Gamma Knife Stereotactic Radiosurgery in Combination with Bevacizumab for Recurrent Glioblastoma

Treatment advances in high-grade gliomas

High-grade gliomas (HGG) pose significant challenges in modern tumour therapy due to the distinct biological properties and limitations of the blood-brain barrier. This review discusses recent advancements in HGG treatment, particularly in the context of immunotherapy and cellular therapy. Initially, treatment strategies focus on targeting tumour cells guided by the molecular characteristics of various gliomas, encompassing chemotherapy, radiotherapy and targeted therapy for enhanced precision. Additionally, technological enhancements are augmenting traditional treatment modalities. Furthermore, immunotherapy, emphasising comprehensive tumour management, has gained widespread attention. Immune checkpoint inhibitors, vaccines and CAR-T cells exhibit promising efficacy against recurrent HGG. Moreover, emerging therapies such as tumour treating fields (TTFields) offer additional treatment avenues for patients with HGG. The combination of diverse treatments holds promise for improving the prognosis of HGG, particularly in cases of recurrence.

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.

Advances in Glioblastoma Therapy: An Update on Current Approaches

Glioblastoma multiforme (GBM) is a primary malignant brain tumor characterized by a high grade of malignancy and an extremely unfavorable prognosis. The current efficacy of established treatments for GBM is insufficient, necessitating the prompt development of novel therapeutic approaches. The progress made in the fundamental scientific understanding of GBM is swiftly translated into more advanced stages of therapeutic studies. Despite extensive efforts to identify new therapeutic approaches, GBM exhibits a high mortality rate. The current efficacy of treatments for GBM patients is insufficient due to factors such as tumor heterogeneity, the blood-brain barrier, glioma stem cells, drug efflux pumps, and DNA damage repair mechanisms. Considering this, pharmacological cocktail therapy has demonstrated a growing efficacy in addressing these challenges. Towards this, various forms of immunotherapy, including the immune checkpoint blockade, chimeric antigen receptor T (CAR T) cell therapy, oncolytic virotherapy, and vaccine therapy have emerged as potential strategies for enhancing the prognosis of GBM. Current investigations are focused on exploring combination therapies to mitigate undesirable side effects and enhance immune responses against tumors. Furthermore, clinical trials are underway to evaluate the efficacy of several strategies to circumvent the blood-brain barrier (BBB) to achieve targeted delivery in patients suffering from recurrent GBM. In this review, we have described the biological and molecular targets for GBM therapy, pharmacologic therapy status, prominent resistance mechanisms, and new treatment approaches. We also discuss these promising therapeutic approaches to assess prospective innovative therapeutic agents and evaluated the present state of preclinical and clinical studies in GBM treatment. Overall, this review attempts to provide comprehensive information on the current status of GBM therapy.

The evolving role of reirradiation in the management of recurrent brain tumors

Despite aggressive management consisting of surgery, radiation therapy (RT), and systemic therapy given alone or in combination, a significant proportion of patients with brain tumors will experience tumor recurrence. For these patients, no standard of care exists and management of either primary or metastatic recurrent tumors remains challenging.Advances in imaging and RT technology have enabled more precise tumor localization and dose delivery, leading to a reduction in the volume of health brain tissue exposed to high radiation doses. Radiation techniques have evolved from three-dimensional (3-D) conformal RT to the development of sophisticated techniques, including intensity modulated radiation therapy (IMRT), volumetric arc therapy (VMAT), and stereotactic techniques, either stereotactic radiosurgery (SRS) or stereotactic radiotherapy (SRT). Several studies have suggested that a second course of RT is a feasible treatment option in patients with a recurrent tumor; however, survival benefit and treatment related toxicity of reirradiation, given alone or in combination with other focal or systemic therapies, remain a controversial issue.We provide a critical overview of the current clinical status and technical challenges of reirradiation in patients with both recurrent primary brain tumors, such as gliomas, ependymomas, medulloblastomas, and meningiomas, and brain metastases. Relevant clinical questions such as the appropriate radiation technique and patient selection, the optimal radiation dose and fractionation, tolerance of the brain to a second course of RT, and the risk of adverse radiation effects have been critically discussed.

Stereotactic Radiosurgery for Contrast-Enhancing Satellite Nodules in Recurrent Glioblastoma: A Rare Case Series From a Single Institution

Introduction Glioblastoma (GBM) is the most common malignant adult brain tumor and is invariably fatal. The standard treatment for GBM involves resection where possible, followed by chemoradiation per Stupp's protocol. We frequently use stereotactic radiosurgery (SRS) as a single-fraction treatment for small (volume ≤ 1cc) nodular recurrent GBM to the contrast-enhancing target on T1 MRI scan. In this paper, we aimed to evaluate the safety and efficacy of SRS for patients with contrast-enhancing satellite nodules in recurrent GBM. Methods This retrospective study analyzed the clinical and radiological outcomes of five patients who underwent CyberKnife (Accuray Inc., Sunnyvale, California) SRS at the institute between 2013 and 2022. Results From 96 patients receiving SRS for GBM, five (four males, one female; median age 53) had nine distinct new satellite lesions on MRI, separate from their primary tumor beds. Those nine lesions were treated with a median margin dose of 20 Gy in a single fraction. The three-, six, and 12-month local tumor control rates were 77.8%, 66.7%, and 26.7%, respectively. Median progression-free survival (PFS) was seven months, median overall survival following SRS was 10 months, and median overall survival (OS) was 35 months. Interestingly, the only lesion that did not show radiological progression was separate from the T2-fluid attenuated inversion recovery (FLAIR) signal of the main tumor. Conclusion Our SRS treatment outcomes for recurrent GBM satellite lesions are consistent with existing findings. However, in a unique case, a satellite nodule distinct from the primary tumor's T2-FLAIR signal and treated with an enlarged target volume showed promising control until the patient's demise. This observation suggests potential research avenues, given the limited strategies for 'multicentric' GBM lesions.

Use of Bevacizumab in recurrent glioblastoma: a scoping review and evidence map

BACKGROUND

Glioblastoma (GBM) is the most malignant primary tumor in the brain, with poor prognosis and limited effective therapies. Although Bevacizumab (BEV) has shown promise in extending progression-free survival (PFS) treating GBM, there is no evidence for its ability to prolong overall survival (OS). Given the uncertainty surrounding BEV treatment strategies, we aimed to provide an evidence map associated with BEV therapy for recurrent GBM (rGBM).

METHODS

PubMed, Embase, and the Cochrane Library were searched for the period from January 1, 1970, to March 1, 2022, for studies reporting the prognoses of patients with rGBM receiving BEV. The primary endpoints were overall survival (OS) and quality of life (QoL). The secondary endpoints were PFS, steroid use reduction, and risk of adverse effects. A scoping review and an evidence map were conducted to explore the optimal BEV treatment (including combination regimen, dosage, and window of opportunity).

RESULTS

Patients with rGBM could gain benefits in PFS, palliative, and cognitive advantages from BEV treatment, although the OS benefits could not be verified with high-quality evidence. Furthermore, BEV combined therapy (especially with lomustine and radiotherapy) showed higher efficacy than BEV monotherapy in the survival of patients with rGBM. Specific molecular alterations (IDH mutation status) and clinical features (large tumor burden and double-positive sign) could predict better responses to BEV administration. A low dosage of BEV showed equal efficacy to the recommended dose, but the optimal opportunity window for BEV administration remains unclear.

CONCLUSIONS

Although OS benefits from BEV-containing regimens could not be verified in this scoping review, the PFS benefits and side effects control supported BEV application in rGBM. Combining BEV with novel treatments like tumor-treating field (TTF) and administration at first recurrence may optimize the therapeutic efficacy. rGBM with a low apparent diffusion coefficient (ADCL), large tumor burden, or IDH mutation is more likely to benefit from BEV treatment. High-quality studies are warranted to explore the combination modality and identify BEV-response subpopulations to maximize benefits.

Molecular Pathways Implicated in Radioresistance of Glioblastoma Multiforme: What Is the Role of Extracellular Vesicles?

Glioblastoma multiforme (GBM) is a primary brain tumor that is very aggressive, resistant to treatment, and characterized by a high degree of anaplasia and proliferation. Routine treatment includes ablative surgery, chemotherapy, and radiotherapy. However, GMB rapidly relapses and develops radioresistance. Here, we briefly review the mechanisms underpinning radioresistance and discuss research to stop it and install anti-tumor defenses. Factors that participate in radioresistance are varied and include stem cells, tumor heterogeneity, tumor microenvironment, hypoxia, metabolic reprogramming, the chaperone system, non-coding RNAs, DNA repair, and extracellular vesicles (EVs). We direct our attention toward EVs because they are emerging as promising candidates as diagnostic and prognostication tools and as the basis for developing nanodevices for delivering anti-cancer agents directly into the tumor mass. EVs are relatively easy to obtain and manipulate to endow them with the desired anti-cancer properties and to administer them using minimally invasive procedures. Thus, isolating EVs from a GBM patient, supplying them with the necessary anti-cancer agent and the capability of recognizing a specified tissue-cell target, and reinjecting them into the original donor appears, at this time, as a reachable objective of personalized medicine.

Bevacizumab combined with re-irradiation in recurrent glioblastoma

Background

Glioblastoma is characterized by rich vasculature and abnormal vascular structure and function. Currently, there is no standard treatment for recurrent glioblastoma (rGBM). Bevacizumab (BEV) has established role of inhibiting neovascularization, alleviating hypoxia in the tumor area and activating the immune microenvironment. BEV may exert synergistic effects with re-irradiation (re-RT) to improve the tumor microenvironment for rGBM.

Purpose

The purpose of this study was to evaluate the safety, tolerability, and efficacy of a combination of BEV and re-RT for rGBM treatment.

Methods

In this retrospective study, a total of 26 rGBM patients with surgical pathologically confirmed glioblastoma and at least one event of recurrence were enrolled. All patients were treated with re-RT in combination with BEV. BEV was administered until progression or serious adverse events.

Results

Median follow-up was 21.9 months for all patients, whereas median progression-free survival (PFS) was 8.0 months (95% confidence interval [CI]: 6.5–9.5 months). In addition, the 6-month and 1-year PFS rates were 65.4% and 28.2%, respectively. The median overall survival (OS), 6-month OS rate, and 1-year OS rate were 13.6 months (95% CI: 10.2–17.0 months), 92.3%, and 67.5%, respectively. The patient showed good tolerance during the treatment with no grade > 3 grade side event and radiation necrosis occurrence rate of 0%. Combined treatment of gross total resection (GTR) before re-RT and concurrent temozolomide during re-RT was an independent prognostic factor that affected both OS and PFS in the whole cohort (OS: 0.067, 95% CI: 0.009–0.521, p = 0.010; PFS: 0.238, 95% CI: 0.076–0.744, p = 0.038).

Conclusion

In this study, re-RT combined with concurrent and maintenance BEV treatment was safe, tolerable, and effective in rGBM patients. Moreover, GTR before re-RT and selective concurrent temozolomide could further improve patient PFS and OS.

Stereotactic radiosurgery for glioblastoma considering tumor genetic profiles: an international multicenter study

OBJECTIVE

Molecular profiles, such as isocitrate dehydrogenase (IDH) mutation and O6-methylguanine-DNA methyltransferase (MGMT) methylation status, have important prognostic roles for glioblastoma patients. The authors studied the efficacy and safety of stereotactic radiosurgery (SRS) for glioblastoma patients with consideration of molecular tumor profiles.

METHODS

For this retrospective observational multiinstitutional study, the authors pooled consecutive patients who were treated using SRS for glioblastoma at eight institutions participating in the International Radiosurgery Research Foundation. They evaluated predictors of overall and progression-free survival with consideration of IDH mutation and MGMT methylation status.

RESULTS

Ninety-six patients (median age 56 years) underwent SRS (median dose 15 Gy and median treatment volume 5.53 cm3) at 147 tumor sites (range 1 to 7). The majority of patients underwent prior fractionated radiation therapy (92%) and temozolomide chemotherapy (98%). Most patients were treated at recurrence (85%), and boost SRS was used for 12% of patients. The majority of patients harbored IDH wild-type (82%) and MGMT-methylated (62%) tumors. Molecular data were unavailable for 33 patients. Median survival durations after SRS were similar between patients harboring IDH wild-type tumors and those with IDH mutant tumors (9.0 months vs 11 months, respectively), as well as between those with MGMT-methylated tumors and those with MGMT-unmethylated tumors (9.8 vs. 9.0 months, respectively). Prescription dose > 15 Gy (OR 0.367, 95% CI 0.190-0.709, p = 0.003) and treatment volume > 5 cm3 (OR 1.036, 95% CI 1.007-1.065, p = 0.014) predicted overall survival after controlling for age and IDH status. Treatment volume > 5 cm3 (OR 2.215, 95% CI 1.159-4.234, p = 0.02) and absence of gross-total resection (OR 0.403, 95% CI 0.208-0.781, p = 0.007) were associated with inferior local control of SRS-treated lesions in multivariate models. Nine patients experienced adverse radiation events after SRS, and 7 patients developed radiation necrosis at 59 to 395 days after SRS.

CONCLUSIONS

Post-SRS survival was similar as a function of IDH mutation and MGMT promoter methylation status, suggesting that molecular profiles of glioblastoma should be considered when selecting candidates for SRS. SRS prescription dose > 15 Gy and treatment volume ≤ 5 cm3 were associated with longer survival, independent of age and IDH status. Prior gross-total resection and smaller treatment volume were associated with superior local control.

Synchronous glioblastoma and brain metastases: illustrative case

BACKGROUND

Radiosurgical treatment of brain metastases is usually performed without brain tissue confirmation. While it is extremely rare for glioblastoma to develop concurrently in patients with brain metastases, they can look radiographically similar, and recognition is important because it alters management and prognosis. The synchronous presence of brain metastases and glioblastoma has not been published to date in the literature, making this a rare illustrative case.

OBSERVATIONS

A 70-year-old female had lung biopsy-proven metastatic lung adenocarcinoma and multiple brain metastases. Her treatment course included initial carboplatin, pemetrexed, and bevacizumab followed by maintenance nivolumab, and she underwent stereotactic radiosurgery to the multiple brain metastases. During interval radiological surveillance, one lesion in the right temporal lobe was noted to slowly progress associated with development of significant perilesional edema causing midline shift despite repeated stereotactic radiosurgical treatments. Biopsy of this lesion revealed glioblastoma, IDH wildtype.

LESSONS

Glioblastomas and brain metastases have similar radiological features, so the possibility of incorrect diagnosis needs to be considered for all lesions with interval growth poststereotactic radiosurgery. Biopsy and/or resection/laser ablation should be considered prior to reirradiation.

Metastatic Neoplasm Volume Kinetics Following Two-Staged Stereotactic Radiosurgery

INTRODUCTION

Multisession staged stereotactic radiosurgery (2-SSRS) represents an alternative approach for management of large brain metastases (LBMs), with potential advantages over fractionated SRS. We investigated the clinical efficacy and safety of 2-SSRS in patients with LBMs.

METHODS

LBMs patients treated with 2-SSRS between 2014-2020 were evaluated. Demographic, clinical, and radiologic information was obtained. Volumetric measurements at first SSRS, second SSRS, and follow-up imaging studies were obtained. Characteristics that might predict response to 2-SSRS were evaluated through Fischer-exact or Mann-Whitney U test.

RESULTS

Twenty-four patients with 26 LBMs were included in the study. Median marginal doses for first and second SSRS were 15 Gy (14-18 Gy) and 15 Gy (12-16 Gy), respectively. Median tumor volumes at first SSRS, second SSRS, and 3-month follow-up were 8.1 cm³ (1.5-28.5 cm³), 3.3 cm³ (0.8-26.1 cm³), and 2.2 cm³ (0.2-10.1 cm³), respectively. Overall, 24/26 lesions (92%) demonstrated early local control following the first SSRS with 17 lesions (71%) demonstrating a decrease of >30% in the T1 post-contrast MRI volume before the second SSRS and 3 lesions (12%) remaining stable. Eventually, four lesions showed disease progression after 2-SSRS. The median time to local progression was not reached and the median time to intracranial progression was 9.1 months.

CONCLUSIONS

Our study supports the effectiveness and safety of 2-SSRS as a treatment modality for patients with large, symptomatic brain metastases, especially in poor surgical candidates. The local failure rate and low occurrence of adverse effects are comparable to other staged radiosurgery studies.

The effectiveness of gamma knife radiosurgery for the management of residual high-grade gliomas: A single institutional study

High-grade gliomas (HGGs) are presently managed via surgical resection, external beam radiation therapy (EBRT), and chemotherapy. Although Gamma Knife radiosurgery (GKRS) is currently used to manage HGGs, it has not been considered standard care. This paper aims to compare the contribution of GKRS to clinical outcomes in patients in which gross total resection (GTR) cannot be achieved. We retrospectively reviewed the data of 99 patients with HGG (World Health Organization (WHO) grade III and IV) from two groups: group 1 consisted of 68 patients for which only EBRT was administered, and group 2 consisted of 31 patients for which EBRT and GKRS were administered. Patient demographic data, the extent of resection, IDH mutation, radiation dosage, progression-free survival (PFS), overall survival (OS), and follow-up time were recorded and compared across groups. The grade III/IV tumor ratio was 10/58 and 10/21 in groups 1 and 2, respectively. In group 2, PFS and OS were higher than in group 1 (P = 0.030 and 0.021). The mean follow-up time was 15.02 ± 11.8 (3-52) and 18.9 ± 98.6 (7-43) months in groups 1 and 2, respectively. In addition to the standard management of HGGs in patients without GTR, boost GKRS during the early postoperative period is beneficial for increasing PFS and OS.

Stereotactic radiosurgery for IDH wild type glioblastoma: an international, multicenter study

OBJECTIVE

Isocitrate dehydrogenase (IDH) mutation status is recommended used for diagnosis and prognostication of glioblastoma patients. We studied efficacy and safety of stereotactic radiosurgery (SRS) for patients with recurrent IDH-wt glioblastoma.

METHODS

Consecutive patients treated with SRS for IDH-wt glioblastoma were pooled for this retrospective observational international multi-institutional study from institutions participating in the International Radiosurgery Research Foundation.

RESULTS

Sixty patients (median age 61 years) underwent SRS (median dose 15 Gy and median treatment volume: 7.01 cm³) for IDH-wt glioblastoma. All patients had histories of surgery and chemotherapy with temozolomide, and 98% underwent fractionated radiation therapy. MGMT status was available for 42 patients, of which half of patients had MGMT mutant glioblastomas. During median post-SRS imaging follow-up of 6 months, 52% of patients experienced tumor progression. Median post-SRS progression free survival was 4 months. SRS prescription dose of > 14 Gy predicted longer progression free survival [HR 0.357 95% (0.164-0.777) p = 0.009]. Fifty-percent of patients died during post-SRS clinical follow-up that ranged from 1 to 33 months. SRS treatment volume of > 5 cc emerged as an independent predictor of shorter post-SRS overall survival [HR 2.802 95% CI (1.219-6.444) p = 0.02]. Adverse radiation events (ARE) suggestive of radiation necrosis were diagnosed in 6/55 (10%) patients and were managed conservatively in the majority of patients.

CONCLUSIONS

SRS prescription dose of > 14 Gy is associated with longer progression free survival while tumor volume of > 5 cc is associated with shorter overall survival after SRS for IDH-wt glioblastomas. AREs are rare and are typically managed conservatively.

Glioblastoma: What can we do for these patients today and what will we be able to do in the future?

Glioblastoma multiforme (GBM) is an extremely aggressive primary human brain tumor. The median survival of GBM patients is 15 months in case of completing the modern complex treatment protocol. Chemotherapy can help to extend the life expectancy of patients. GBM treatment resistance is associated with cancer stem cells (CSCs). The present paper analyses the main reasons for ineffectiveness of the existing GBM treatment methods and suggests treating CSCs as a complex phenomenon, resulting from the coordinated interaction of normal stem cells and cancer cells (CCs) in immunosuppressive microsurroundings. The GBM treatment strategy is suggested not for only suppressing strategically important signaling pathways in CCs, but also for regulating interaction between normal stem cells and cancer cells. The paper considers the issue of controlling penetrability of the blood-brain barrier that is one of the main challenges in neuro-oncology. Also, the paper suggests the ways of extending life expectancy of GBM patients today and prospects for the near future.

Accelerator-based BNCT for patients with recurrent glioblastoma: a multicenter phase II study

Background

Boron neutron capture therapy (BNCT) utilizes tumor-selective particle radiation. This study aimed to assess the safety and efficacy of accelerator-based BNCT (AB-BNCT) using a cyclotron-based neutron generator (BNCT 30) and ¹⁰B-boronophenylalanine (SPM-011) in patients with recurrent malignant glioma (MG) (primarily glioblastoma [GB]).

Methods

This multi-institutional, open-label, phase II clinical trial involved 27 recurrent MG cases, including 24 GB cases, who were enrolled from February 2016 to June 2018. The study was conducted using the abovementioned AB-BNCT system, with 500 mg/kg SPM-011 (study code: JG002). The patients were bevacizumab-naïve and had recurrent MG after standard treatment. The primary endpoint was the 1-year survival rate, and the secondary endpoints were overall survival (OS) and progression-free survival (PFS). Results were compared to those of a previous Japanese domestic bevacizumab trial for recurrent GB (JO22506).

Results

The 1-year survival rate and median OS of the recurrent GB cases in this trial were 79.2% (95% CI: 57.0–90.8) and 18.9 months (95% CI: 12.9–not estimable), respectively, whereas those of JO22506 were 34.5% (90% CI: 20.0–49.0) and 10.5 months (95% CI: 8.2–12.4), respectively. The median PFS was 0.9 months (95% CI: 0.8–1.0) by the RANO criteria. The most prominent adverse event was brain edema. Twenty-one of 27 cases were treated with bevacizumab following progressive disease.

Conclusions

AB-BNCT demonstrated acceptable safety and prolonged survival for recurrent MG. AB-BNCT may increase the risk of brain edema due to re-irradiation for recurrent MG; however, this appears to be controlled well with bevacizumab.

PTEN mutations predict benefit from tumor treating fields (TTFields) therapy in patients with recurrent glioblastoma

INTRODUCTION

Optimal treatment for recurrent glioblastoma isocitrate dehydrogenase 1 and 2 wild-type (rGBM IDH-WT) is not standardized, resulting in multiple therapeutic approaches. A phase III clinical trial showed that tumor treating fields (TTFields) monotherapy provided comparable survival benefits to physician's chemotherapy choice in rGBM. However, patients did not equally benefit from TTFields, highlighting the importance of identifying predictive biomarkers of TTFields efficacy.

METHODS

A retrospective review of an institutional database with 530 patients with infiltrating gliomas was performed. Patients with IDH-WT rGBM receiving TTFields at first recurrence were included. Tumors were evaluated by next-generation sequencing for mutations in 205 cancer-related genes. Post-progression survival (PPS) was examined using the log-rank test and multivariate Cox-regression analysis.

RESULTS

149 rGBM patients were identified of which 29 (19%) were treated with TTFields. No significant difference in median PPS was observed between rGBM patients who received versus did not receive TTFields (13.9 versus 10.9 months, p = 0.068). However, within the TTFields-treated group (n = 29), PPS was improved in PTEN-mutant (n = 14) versus PTEN-WT (n = 15) rGBM, (22.2 versus 11.6 months, p = 0.017). Within the PTEN-mutant group (n = 70, 47%), patients treated with TTFields (n = 14) had longer median PPS (22.2 versus 9.3 months, p = 0.005). No PPS benefit was observed in PTEN-WT patients receiving TTFields (n = 79, 53%).

CONCLUSIONS

TTFields therapy conferred a significant PPS benefit in PTEN-mutant rGBM. Understanding the molecular mechanisms underpinning the differences in response to TTFields therapy could help elucidate the mechanism of action of TTFields and identify the rGBM patients most likely to benefit from this therapeutic option.

Perspective of mesenchymal transformation in glioblastoma

Despite aggressive multimodal treatment, glioblastoma (GBM), a grade IV primary brain tumor, still portends a poor prognosis with a median overall survival of 12–16 months. The complexity of GBM treatment mainly lies in the inter- and intra-tumoral heterogeneity, which largely contributes to the treatment-refractory and recurrent nature of GBM. By paving the road towards the development of personalized medicine for GBM patients, the cancer genome atlas classification scheme of GBM into distinct transcriptional subtypes has been considered an invaluable approach to overcoming this heterogeneity. Among the identified transcriptional subtypes, the mesenchymal subtype has been found associated with more aggressive, invasive, angiogenic, hypoxic, necrotic, inflammatory, and multitherapy-resistant features than other transcriptional subtypes. Accordingly, mesenchymal GBM patients were found to exhibit worse prognosis than other subtypes when patients with high transcriptional heterogeneity were excluded. Furthermore, identification of the master mesenchymal regulators and their downstream signaling pathways has not only increased our understanding of the complex regulatory transcriptional networks of mesenchymal GBM, but also has generated a list of potent inhibitors for clinical trials. Importantly, the mesenchymal transition of GBM has been found to be tightly associated with treatment-induced phenotypic changes in recurrence. Together, these findings indicate that elucidating the governing and plastic transcriptomic natures of mesenchymal GBM is critical in order to develop novel and selective therapeutic strategies that can improve both patient care and clinical outcomes. Thus, the focus of our review will be on the recent advances in the understanding of the transcriptome of mesenchymal GBM and discuss microenvironmental, metabolic, and treatment-related factors as critical components through which the mesenchymal signature may be acquired. We also take into consideration the transcriptomic plasticity of GBM to discuss the future perspectives in employing selective therapeutic strategies against mesenchymal GBM.

Genomic alterations predictive of response to radiosurgery in recurrent IDH-WT glioblastoma

INTRODUCTION

Despite aggressive treatment, glioblastoma invariably recurs. The optimal treatment for recurrent glioblastoma (rGBM) is not well defined. Stereotactic radiosurgery (SRS) for rGBM has demonstrated favorable outcomes for selected patients; however, its efficacy in molecular GBM subtypes is unknown. We sought to identify genetic alterations that predict response/outcomes from SRS in rGBM-IDH-wild-type (IDH-WT).

METHODS

rGBM-IDH-WT patients undergoing SRS at first recurrence and tested by next-generation sequencing (NGS) were reviewed (2009-2018). Demographic, clinical, and molecular characteristics were evaluated. NGS interrogating 205-genes was performed. Primary outcome was survival from GK-SRS assessed by Kaplan-Meier method and multivariable Cox proportional-hazards.

RESULTS

Sixty-three lesions (43-patients) were treated at 1st recurrence. Median age was 61-years. All patients were treated with resection and chemoradiotherapy. Median time from diagnosis to 1st recurrence was 8.7-months. Median cumulative volume was 2.895 cm3 and SRS median marginal dose was 18 Gy (median isodose-54%). Bevacizumab was administered in 81.4% patients. PFS from SRS was 12.9-months. Survival from SRS was 18.2-months. PTEN-mutant patients had a longer PFS (p = 0.049) and survival from SRS (p = 0.013) in multivariable analysis. Although no statistically significant PTEN-mutants patients had higher frequency of radiation necrosis (21.4% vs. 3.4%) and lower in-field recurrence (28.6% vs. 37.9%) compared to PTEN-WT patients.

CONCLUSIONS

SRS is a safe and effective treatment option for selected rGBM-IDH-WT patients following first recurrence. rGBM-IDH-WT harboring PTEN-mutation have improved survival with salvage SRS compared to PTEN-WT patients. PTEN may be used as a molecular biomarker to identify a subset of rGBM patients who may benefit the most from SRS.

Current status and recent advances in reirradiation of glioblastoma

Despite aggressive management consisting of maximal safe surgical resection followed by external beam radiation therapy (60 Gy/30 fractions) with concomitant and adjuvant temozolomide, approximately 90% of WHO grade IV gliomas (glioblastomas, GBM) will recur locally within 2 years. For patients with recurrent GBM, no standard of care exists. Thanks to the continuous improvement in radiation science and technology, reirradiation has emerged as feasible approach for patients with brain tumors. Using stereotactic radiosurgery (SRS) or stereotactic radiotherapy (SRT), either hypofractionated or conventionally fractionated schedules, several studies have suggested survival benefits following reirradiation of patients with recurrent GBM; however, there are still questions to be answered about the efficacy and toxicity associated with a second course of radiation. We provide a clinical overview on current status and recent advances in reirradiation of GBM, addressing relevant clinical questions such as the appropriate patient selection and radiation technique, optimal dose fractionation, reirradiation tolerance of the brain and the risk of radiation necrosis.

Metastatic renal cell carcinoma to the brain: optimizing patient selection for gamma knife radiosurgery

INTRODUCTION

The effects of single-fraction gamma knife radiosurgery (sf-GKRS) on patients with renal cell carcinoma (RCC) brain metastases (BM) in the era of targeted agents (TA) and immune checkpoint inhibitors (ICI) are insufficiently studied.

METHODS AND MATERIALS

Clear cell metastatic RCC patients treated with sf-GKRS due to BM in 2005-2014 at three European centres were retrospectively analysed (n = 43). Median follow-up was 56 months. Ninety-five percent had prior nephrectomy, 53% synchronous metastasis and 86% extracranial disease at first sf-GKRS. Karnofsky performance status (KPS) ranged from 60 to 100%. Outcome measures were overall survival (OS), local control (LC) and adverse radiation effects (ARE).

RESULTS

One hundred and ninety-four targets were irradiated. The median number of targets at first sf-GKRS was two. The median prescription dose was 22.0 Gy. Thirty-seven percent had repeated sf-GKRS. Eighty-eight percent received TA. LC rates at 12 and 18 months were 97% and 90%. Median OS from the first sf-GKRS was 15.7 months. Low serum albumin (HR for death 5.3), corticosteroid use pre-sf-GKRS (HR for death 5.8) and KPS < 80 (HR for death 9.1) were independently associated with worse OS. No further prognostic information was gleaned from MSKCC risk group, synchronous metastasis, age, number of BM or extracranial metastases. Other prognostic scores for BM radiosurgery, including DS-GPA, renal-GPA, LLV-SIR and CITV-SIR, again, did not add further prognostic value. ARE were seldom symptomatic and were associated with tumour volume, 10-Gy volume and pre-treatment perifocal oedema. ARE were less common among patients treated with TA within 1 month of sf-GKRS.

CONCLUSIONS

We identified albumin, corticosteroid use and KPS as independent prognostic factors for sf-GKRS of clear cell RCC BM. Studies focusing on the prognostic significance of albumin in sf-GKRS are rare. Further studies with a larger number of patients are warranted to confirm the above analytical outcome. Also, in keeping with previous studies, our data showed optimal rates of local tumour control and limited toxicity post radiosurgery, rendering GKRS the tool of choice in the management of RCC BM.

Glioblastoma Break-in; Try Something New

Context: Glioblastoma is the most invasive brain tumor with a poor prognosis and rapid progression. The standard therapy (surgical resection, adjuvant chemotherapy, and radiotherapy) ensures survival only up to 18 months. In this article, we focus on innovative types of radiotherapy, various combinations of temozolomide with novel substances, and methods of their administration and vector delivery to tumor cells. Evidence Acquisition: For a detailed study of the various options for chemotherapy and radiotherapy, Elsevier, NCBI MedLine, Scopus, Google Scholar, Embase, Web of Science, The Cochrane Library, EMBASE, Global Health, CyberLeninka, and RSCI databases were analyzed. Results: The most available method is oral or intravenous administration of temozolomide. More efficient is the combined chemotherapy of temozolomide with innovative drugs and substances such as lomustine, histone deacetylase inhibitors, and chloroquine, as well as olaparib. These combinations improve patient survival and are effective in the treatment of resistant tumors. Compared to standard fractionated radiotherapy (60 Gy, 30 fractions, 6 weeks), hypofractionated is more effective for elderly patients due to lack of toxicity; brachytherapy reduces the risk of glioblastoma recurrence, while radiosurgery with bevacizumab is more effective against recurrent or inoperable tumors. Currently, the most effective treatment is considered to be the intranasal administration of anti-Ephrin A3 (anti-EPHA3)-modified containing temozolomide butyl ester-loaded (TBE-loaded) poly lactide-co-glycolide nanoparticles (P-NPs) coated with N-trimethylated chitosan (TMC) to overcome nasociliary clearance. Conclusions: New radiotherapeutic methods significantly increase the survival rates of glioblastoma patients. With some improvement, it may lead to the elimination of all tumor cells leaving the healthy alive. New chemotherapeutic drugs show impressive results with adjuvant temozolomide. Anti-EPHA3-modified TBE-loaded P-NPs coated with TMC have high absorption specificity and kill glioblastoma cells effectively. A new “step forward” may become a medicine of the future, which reduces the specific accumulation of nanoparticles in the lungs, but simultaneously does not affect specific absorption by tumor cells.

Role of Ethnicity and Geographic Location on Glioblastoma IDH1/IDH2 Mutations

BACKGROUND

Previous studies have demonstrated possible differences in glioblastoma (GBM) survival attributable to ethnicity. The goal of this study was to quantify oncogenic differences and evaluate the overall survival (OS) and progression-free survival (PFS) differences in GBM patients across race/ethnicity using both population-based surveillance and institutional data sets from the United States (US) and Mexico.

METHODS

Retrospective cohort study comprising the Texas Cancer Registry (TCR, n = 4134) and referral institutions located in US (n = 254) and Mexico (n = 47) were evaluated. Primary outcomes include OS and PFS. Oncogenic differences attributable to ethnicity were assessed. IDH1/IDH2 status was evaluated by sequencing in US and Mexico samples. Kaplan-Meier and Cox proportional hazards regression for survival analysis.

RESULTS

A total of 4134 GBM patients were identified from the TCR data set, ethnicity comparison demonstrated that Hispanic patients were diagnosed at a significantly younger age compared to non-Hispanic white patients (NHW) (median: 58 vs. 62, P < 0.001) and had improved OS (hazard ratio: 0.82, P < 0.001). In the oncogenic analysis, we observed a significant enrichment of IDH1/IDH2 mutations in Mexican Hispanic patients compared to US Hispanic patients (29.8% vs. 7.9%, P = 0.012); IDH2 mutations drove this difference. Post-progression survival was significantly shorter in patients from Mexico than US (3.0 vs. 11.4 months; P < 0.001), while OS remained similar.

CONCLUSIONS

IDH2 mutations are more prevalent in Mexican Hispanic individuals compared to US individuals and may be a crucial contributor to the previously reported survival benefit of Hispanic individuals in large population databases. These findings are critical for both screening of IDH2 mutations and targeted interventions in GBM.

Safety of radiosurgery concurrent with systemic therapy (chemotherapy, targeted therapy, and/or immunotherapy) in brain metastases: a systematic review

Stereotactic radiosurgery (SRS) is a standard option for brain metastases (BM). There is lack of consensus when patients have a systemic treatment, if a washout is necessary. The aim of this review is to analyze the toxicity of SRS when it is concurrent with chemotherapies, immunotherapy, and/or targeted therapies. From Medline and Embase databases, we searched for English literature published up to April 2020 according to the PRISMA guidelines, using for key words the list of the main systemic therapies currently in use And "radiosurgery," "SRS," "GKRS," "Gamma Knife," "toxicity," "ARE," "radiation necrosis," "safety," "brain metastases." Studies reporting safety or toxicity with SRS concurrent with systemic treatment for BM were included. Of 852 abstracts recorded, 77 were included. The main cancers were melanoma, lung, breast, and renal carcinoma. These studies cumulate 6384 patients. The median SRS dose prescription was 20 Gy [12-30] .For some, they compared a concurrent arm with a non-concurrent or a SRS-alone arm. There were no skin toxicities, no clearly increased rate of bleeding, or radiation necrosis with significant clinical impact. SRS combined with systemic therapy appears to be safe, allowing the continuation of treatment when brain SRS is considered.

The role of RB1 alteration and 4q12 amplification in IDH-WT glioblastoma

BACKGROUND

Recent studies have identified that glioblastoma IDH-wildtype (GBM IDH-WT) might be comprised of molecular subgroups with distinct prognoses. Therefore, we investigated the correlation between genetic alterations and survival in 282 GBM IDH-WT patients, to identify subgroups with distinct outcomes.

METHODS

We reviewed characteristics of GBM IDH-WT (2009-2019) patients analyzed by next-generation sequencing interrogating 205 genes and 26 rearrangements. Progression-free survival (PFS) and overall survival (OS) were evaluated with the log-rank test and Cox regression models. We validated our results utilizing data from cBioPortal (MSK-IMPACT dataset).

RESULTS

Multivariable analysis of GBM IDH-WT revealed that treatment with chemoradiation and RB1-mutant status correlated with improved PFS (hazard ratio [HR] 0.25, P < .001 and HR 0.47, P = .002) and OS (HR 0.24, P < .001 and HR 0.49, P = .016). In addition, younger age (<55 years) was associated with improved OS. Karnofsky performance status less than 80 (HR 1.44, P = .024) and KDR amplification (HR 2.51, P = .008) were predictors of worse OS. KDR-amplified patients harbored coexisting PDGFRA and KIT amplification (P < .001) and TP53 mutations (P = .04). RB1-mutant patients had less frequent CDKN2A/B and EGFR alterations (P < .001). Conversely, RB1-mutant patients had more frequent TP53 (P < .001) and SETD2 (P = .006) mutations. Analysis of the MSK-IMPACT dataset (n = 551) validated the association between RB1 mutations and improved PFS (11.0 vs 8.7 months, P = .009) and OS (34.7 vs 21.7 months, P = .016).

CONCLUSIONS

RB1-mutant GBM IDH-WT is a molecular subgroup with improved PFS and OS. Meanwhile, 4q12 amplification (KDR/PDGFRA/KIT) denoted patients with worse OS. Identifying subgroups of GBM IDH-WT with distinct survival is important for optimal clinical trial design, incorporation of targeted therapies, and personalized neuro-oncological care.

Research progress on radiotherapy technology and dose fraction scheme for advanced gliomas

Glioma is the most common central malignant tumor. High-grade glioma (HGG) has high malignancy and a short median survival. Complete surgical resection and comprehensive treatment with postoperative radiotherapy and chemotherapy is the recommended treatment for HGGs at present in clinic. Postoperative radiotherapy can reduce the local recurrence rate and prolong the survival time of patients. In recent years, researchers have made some progress on different radiotherapy technologies and dose fraction schemes. With the continuous development of medical technology, different groups of people should choose different dose fraction schemes, in order to realize the individualization of treatment schemes, and provide more benefits to patients. At present, the optimal radiotherapy dose, the fraction model, and how to achieve individualized radiotherapy remains unclear. In view of the poor prognosis of this disease, patients should be encouraged to participate in properly conducted experimental studies.

Radiosurgery for Glioblastoma

Glioblastoma (GBM) is infiltrative neoplasm with limited treatment options and poor overall survival. Stereotactic radiosurgery (SRS) allows spatially precise and conformal delivery of high doses of radiation. Salvage SRS for locally recurrent GBM was shown to improve patient survival and have more favorable safety profile than repeated surgical resection. Boost SRS after fractionated radiation therapy is sometimes attempted; however, Radiation Therapy Oncology Group 93-05 randomized clinical trial did not demonstrate benefits of upfront SRS that was administered before fractionated radiation. Administration of bevacizumab with SRS is associated with improved survival and can allow SRS dose escalation.

Landscape of Genomic Alterations in IDH Wild-Type Glioblastoma Identifies PI3K as a Favorable Prognostic Factor

PURPOSE

IDH wild-type (WT) glioblastoma (GBM) is an aggressive tumor with poor survival despite current therapies. The aim of this study was to characterize its genomic profile and determine whether a particular molecular signature is associated with improved survival outcomes.

PATIENTS AND METHODS

Tumor samples from 232 patients with IDH-WT GBM were sequenced, and the landscape of genomic alterations was fully delineated. Genomics data from The Cancer Genome Atlas (TCGA) cohort were analyzed for confirmation. Association of alterations with survival was evaluated in both univariable and multivariable approaches.

RESULTS

The genomic landscape of IDH-WT GBM revealed a high frequency of CDKN2A/B loss, TERT promoter mutations, PTEN loss, EGFR alteration, and TP53 mutations. Novel variants or gene mutations, such as ARID1B and MLL2, were identified. To better understand synergistic effects and facilitate decision making for precision medicine, we identified 11 pairs of gene alterations that tended to co-occur or were mutually exclusive, which were confirmed in the TCGA cohort. Survival analysis showed that genomic alterations in TP53 were associated with worse overall survival (OS). However, alterations in PI3K class I genes were associated with significantly better OS (univariable analysis: P = .002; multivariable analysis: hazard ratio [HR], 0.5785; P = .00162) and longer progression-free survival (univariable analysis: P = .0043; multivariable analysis: HR, 0.6228; P = .00913).

CONCLUSION

Genomic alterations in PI3K class I are a favorable prognostic factor in IDH-WT GBM. This new prognostic biomarker may facilitate risk stratification of patients, assist in clinical trial enrollment, and provide potential therapeutic targets

Radiobiology of stereotactic ablative radiotherapy (SABR): perspectives of clinical oncologists

Stereotactic ablative radiotherapy (SABR) is a novel radiation treatment method that delivers an intense dose of radiation to the treatment targets with high accuracy. The excellent local control and tolerance profile of SABR have made it become an important modality in cancer treatment. The radiobiology of SABR is a key factor in understanding and further optimizing the benefits of SABR. In this review, we have addressed several issues in the radiobiology of SABR from the perspective of clinical oncologists. The appropriateness of the linear-quadratic (LQ) model for SABR is controversial based on preclinical data, but it is a reliable tool from the perspective of clinical application because the biological effective dose (BED) calculated with it can represent the tumor control probability (TCP). Hypoxia is a common phenomenon in SABR in spite of the relatively small tumor size and has a negative effect on the efficacy of SABR. Preliminary studies indicate that a hypoxic radiosensitizer combined with SABR may be a feasible strategy, but so far there is not adequate evidence to support its application in routine practice. The vascular change of endothelial apoptosis and blood perfusion reduction in SABR may enhance the response of tumor cells to radiation. Combination of SABR with anti-angiogenesis therapy has shown promising efficacy and good tolerance in advanced cancers. SABR is more powerful in enhancing antitumor immunity and works better with immune checkpoint inhibitors (ICIs) than conventional fractionation radiotherapy. Combination of SABR with ICIs has become a practical option for cancer patients with metastases.