Gamma knife surgery for glioblastoma multiforme

Revolutionizing Glioblastoma Treatment: A Comprehensive Overview of Modern Therapeutic Approaches

Glioblastoma is the most common malignant primary brain tumor in the adult population, with an average survival of 12.1 to 14.6 months. The standard treatment, combining surgery, radiotherapy, and chemotherapy, is not as efficient as we would like. However, the current possibilities are no longer limited to the standard therapies due to rapid advancements in biotechnology. New methods enable a more precise approach by targeting individual cells and antigens to overcome cancer. For the treatment of glioblastoma, these are gamma knife therapy, proton beam therapy, tumor-treating fields, EGFR and VEGF inhibitors, multiple RTKs inhibitors, and PI3K pathway inhibitors. In addition, the increasing understanding of the role of the immune system in tumorigenesis and the ability to identify tumor-specific antigens helped to develop immunotherapies targeting GBM and immune cells, including CAR-T, CAR-NK cells, dendritic cells, and immune checkpoint inhibitors. Each of the described methods has its advantages and disadvantages and faces problems, such as the inefficient crossing of the blood-brain barrier, various neurological and systemic side effects, and the escape mechanism of the tumor. This work aims to present the current modern treatments of glioblastoma.

Efficacy and indications of gamma knife radiosurgery for recurrent low-and high-grade glioma

PURPOSE

To investigate the indications and efficacy of gamma knife radiosurgery (GKRS) as a salvage treatment for recurrent low-and high-grade glioma.

METHODS

This retrospective study of 107 patients with recurrent glioma treated with GKRS between 2009 and 2022, including 68 high-grade glioma (HGG) and 39 low-grade glioma (LGG) cases. The Kaplan-Meier method was used to calculate the overall survival (OS) and progression-free survival (PFS). The log-rank test was used to analyze the multivariate prognosis of the Cox proportional hazards model. Adverse reactions were evaluated according to the Common Terminology Criteria for Adverse Events version 4.03. The prognostic value of main clinical features was estimated, including histopathology, Karnofsky performance status (KPS), recurrence time interval, target location, two or more GKRS, surgery for recurrence, site of recurrence, left or right side of the brain and so on.

RESULTS

The median follow-up time was 74.5 months. The median OS and PFS were 17.0 months and 5.5 months for all patients. The median OS and PFS were 11.0 months and 5.0 months for HGG, respectively. The median OS and PFS were 49.0 months and 12.0 months for LGG, respectively. Multivariate analysis showed that two or more GKRS, left or right side of the brain and brainstem significantly affected PFS. Meanwhile, the KPS index, two or more GKRS, pathological grade, and brainstem significantly affected OS. Stratified analysis showed that surgery for recurrence significantly affected OS and PFS for LGG. KPS significantly affected OS and PFS for HGG. No serious adverse events were noted post-GKRS.

CONCLUSION

GKRS is a safe and effective salvage treatment for recurrent glioma. Moreover, it can be applied after multiple recurrences with tolerable adverse effects.

Bevacizumab and gamma knife radiosurgery for first-recurrence glioblastoma

INTRODUCTION

Glioblastoma (GBM) is the most common central nervous system malignancy in adults. Despite decades of developments in surgical management, radiation treatment, chemotherapy, and tumor treating field therapy, GBM remains an ultimately fatal disease. There is currently no definitive standard of care for patients with recurrent glioblastoma (rGBM) following failure of initial management.

OBJECTIVE

In this retrospective cohort study, we set out to examine the relative effects of bevacizumab and Gamma Knife radiosurgery on progression-free survival (PFS) and overall survival (OS) in patients with GBM at first-recurrence.

METHODS

We conducted a retrospective review of all patients with rGBM who underwent treatment with bevacizumab and/or Gamma Knife radiosurgery at Roswell Park Comprehensive Cancer Center between 2012 and 2022. Mean PFS and OS were determined for each of our three treatment groups: Bevacizumab Only, Bevacizumab Plus Gamma Knife, and Gamma Knife Only.

RESULTS

Patients in the combined treatment group demonstrated longer post-recurrence median PFS (7.7 months) and median OS (11.5 months) compared to glioblastoma patients previously reported in the literature, and showed improvements in total PFS (p=0.015), total OS (p=0.0050), post-recurrence PFS (p=0.018), and post-recurrence OS (p=0.0082) compared to patients who received either bevacizumab or Gamma Knife as monotherapy.

CONCLUSION

This study demonstrates that the combined use of bevacizumab with concurrent stereotactic radiosurgery can have improve survival in patients with rGBM.

Preclinical models of glioblastoma: limitations of current models and the promise of new developments

Glioblastoma (GBM) is the most common and aggressive primary brain tumour, yet little progress has been made towards providing better treatment options for patients diagnosed with this devastating condition over the last few decades. The complex nature of the disease, heterogeneity, highly invasive potential of GBM tumours and until recently, reduced investment in research funding compared with other cancer types, are contributing factors to few advancements in disease management. Survival rates remain low with less than 5% of patients surviving 5 years. Another important contributing factor is the use of preclinical models that fail to fully recapitulate GBM pathophysiology, preventing efficient translation from the lab into successful therapies in the clinic. This review critically evaluates current preclinical GBM models, highlighting advantages and disadvantages of using such models, and outlines several emerging techniques in GBM modelling using animal-free approaches. These novel approaches to a highly complex disease such as GBM show evidence of a more truthful recapitulation of GBM pathobiology with high reproducibility. The resulting advancements in this field will offer new biological insights into GBM and its aetiology with potential to contribute towards the development of much needed improved treatments for GBM in future.

Development of novel ruthenium(II)-arene complexes displaying potent anticancer effects in glioblastoma cells

Glioblastomas (GBs) are highly aggressive and malignant brain tumors, which are highly resistant to conventional multimodal treatments, leading to their abysmal prognosis. Herein, we designed two organometallic half-sandwich Ru(ii)-η6-p-cymene complexes containing Schiff bases derived from 3-aminoquinoline and 2-hydroxy-benzaldehyde (L1) and 2-hydroxy-naphthaldehyde (L2), namely [Ru(η6-p-cymene)(L1)Cl] (1) and [Ru(η6-p-cymene)(L2)Cl] (2), respectively, and studied their activity on GB cells. Both complexes were structurally characterized using single-crystal X-ray diffraction, which exhibited their half-sandwich three-legged piano-stool geometry. Furthermore, we studied their physicochemical behavior, solution speciation, aquation kinetics, and photo-substitution reactions using various spectroscopic methods. The complexes exhibited a moderate binding affinity with calf-thymus (CT)-DNA (Kb ∼ 105 M-1). The complexes effectively interacted with human serum albumin (HSA) (K ∼ 105 M-1) with preferential tryptophan binding, as determined via synchronous fluorescence studies. The in vitro studies showed their significant antiproliferative activity against an aggressive human GB cell line, LN-229 (IC50 = 22.8 μM), with moderate selectivity relative to normal mouse fibroblast L929 cells. Notably, [Ru(η6-p-cymene)(L1)Cl] (1) exhibited a higher selectivity index (S.I.) than [Ru(η6-p-cymene)(L2)Cl] (2) and cisplatin. We evaluated the clonogenic potential of the GB cells using a colony formation assay in the presence of complex 1. Excitingly, it showed ∼75% inhibition of the clonogenic potential of GB cells at the IC50 concentration. Complex 1 also effectively lowered the migratory potential of the GB cells, as assessed by the wound healing assay. The studied compound led to the apoptosis of GB cells, as evidenced by nuclear condensation, blebbing, and enhanced caspase 3/7 activity, and thus has anticipated utility in the treatment of GBs using photochemotherapy.

Role of gamma knife radiosurgery in the management of intracranial gliomas

Gamma knife for gliomas is a relatively obscure treatment modality with few reports and small series available on the same. An extensive search of English Language literature yields no comprehensive reviews of the same. We here, attempt to review the available literature on gamma knife for all types of gliomas: Low grade, High grade, recurrent, and also for pediatric populations. We used keywords such as "Gamma Knife Glioma," "Stereotactic Radiosurgery Glioma," "Gamma Knife," "Adjuvant therapy Glioma" "Recurrent Glioma" on PubMed search engine, and articles were selected with respect to their use of gamma Knife for Gliomas and outcome for the same. These were then analyzed and salient findings were elucidated. This was combined with National Comprehensive Cancer Network guidelines for the same and also included our own initial experience with these tumors. Gamma-knife improved long term survival and quality of life in patients with low grade gliomas. In pediatric low grade gliomas, it may be considered as a treatment modality with a marginal dose of 12-14 Gy, especially in eloquent structures such as brain stem glioma, anterior optic pathway hypothalamic glioma. However, in newly diagnosed high-grade glioma gamma knife radiosurgery (GKRS) is not recommended because of a lack of definitive evidence in tumor control and quality of life. GKRS may find its role in palliative care of recurrent gliomas irrespective of type and grade. Inspite of growing experience with GKRS for gliomas, there is no Level I evidence in support of GKRS, hence better designed randomized controlled trials with long term outcomes are warranted. Although this modality is not a "one size fits all' therapy, it has its moments when chosen correctly and applied wisely. Gliomas being the most common tumors operated in any neurosurgical setting, knowledge about this modality and its application is essential and useful.

Extracellular Vesicle-Derived miR-124 Resolves Radiation-Induced Brain Injury

Radiation-induced cognitive dysfunction (RICD) is a progressive and debilitating health issue facing patients following cranial radiotherapy to control central nervous system cancers. There has been some success treating RICD in rodents using human neural stem cell (hNSC) transplantation, but the procedure is invasive, requires immunosuppression, and could cause other complications such as teratoma formation. Extracellular vesicles (EV) are nanoscale membrane-bound structures that contain biological contents including mRNA, miRNA, proteins, and lipids that can be readily isolated from conditioned culture media. It has been previously shown that hNSC-derived EV resolves RICD following cranial irradiation using an immunocompromised rodent model. Here, we use immunocompetent wild-type mice to show that hNSC-derived EV treatment administered either intravenously via retro-orbital vein injection or via intracranial transplantation can ameliorate cognitive deficits following 9 Gy head-only irradiation. Cognitive function assessed on the novel place recognition, novel object recognition, and temporal order tasks was not only improved at early (5 weeks) but also at delayed (6 months) postirradiation times with just a single EV treatment. Improved behavioral outcomes were also associated with reduced neuroinflammation as measured by a reduction in activated microglia. To identify the mechanism of action, analysis of EV cargo implicated miRNA (miR-124) as a potential candidate in the mitigation of RICD. Furthermore, viral vector-mediated overexpression of miR-124 in the irradiated brain ameliorated RICD and reduced microglial activation. Our findings demonstrate for the first time that systemic administration of hNSC-derived EV abrogates RICD and neuroinflammation in cranially irradiated wild-type rodents through a mechanism involving miR-124. SIGNIFICANCE: Radiation-induced neurocognitive decrements in immunocompetent mice can be resolved by systemic delivery of hNSC-derived EVs involving a mechanism dependent on expression of miR-124.

Patterns of Failure After Stereotactic Radiosurgery for Recurrent High-Grade Glioma: A Single Institution Experience of 10 Years

BACKGROUND

Stereotactic radiosurgery (SRS) is a treatment modality that is frequently used as salvage therapy for small nodular recurrent high-grade gliomas (HGG). Due to the infiltrative nature of HGG, it is unclear if this highly focused technique provides a durable local control benefit.

OBJECTIVE

To determine how demographic or clinical factors influence the pattern of failure following SRS for recurrent high-grade gliomas.

METHODS

We retrospectively reviewed clinical, radiographic, and follow-up information for 47 consecutive patients receiving SRS for recurrent HGG at our institution between June 2006 and July 2016. All patients initially presented with an HGG (WHO grade III and IV). Following SRS for recurrence, all patients experienced treatment failure, and we evaluated patterns of local, regional, and distant failure in relation to the SRS 50% isodose line.

RESULTS

Most patients with recurrent HGG developed "in-field" treatment failure following SRS (n = 40; 85%). Higher SRS doses were associated with longer time to failure (hazards ratio = 0.80 per 1 Gy increase; 95% confidence interval 0.67-0.96; P = .016). There was a statistically significant increase in distant versus in-field failure among older patients (P = .035). This effect was independent of bevacizumab use (odds ratio = 0.54, P = 1.0).

CONCLUSION

Based on our experience, the majority of treatment failures after SRS for recurrent HGG were "in-field." Older patients, however, presented with more distant failures. Our results indicate that higher SRS doses delivered to a larger area as fractioned or unfractioned regimen may prolong time to failure, especially in the older population.

Liposomal Lapatinib in Combination with Low-Dose Photodynamic Therapy for the Treatment of Glioma

BACKGROUND

Malignant gliomas are highly invasive and extremely difficult to treat tumours with poor prognosis and outcomes. Photodynamic therapy (PDT), mediated by Gleolan®, has been studied previously with partial success in treating these tumours and extending lifetime. We aim to determine whether combining PDT using ALA-protoporphyrin IX (PpIX) with a liposomal formulation of the clinical epidermal growth factor receptor (EGFR) inhibitor, lapatinib, would increase the anti-tumour PDT efficacy.

METHODS

Lapatinib was given in vitro and in vivo 24 h prior to PDT and for 3-5 days following PDT to elicit whether the combination provided any benefits to PDT therapy. Live-cell imaging, in vitro PDT, and in vivo studies were performed to elucidate the effect lapatinib had on PDT for a variety of glioma cell lines and as well as GSC-30 neurospheres in vivo.

RESULTS

PDT combined with lapatinib led to a significant increase in PpIX accumulation, and reductions in the LD₅₀ of PpIX mediated PDT in two EGFR-driven cell lines, U87 and U87vIII, tested (p < 0.05). PDT + lapatinib elicited stronger MRI-quantified glioma responses following PDT for two human glioma-derived tumours (U87 and GSC-30) in vivo (p < 0.05). Furthermore, PDT leads to enhanced survival in rats following treatment with lapatinib compared to lapatinib alone and PDT alone (p < 0.05).

CONCLUSIONS

As lapatinib is approved for other oncological indications, a realization of its potential combination with PDT and in fluorescence-guided resection could be readily tested clinically. Furthermore, as its use would only be in acute settings, long-term resistance should not pose an issue as compared to its use as monotherapy.

Indications and Efficacy of Gamma Knife Stereotactic Radiosurgery for Recurrent Glioblastoma: 2 Decades of Institutional Experience

BACKGROUND

The role of stereotactic radiosurgery (SRS) for recurrent glioblastoma and the radionecrosis risk in this setting remain unclear.

OBJECTIVE

To perform a large retrospective study to help inform proper indications, efficacy, and anticipated complications of SRS for recurrent glioblastoma.

METHODS

We retrospectively analyzed patients who underwent Gamma Knife SRS between 1991 and 2013. We used the partitioning deletion/substitution/addition algorithm to identify potential predictor covariate cut points and Kaplan-Meier and proportional hazards modeling to identify factors associated with post-SRS and postdiagnosis survival.

RESULTS

One hundred seventy-four glioblastoma patients (median age, 54.1 years) underwent SRS a median of 8.7 months after initial diagnosis. Seventy-five percent had 1 treatment target (range, 1-6), and median target volume and prescriptions were 7.0 cm 3 (range, 0.3-39.0 cm 3 ) and 16.0 Gy (range, 10-22 Gy), respectively. Median overall survival was 10.6 months after SRS and 19.1 months after diagnosis. Kaplan-Meier and multivariable modeling revealed that younger age at SRS, higher prescription dose, and longer interval between original surgery and SRS are significantly associated with improved post-SRS survival. Forty-six patients (26%) underwent salvage craniotomy after SRS, with 63% showing radionecrosis or mixed tumor/necrosis vs 35% showing purely recurrent tumor. The necrosis/mixed group had lower mean isodose prescription compared with the tumor group (16.2 vs 17.8 Gy; P = .003) and larger mean treatment volume (10.0 vs 5.4 cm 3 ; P = .009).

CONCLUSION

Gamma Knife may benefit a subset of focally recurrent patients, particularly those who are younger with smaller recurrences. Higher prescriptions are associated with improved post-SRS survival and do not seem to have greater risk of symptomatic treatment effect.

ALA-PpIX mediated photodynamic therapy of malignant gliomas augmented by hypothermia

Background

Malignant gliomas are highly invasive, difficult to treat, and account for 2% of cancer deaths worldwide. Glioblastoma Multiforme (GBM) comprises the most common and aggressive intracranial tumor. The study hypothesis is to investigate the modification of Photodynamic Therapy (PDT) efficacy by mild hypothermia leads to increased glioma cell kill while protecting normal neuronal structures.

Methods

Photosensitizer accumulation and PDT efficacy in vitro were quantified in various glioma cell lines, primary rat neurons, and astrocytes. In vivo studies were carried out in healthy brain and RG2 glioma of naïve Fischer rats. Hypothermia was induced at 1 hour pre- to 2 hours post-PDT, with ALA-PpIX accumulation and PDT treatments effects on tumor and normal brain PDT quantified using optical spectroscopy, histology, immunohistochemistry, MRI, and survival studies, respectively.

Findings

In vitro studies demonstrated significantly improved post-PDT survival in primary rat neuronal cells. Rat in vivo studies confirmed a neuroprotective effect to hypothermia following PpIX mediated PDT by T₂ mapping at day 10, reflecting edema/inflammation volume reduction. Mild hypothermia increased PpIX fluorescence in tumors five-fold, and the median post-PDT rat survival time (8.5 days normothermia; 14 days hypothermia). Histology and immunohistochemistry show close to complete cellular protection in normal brain structures under hypothermia.

Conclusions

The benefits of hypothermia on both normal neuronal tissue as well as increased PpIX fluorescence and RG2 induced rat survival strongly suggest a role for hypothermia in photonics-based surgical techniques, and that a hypothermic intervention could lead to considerable patient outcome improvements.

Combination Therapy with Low Copper Diet, Penicillamine and Gamma Knife Radiosurgery Reduces VEGF and IL-8 In Patients with Recurrent Glioblastoma

Purpose:

Vascular Endothelial Growth Factor (VEGF) and interleukin-8 (IL-8) appear important in tumor growth. In this study, we have investigated the effect of copper reduction along with gamma knife radiosurgery on IL-8 and VEGF in patients with recurrent glioblastoma multiforme (GBM).

Materials and Methods:

In a 3-month randomized clinical trial, patients with recurrent GBM were allocated randomly between intervention and placebo groups. Radiosurgery was performed for both groups (Reference dose: 16-18 Gray, in one fraction). The intervention group received low copper diet and penicillamine while the patients in the placebo group continued with their usual diet. VEGF and IL-8 were measured at baseline and the end of intervention.

Results:

VEGF in intervention group significantly reduced compared to placebo group (Mean ± SD, 4.5±1.91 vs. 7.8±3.21; P<0.001). IL-8 in intervention group decreased compared to placebo group but not significant (2.7±1.91 vs. 3.2±3.20; P=0.49). We also detected a significant positive correlation between serum copper and VEGF (r=0.57; P<0.05) and a negative correlation between KPS and serum copper.

Discussion:

Our results could reflect that low copper diet and penicillamine may decrease serum VEGF in patients who underwent gamma knife radiosurgery for recurrent glioblastoma multiforme.

Factors predictive of improved overall survival following stereotactic radiosurgery for recurrent glioblastoma

The currently accepted standard of care for primary glioblastoma (GBM) consists of maximal surgical resection followed by fractionated external beam radiotherapy (EBRT) with concomitant temozolomide chemotherapy. The role of stereotactic radiosurgery (SRS) in the treatment of GBM is not well defined, but SRS has typically been applied as a salvage therapy for GBM recurrence. This paper reviews our single institution experience using gamma knife radiosurgery (GKRS) for the treatment of GBM. Thirty-six patients treated with GKRS for pathologically proven GBM at LSU Health in Shreveport from February 2000 to December 2013 were identified and analyzed. Patient characteristics, treatment variables, and survival were correlated. Seven patients received GKRS in the immediate postoperative period for an average tumor volume of 10.9 cm(3), and 29 patients were treated for a recurrent average tumor volume of 11.4 cm(3) with a prescribed dose ranging from 10 to 20 Gy at the 50 % isodose line. The median overall survival was significantly higher in recurrence group compared to up-front group [7.9 months (0.77-32.1 months) vs. 3.5 months (range 0.23-11.7 months) respectively, (p = 0.018)]. The predictive factors for improved survival in the patients with GBM were as follows: Karnofsky performance scale (KPS) > 70 (p = 0.026), age ≤ 50 years (p = 0.006), absence of neurodeficits (p = 0.01), and initial postoperative treatment with EBRT (p = 0.042). Adjuvant therapy with GKRS following GBM recurrence demonstrates statistical superiority over immediate postoperative boost therapy.

miR-182 integrates apoptosis, growth, and differentiation programs in glioblastoma

Glioblastoma multiforme (GBM) is a lethal, therapy-resistant brain cancer consisting of numerous tumor cell subpopulations, including stem-like glioma-initiating cells (GICs), which contribute to tumor recurrence following initial response to therapy. Here, we identified miR-182 as a regulator of apoptosis, growth, and differentiation programs whose expression level is correlated with GBM patient survival. Repression of Bcl2-like12 (Bcl2L12), c-Met, and hypoxia-inducible factor 2α (HIF2A) is of central importance to miR-182 anti-tumor activity, as it results in enhanced therapy susceptibility, decreased GIC sphere size, expansion, and stemness in vitro. To evaluate the tumor-suppressive function of miR-182 in vivo, we synthesized miR-182-based spherical nucleic acids (182-SNAs); i.e., gold nanoparticles covalently functionalized with mature miR-182 duplexes. Intravenously administered 182-SNAs penetrated the blood-brain/blood-tumor barriers (BBB/BTB) in orthotopic GBM xenografts and selectively disseminated throughout extravascular glioma parenchyma, causing reduced tumor burden and increased animal survival. Our results indicate that harnessing the anti-tumor activities of miR-182 via safe and robust delivery of 182-SNAs represents a novel strategy for therapeutic intervention in GBM.

Magnetic resonance imaging-guided focused laser interstitial thermal therapy for intracranial lesions: single-institution series

BACKGROUND:

Surgical treatments for deep-seated intracranial lesions have been limited by morbidities associated with resection. Real-time magnetic resonance imaging–guided focused laser interstitial thermal therapy (LITT) offers a minimally invasive surgical treatment option for such lesions.

OBJECTIVE:

To review treatments and results of patients treated with LITT for intracranial lesions at Washington University School of Medicine.

METHODS:

In a review of 17 prospectively recruited LITT patients (34-78 years of age; mean, 59 years), we report demographics, treatment details, postoperative imaging characteristics, and peri- and postoperative clinical courses.

RESULTS:

Targets included 11 gliomas, 5 brain metastases, and 1 epilepsy focus. Lesions were lobar (n = 8), thalamic/basal ganglia (n = 5), insular (n = 3), and corpus callosum (n = 1). Mean target volume was 11.6 cm³, and LITT produced 93% target ablation. Patients with superficial lesions had shorter intensive care unit stays. Ten patients experienced no perioperative morbidities. Morbidities included transient aphasia, hemiparesis, hyponatremia, deep venous thrombosis, and fatal meningitis. Postoperative magnetic resonance imaging showed blood products within the lesion surrounded by new thin uniform rim of contrast enhancement and diffusion restriction. In conjunction with other therapies, LITT targets often showed stable or reduced local disease. Epilepsy focus LITT produced seizure freedom at 8 months. Preliminary overall median progression-free survival and survival from LITT in tumor patients were 7.6 and 10.9 months, respectively. However, this small cohort has not been followed for a sufficient length of time, necessitating future outcomes studies.

CONCLUSION:

Early peri- and postoperative clinical data demonstrate that LITT is a safe and viable ablative treatment option for intracranial lesions, and may be considered for select patients.

ABBREVIATION:

LITT, laser interstitial thermal therapy

Increased survival using delayed gamma knife radiosurgery for recurrent high-grade glioma: a feasibility study

OBJECTIVE

The current study retrospectively assessed delayed gamma knife radiosurgery (GKRS) in the management of high-grade glioma recurrences.

METHODS

A total of 55 consecutive patients with high-grade glioma comprising 68 World Health Organization (WHO) III and WHO IV were treated with GKRS for local recurrences between 2001 and 2007. All patients had undergone microsurgery and radiochemotherapy, considered as standard therapy for high-grade glioma. Complete follow-up was available in all patients; median follow-up was 17.2 months (2.5-114.2 months). Median tumor volume was 5.2 mL, prescription dose was 20 Gy (14-22 Gy), and median max dose was 45 Gy (30-77.3 Gy).

RESULTS

The patients with WHO III tumors showed a median survival of 49.6 months with and a 2-year survival of 90%. After GKRS of the recurrences, these patients showed a median survival of 24.2 months and a 2-year survival of 50%. The patients with WHO IV tumors had a median survival of 24.5 months with a 2-year survival of 51.4%. After the recurrence was treated with GKRS, the median survival was 11.3 months and a 2-year survival: 22.9% for the WHO IV patients.

CONCLUSION

The current study shows a survival benefit for high-grade glioma recurrences when GKRS was administered after standard therapy. This is a relevant improvement compared with earlier studies that had had not been able to provide a beneficial effect timing radiosurgery in close vicinity to EBRT.

Modulation of PPIX synthesis and accumulation in various normal and glioma cell lines by modification of the cellular signaling and temperature

Effective therapies for malignant gliomas are still elusive and limited survival improvements are provided only by Temozolomide or fluorescence guided resection. The efficacy of photodynamic therapy (PDT) in this indication is limited by the higher sensitivity of normal brain structures compared to glioma necessitating a modulation of its sensitivity. We evaluate the influence of hypothermia and the tyrosine kinase inhibitor Erlotinib on cell's ability to synthesize PPIX following the administration of ALA which was not previously investigated. We demonstrate that both hypothermia and Erlotinib are favorable in PPIX selectivity as only glioma cell lines demonstrate an increased PPIX synthesis, whereas the neuronal and astrocytic synthesis is remaining unaffected. The results are encouraging to consider hypothermia and Erlotinib as adjuvant therapies to increase the PDT therapeutic index between GBM and normal intracranial tissues, as well as to improve contrast in fluorescence guided resection.

Gamma knife surgery as monotherapy with clinically relevant doses prolongs survival in a human GBM xenograft model

OBJECT

Gamma knife surgery (GKS) may be used for recurring glioblastomas (GBMs). However, patients have then usually undergone multimodal treatment, which makes it difficult to specifically validate GKS independent of established treatments. Thus, we developed an experimental brain tumor model to assess the efficacy and radiotoxicity associated with GKS.

METHODS

GBM xenografts were implanted intracerebrally in nude rats, and engraftment was confirmed with MRI. The rats were allocated to GKS, with margin doses of 12 Gy or 18 Gy, or to no treatment. Survival time was recorded, tumor sections were examined, and radiotoxicity was evaluated in a behavioral open field test.

RESULTS

In the first series, survival from the time of implantation was 96 days in treated rats and 72 days in controls (P < 0.001). In a second experiment, survival was 72 days in the treatment group versus 54 days in controls (P < 0.006). Polynuclear macrophages and fibrosis was seen in groups subjected to GKS. Untreated rats with GBM xenografts displayed less mobility than GKS-treated animals in the open field test 4 weeks after treatment (P = 0.04).

CONCLUSION

GKS administered with clinically relevant doses prolongs survival in rats harboring GBM xenografts, and the associated toxicity is mild.

Frameless stereotactic radiosurgery for the treatment of primary intracranial tumours in dogs

Stereotactic radiosurgery (SRS) is a procedure that delivers a single large radiation dose to a well-defined target. Here, we describe a frameless SRS technique suitable for intracranial targets in canines. Medical records of dogs diagnosed with a primary intracranial tumour by imaging or histopathology that underwent SRS were retrospectively reviewed. Frameless SRS was used successfully to treat tumours in 51 dogs with a variety of head sizes and shapes. Tumours diagnosed included 38 meningiomas, 4 pituitary tumours, 4 trigeminal nerve tumours, 3 gliomas, 1 histiocytic sarcoma and 1 choroid plexus tumour. Median survival time was 399 days for all tumours and for dogs with meningiomas; cause-specific survival was 493 days for both cohorts. Acute grade III central nervous system toxicity (altered mentation) occurred in two dogs. Frameless SRS resulted in survival times comparable to conventional radiation therapy, but with fewer acute adverse effects and only a single anaesthetic episode required for therapy.

Anti-PD-1 blockade and stereotactic radiation produce long-term survival in mice with intracranial gliomas

PURPOSE

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults, and radiation is one of the main treatment modalities. However, cure rates remain low despite best available therapies. Immunotherapy is a promising modality that could work synergistically with radiation, which has been shown to increase antigen presentation and promote a proinflammatory tumor microenvironment. Programmed-death-1 (PD-1) is a surface receptor expressed on activated and exhausted T cells, which mediate T cell inhibition upon binding with its ligand PD-L1, expressed on many tumor types including human GBMs. We tested the combination of anti-PD-1 immunotherapy with stereotactic radiosurgery in a mouse orthotopic GBM model.

METHODS AND MATERIALS

We performed intracranial implantation of mouse glioma cell line GL261 transfected with luciferase into C57BL/6 mice. Mice were stratified into 4 treatment groups: (1) control; (2) radiation only; (3) anti-PD-1 antibody only; and (4) radiation plus anti-PD-1 antibody. Overall survival was quantified. The mice were killed on day 21 after implantation to assess immunologic parameters in the brain/tumor, cervical lymph nodes, and spleen.

RESULTS

Improved survival was demonstrated with combination anti-PD-1 therapy plus radiation compared with either modality alone: median survival was 25 days in the control arm, 27 days in the anti-PD-1 antibody arm, 28 days in the radiation arm, and 53 days in the radiation plus anti-PD-1 therapy arm (P<.05 by log-rank Mantle-Cox). Long-term survival was seen only in the combined treatment arm, with a fraction (15%-40%) of animals alive at day 180+ after treatment. Immunologic data on day 21 after implantation showed increased tumor infiltration by cytotoxic T cells (CD8+/interferon-γ+/tumor necrosis factor-α+) and decreased regulatory T cells (CD4+/FOXP3) in the combined treatment group compared with the single modality arms.

CONCLUSIONS

The combination of PD-1 blockade and localized radiation therapy results in long-term survival in mice with orthotopic brain tumors. These studies provide strong preclinical evidence to support combination trials in patients with GBM.

Clinical outcomes of gamma knife radiosurgery in the salvage treatment of patients with recurrent high-grade glioma

BACKGROUND

Previously published randomized evidence did not report a survival advantage for patients diagnosed with grade IV glioma who were treated with stereotactic radiosurgery followed by external beam radiation therapy and chemotherapy when compared to patients treated with external beam radiation therapy and chemotherapy alone. In recent years, gamma knife radiosurgery has become increasingly popular as a salvage treatment modality for patients diagnosed with recurrent high-grade glioma. The purpose of this article is to review the efficacy of gamma knife radiosurgery for patients who suffer from this malignancy.

METHODS

Retrospective, prospective, and randomized clinical studies published between the years 2000 and 2012 analyzing gamma knife radiosurgery for patients with high-grade glioma were reviewed.

RESULTS

After assessing patient age, Karnofsky performance status, tumor histology, and extent of resection, gamma knife radiosurgery is a viable, minimally invasive treatment option for patients diagnosed with recurrent high-grade glioma. The available prospective and retrospective evidence suggests that gamma knife radiosurgery provides patients with a high local tumor control rate and a median survival after tumor recurrence ranging from 13 to 26 months. Gamma knife radiosurgery followed by chemotherapy for recurrent high-grade glioma may provide select patients with increased levels of survival. However, further investigation into this matter is needed due to the limited number of published reports. Additional clinical research is also needed to analyze the efficacy and radiation-related toxicities of fractionated gamma knife radiosurgery due to its potential to limit treatment-associated morbidity.

CONCLUSIONS

Gamma knife radiosurgery is a safe and effective treatment option for select patients diagnosed with recurrent high-grade glioma. Although treatment outcomes have improved, further evidence in the form of phase III randomized trials is needed to assess the durability of treating patients in specific clinical situations.

Nanotechnology-novel therapeutics for CNS disorders

Research into treatments for diseases of the CNS has made impressive strides in the past few decades, but therapeutic options are limited for many patients with CNS disorders. Nanotechnology has emerged as an exciting and promising new means of treating neurological disease, with the potential to fundamentally change the way we approach CNS-targeted therapeutics. Molecules can be nanoengineered to cross the blood-brain barrier, target specific cell or signalling systems, respond to endogenous stimuli, or act as vehicles for gene delivery, or as a matrix to promote axon elongation and support cell survival. The wide variety of available nanotechnologies allows the selection of a nanoscale material with the characteristics best suited to the therapeutic challenges posed by an individual CNS disorder. In this Review, we describe recent advances in the development of nanotechnology for the treatment of neurological disorders-in particular, neurodegenerative disease and malignant brain tumours-and for the promotion of neuroregeneration.

γ knife surgery versus reoperation for recurrent glioblastoma multiforme

BACKGROUND

The optimal management of patients with recurrent glioblastoma multiforme (GBM) is a subject of controversy. These patients may be candidates for both reoperation and/or gamma knife surgery (GKS). Few studies have addressed the role of GKS for relapsing gliomas, and the results have not been compared with reoperation. To validate the efficacy and safety of GKS, we compared the survival and complication rates of GKS and reoperation for recurrent GBMs.

METHODS

This study retrospectively reviewed 77 consecutive patients with histopathologically confirmed GBMs retreated for recurrent GBM between 1996 and 2007. Thirty-two patients underwent GKS, 26 reoperation and 19 both procedures.

RESULTS

The median time from the second intervention to tumor progression was longer after GKS than after resection, P = 0.009. Median survival after retreatment was 12 months for the 51 patients receiving GKS compared with 6 months for reoperation only (P = 0.001, hazard ratio [HR] 2.4), and 19 months versus 16 months from the time of primary diagnosis (P = 0.021, HR 1.8). A multivariate analysis adjusted for possible confounding factors (tumor volume, recursive partitioning analysis class, neurological deficits, time to recurrence, adjuvant therapy, and tumor location) showed significantly longer survival for patients treated with GKS, both from retreatment (P = 0.013, HR 4.1) and from primary diagnosis (P = 0.002, HR 5.8). The adjusted results were still significant after separate analysis according to tumor volume <5 mL, 5 to 20 mL, and >20 mL. The complications rate was 9.8% after GKS and 25.2% after reoperation.

CONCLUSIONS

GKS may be an alternative to open surgery for small GBMs at the time of recurrences, with a significantly lower complication rate and a possible survival benefit compared with reoperation.

Role of stereotactic radiosurgery and fractionated stereotactic radiotherapy for the treatment of recurrent glioblastoma multiforme

Glioblastoma multiforme (GBM) is a devastating malignant brain tumor characterized by resistance to available therapeutic approaches and relentless malignant progression that includes widespread intracranial invasion, destruction of normal brain tissue, progressive disability, and death. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) are increasingly used in patients with recurrent GBM to complement traditional treatments such as resection, conventional external beam radiotherapy, and chemotherapy. Both SRS and fSRT are powerful noninvasive therapeutic modalities well suited to treat focal neoplastic lesions through the delivery of precise, highdose radiation. Although no randomized clinical trials have been performed, a variety of retrospective studies have been focused on the use of SRS and fSRT for recurrent GBMs. In addition, state-of-the-art neuroimaging techniques, such as MR spectroscopic imaging, diffusion tensor tractography, and nuclear medicine imaging, have enhanced treatment planning methods leading to potentially improved clinical outcomes. In this paper the authors reviewed the current applications and efficacy of SRS and fSRT in the treatment of GBM, highlighting the value of these therapies for recurrent focal disease.