new strategies in the treatment of gliomas has never been so pressing. In this context the possibility of pharmacological intervention on tumor-associated genes by epigenetic priming opens a novel path in the treatment of primary brain tumors.

Clinical utility of 5-aminolevulinic acid HCl to better visualize and more completely remove gliomas

Surgical resection is typically the first line of treatment for gliomas. However, the neurosurgeon faces a major challenge in achieving maximal resection in high-grade gliomas as these infiltrative tumors make it difficult to discern tumor margins from normal brain with conventional white-light microscopy alone. To aid in resection of these infiltrative tumors, fluorescence-guided surgery has gained much popularity in intraoperative visualization of malignant gliomas, with 5-aminolevulinic acid (5-ALA) leading the way. First introduced in an article in Neurosurgery, 5-ALA has since become a safe, effective, and inexpensive method to visualize and improve resection of gliomas. This has undoubtedly led to improvements in the clinical course of patients as demonstrated by the increased overall and progression-free survival in patients with such devastating disease. This literature review aims to discuss the major studies and trials demonstrating the clinical utility of 5-ALA and its ability to aid in complete resection of malignant gliomas.

Quantitative evaluation of malignant gliomas damage induced by photoactivation of IR700 dye

The processes involved in malignant gliomas damage were quantitatively evaluated by microscopy. The near-infrared fluorescent dye IR700 that is conjugated to an anti-CD133 antibody (IR700-CD133) specifically targets malignant gliomas (U87MG) and stem cells (BT142) and is endocytosed into the cells. The gliomas are then photodamaged by the release of reactive oxygen species (ROS) and the heat induced by illumination of IR700 by a red laser, and the motility of the vesicles within these cells is altered as a result of cellular damage. To investigate these changes in motility, we developed a new method that measures fluctuations in the intensity of phase-contrast images obtained from small areas within cells. The intensity fluctuation in U87MG cells gradually decreased as cell damage progressed, whereas the fluctuation in BT142 cells increased. The endocytosed IR700 dye was co-localized in acidic organelles such as endosomes and lysosomes. The pH in U87MG cells, as monitored by a pH indicator, was decreased and then gradually increased by the illumination of IR700, while the pH in BT142 cells increased monotonically. In these experiments, the processes of cell damage were quantitatively evaluated according to the motility of vesicles and changes in pH.

The effectiveness and cost-effectiveness of intraoperative imaging in high-grade glioma resection; a comparative review of intraoperative ALA, fluorescein, ultrasound and MRI

BACKGROUND

Surgical resection of high-grade gliomas (HGG) is standard therapy because it imparts significant progression free (PFS) and overall survival (OS). However, HGG-tumor margins are indistinguishable from normal brain during surgery. Hence intraoperative technology such as fluorescence (ALA, fluorescein) and intraoperative ultrasound (IoUS) and MRI (IoMRI) has been deployed. This study compares the effectiveness and cost-effectiveness of these technologies.

METHODS

Critical literature review and meta-analyses, using MEDLINE/PubMed service. The list of references in each article was double-checked for any missing references. We included all studies that reported the use of ALA, fluorescein (FLCN), IoUS or IoMRI to guide HGG-surgery. The meta-analyses were conducted according to statistical heterogeneity between studies. If there was no heterogeneity, fixed effects model was used; otherwise, a random effects model was used. Statistical heterogeneity was explored by χ² and inconsistency (I²) statistics. To assess cost-effectiveness, we calculated the incremental cost per quality-adjusted life-year (QALY).

RESULTS

Gross total resection (GTR) after ALA, FLCN, IoUS and IoMRI was 69.1%, 84.4%, 73.4% and 70% respectively. The differences were not statistically significant. All four techniques led to significant prolongation of PFS and tended to prolong OS. However none of these technologies led to significant prolongation of OS compared to controls. The cost/QALY was $16,218, $3181, $6049 and $32,954 for ALA, FLCN, IoUS and IoMRI respectively.

CONCLUSIONS

ALA, FLCN, IoUS and IoMRI significantly improve GTR and PFS of HGG. Their incremental cost was below the threshold for cost-effectiveness of HGG-therapy, denoting that each intraoperative technology was cost-effective on its own.

Probing the Druggability Limits for Enzymes of the NAD Biosynthetic Network in Glioma

The biosynthesis of NAD constitutes an important metabolic module in the cell, since NAD is an essential cofactor involved in several metabolic reactions. NAD concentrations are known to be significantly increased in several cancers, particularly in glioma, consistent with the observation of up-regulation of several enzymes of the network. Modulating NAD biosynthesis in glioma is therefore an attractive therapeutic strategy. Here we report reconstruction of a biochemical network of NAD biosynthesis consisting of 22 proteins, 36 metabolites, and 86 parameters, tuned to mimic the conditions in glioma. Kinetic simulations of the network provide comprehensive insights about the role of individual enzymes. Further, quantitative changes in the same network between different states of health and disease enable identification of drug targets, based on specific alterations in the given disease. Through simulations of enzyme inhibition titrations, we identify NMPRTase as a potential drug target, while eliminating other possible candidates NMNAT, NAPRTase, and NRK. We have also simulated titrations of both binding affinities as well as inhibitor concentrations, which provide insights into the druggability limits of the target, a novel aspect that can provide useful guidelines for designing inhibitors with optimal affinities. Our simulations suggest that an inhibitor affinity of 10 nM used in a concentration range of 0.1 to 10 μM achieves a near maximal inhibition response for NMPRTase and that increasing the affinity any further is not likely to have a significant advantage. Thus, the quantitative appreciation defines a maximal extent of inhibition possible for a chosen enzyme in the context of its network. Knowledge of this type enables an upper affinity threshold to be defined as a goal in lead screening and refinement stages in drug discovery.

The value of using a brain laser interstitial thermal therapy (LITT) system in patients presenting with high grade gliomas where maximal safe resection may not be feasible

Background

The objective of this analysis was to determine the value (incremental cost/increment benefit) of a brain LITT system versus employing current surgical options recommended by NCCN guidelines, specifically open resection (i.e. craniotomy) methods or biopsy (collectively termed CURRENT TREATMENTS) in patients where maximal safe resection may not be feasible. As has been demonstrated in the literature, extent of resection/ablation with minimal complications are independently related to overall survival.

Methods

A cost effectiveness analysis from a societal perspective was employed using TreeAge Pro 2014 software. Direct costs (using national average Medicare reimbursement amounts), outcomes (overall survival), and value [defined as increment cost/incremental survival—evaluated as cost/life year gained (LYG)] were evaluated. Sensitivity analysis was also performed to determine which variables had the largest effect on incremental costs and outcomes.

Results

In the base case, the overall survival was improved with brain LITT versus CURRENT TREATMENTS by 3.07 months at an additional cost of $7508 (or $29,340/LYG). This amount was significantly less than the current international threshold value for $32,575/LYG and considerably less than the US threshold value of $50,000/LYG. This incremental cost may also qualify under NICE criteria for end of life therapies. In sensitivity analysis: As percent local recurrence GBM increased; cost of DRG25/26 increased; percent GTR increased; and gliadel use increased—the value of brain LITT improved. Additionally, in those patients where a biopsy is the only option, brain LITT extended life by 7 months.

Conclusions

Brain LITT should be considered a viable option for treatment of high grade gliomas as it improves survival at a cost which appears to be of good value to society. This incremental cost is less than the international and US thresholds for good value.