Concurrent and adjuvant temozolomide-based chemoradiotherapy schedules for glioblastoma: Hypotheses based on two prospective phase II trials

Survival Analysis of Glioblastoma: A Scientometric Perspective

BACKGROUND

Glioblastoma is the most aggressive primary brain tumor and the outlook for patients is usually pessimistic. Numerous ongoing studies have focused on enhancing the survival rate of glioblastoma patients. This study aims to analyze the research trends surrounding glioblastoma survival and facilitate studying recent topics to provide insight into the perspective, research fields, and international collaborations.

METHODS

Data were collected from the Web of Science database documents published from 1980 to 2022 and analyzed using Citespace and Biblioshiny software. After analyzing the data, we visualized the co-occurrence and coauthorship networks.

RESULTS

Eighteen main clusters were formed by drawing a document cocitation network. The result indicates that prognostic biomarkers, treating field, T cell, radiomic feature, and 5-aminolevulinic acid were trending topics for researchers. The most active countries in this field are the United States, followed by China, Germany, and Italy, respectively.

CONCLUSIONS

Considering the significance of monitoring the studies in glioblastoma patients, the current research has shown promising results in stratifying patient survival as a valuable tool for prognosis and prediction and eventually guiding treatment decisions. Using the results of this study, glioblastoma researchers can identify their potential colleagues and research gaps in this field.

Glioblastoma: from volumetric analysis to molecular predictors

BACKGROUND

Despite decades of therapeutic and molecular refinements, the prognosis of patients with glioblastoma (GBM) still remains unfavorable. Integrative clinical studies allow a better understanding of the natural evolution of GBM. To assess independent predictors of overall survival (OS) and progression free survival (PFS) clinical, surgical, molecular and radiological variables were evaluated. A novel preoperative volumetric magnetic resonance imaging (MRI) index for tumor prognosis in GBM patients was investigated.

METHODS

A cohort of 195 cases of patients operated for newly GBM were analyzed. Extent of tumoral resection (EOR), tumor growth pattern, expressed by preoperative volumetric ΔT1-T2 MRI index, molecular markers such as O6-methylguanine-DNA methyltransferase (MGMT) methylation and isocitrate dehydrogenase 1/2 (IDH1/2) mutation, were analyzed. Analysis of survival was done using Cox-proportional hazard models.

RESULTS

The 1-, 2- years estimated OS and PFS rate for the whole population were 61% and 27%, 38% and 17%, respectively. A better survival rate, both in terms of survival and tumor progression, was observed in patient with higher EOR (p=0.000), younger age (p=0.000), MGMT methylation status (p=0.001) and lower preoperative ΔT1-T2 MRI index (p=0.004). Regarding the tumor growth pattern a cut-off value of 0.75 was found to discriminate patient with different prognosis. Patients with a preoperative ΔT1-T2 MRI index <0.75 had a 1-year estimated OS of 67%, otherwise patients with a preoperative ΔT1-T2 MRI index >0.75 hada 1-year estimated OS of 34%.

CONCLUSIONS

In this investigation longer survival is associated with younger age, EOR, promoter methylation of MGMT and preoperative tumor volumetric features expressed by ΔT1-T2 MRI index. The preoperative ΔT1-T2 MRI index could be a promising prognostic factor potentially useful in GBM management. Future investigations based on multiparametric MRI data and next generation sequences analysis, may better clarify this result.

Temozolomide during radiotherapy of glioblastoma multiforme : Daily administration improves survival

BACKGROUND

Temozolomide-(TMZ)-based chemoradiotherapy defines the current gold standard for the treatment of newly diagnosed glioblastoma. Data regarding the influence of TMZ dose density during chemoradiotherapy are currently not available. We retrospectively compared outcomes in patients receiving no TMZ, TMZ during radiotherapy on radiotherapy days only, and TMZ constantly 7 days a week.

PATIENTS AND METHODS

From 2002-2012, a total of 432 patients with newly diagnosed glioblastoma received radiotherapy in our department: 118 patients had radiotherapy alone, 210 had chemoradiotherapy with TMZ (75 mg/m²) daily (7/7), and 104 with TMZ only on radiotherapy days (5/7). Radiotherapy was applied to a total dose of 60 Gy.

RESULTS

Median survival after radiotherapy alone was 9.1 months, compared to 12.6 months with 5/7-TMZ and to 15.7 months with 7/7-TMZ. The 1‑year survival rates were 33, 52, and 64%, respectively. Kaplan-Meier analysis showed a significant improvement of TMZ-7/7 vs. 5/7 (p = 0.01 by the log-rank test), while 5/7-TMZ was still superior to no TMZ at all (p = 0.02). Multivariate Cox regression showed a significant influence of TMZ regimen (p = 0.009) on hazard rate (+58% between groups) even in the presence of confounding factors age, sex, resection status, and radiotherapy dose concept.

CONCLUSION

Our results confirm the findings of the EORTC/NCIC trial. It seems that also a reduced TMZ scheme can at first prolong the survival of glioblastoma patients, but not as much as the daily administration.

A prospective study on neurocognitive effects after primary radiotherapy in high-grade glioma patients

BACKGROUND

Neurocognition is a very important aspect of a brain tumor patient's quality of life following radiotherapy. The aim of the present study was to assess neurocognitive functions of patients diagnosed with high-grade gliomas undergoing radiotherapy by using the NeuroCogFx(®) test and to examine relevant dose/volume parameters as well as patient characteristics potentially influencing the neurological baseline status and subsequent outcome.

METHODS

The cohort consisted of 44 astrocytoma World Health Organization grade III/IV patients. The NeuroCogFx(®) test was carried out on patients during (N = 44) and after (N = 21) irradiation. The test examines verbal/figural/short-term/working memory, psychomotorical speed, selective attention and verbal speed. The results were compared with regular patient and treatment data with an emphasis on the dose applied to the hippocampus.

RESULTS

Overall there were only slight changes in the median test results when comparing the baseline to the follow-up tests. In the 'verbal memory test' lower percentile ranks were achieved in left-sided tumors compared to right-sided tumors (p = 0.034). Dexamethasone intake during radiotherapy was significantly correlated with the difference between the two test batteries. Concerning figural memory, a correlation was detected between decreased figural recognition and the radiation dose to the left hippocampus (p = 0.045).

CONCLUSION

We conclude that tumor infiltration of the hippocampus has an impact on neurocognitive function. However, treatment with radiotherapy seems to have less influence on cognitive outcome than expected.

Radiotherapy of spinal cord gliomas : A retrospective mono-institutional analysis

BACKGROUND

Due to the rarity of spinal cord gliomas, no consensus has been reached regarding the optimal treatment strategy. The aim of the present retrospective study was to identify patient and tumor characteristics and to evaluate the effectiveness of radiotherapy within this setting.

PATIENTS AND METHODS

Patients diagnosed with spinal cord gliomas between 2003 and 2013 and treated at the Department of Radiation Oncology, University of Munich, were retrospectively analyzed. Overall survival was estimated with the Kaplan-Meier method and univariate analysis was performed by log-rank testing.

RESULTS

A total of 16 patients were identified. The cohort consisted of seven primary spinal cord gliomas and eight cases of metastases of cerebral gliomas. Median follow-up was 42 months and median total radiation dose was 45.0 Gy. In all, 62.5 % of patients received a simultaneous chemotherapy with temozolomide. The median overall survival was 6 months (95% CI: 0-27.5 months). Surgical resection of the tumor was a significant predictor of improved survival, compared with radiotherapy alone (p = 0.001). Patients with the diagnosis of a primary spinal cord glioma survived significantly longer than those presenting with a metastatic deposit from a cerebral glioma (p < 0.001). A statistically significant dose-response relationship at dose levels of ≥ 45 Gy vs. < 45 Gy could be derived (p < 0.001). Simultaneous chemotherapy did not influence survival outcome.

CONCLUSION

Despite the aggressive treatment in the present study, the prognosis for spinal cord gliomas was still poor, with a median overall survival of 6 months. To the best of our knowledge, this is the largest study reporting the results of simultaneous chemoradiation in spinal cord gliomas. A combined chemoradiation treatment seems feasible and can be considered as a new treatment option in the management of spinal cord gliomas.

Recent advances in targeted therapy for glioblastoma

Glioblastomas are the most common form of brain tumor with a very dismal prognosis. While a standard treatment regimen of surgery followed by chemo/radiotherapy is currently used, this has only marginally improved the survival time of patients with little benefit on tumor recurrence. Although many molecular targets have already been identified and tested in clinical trials, very few are approved for use in clinics. Efforts are ongoing to target newer molecules that could be used for drug development. This review provides up-to-date information on the drugs and their molecular targets, which are currently in different stages of clinical trials. Since multiple signaling pathways are deregulated, it appears that the use of combination drugs along with personalized targeting approach would provide better therapy in the future.

Hippocampal EUD in primarily irradiated glioblastoma patients

BACKGROUND

Radiation delivery for malignant brain tumors is gradually becoming more precise. Particularly the possibilities of sparing adjacent normal structures such as the hippocampus are increasing. To determine its radiation exposure more exactly, the equivalent uniform dose (EUD) of the hippocampus was compared with further treatment parameters. This way sparing options could be found.

METHODS

From the database of the University hospital of Munich 61 glioblastoma patients were selected who received primary radiotherapy in 2011. General data about the etiology, treatment course, survival of the patients and dose parameters were retrieved.

RESULTS

In a linear regression analysis the side of the tumor (left hippocampus: p < 0.001/right hippocampus: p = 0.009) and its temporal location (left hippocampus: p = 0.015/right hippocampus: p = 0.033) were identified as factors with a significant influence on the EUD of the respective hippocampus. Besides this, the size of the planning target volume (PTV) and the EUD of the hippocampus correlated significantly (p = 0.027; Pearson correlation = 0.291). The median PTV size of the tumor in the right hemisphere was 386.1 ml (range 131.2-910.7 ml), and in the left hemisphere 291.3 ml (range 146.0-588.9 ml) (Kruskal-Wallis test: p = 0.048). A dose quartile analysis showed that 31 patients had a high dose exposure of the hippocampus on one side while having a moderate dose exposure in the other side.

CONCLUSIONS

The radiation exposure of the respective hippocampus is dependent on the side where the tumor is located as well as on whether it is temporally located. The exposure of the contralateral hippocampus is further dependent on multiple additional factors - nevertheless a reasonable protection seems to be possible in about half of all cases.

Current and investigational drug strategies for glioblastoma

Medical treatments for glioblastoma face several challenges. Lipophilic alkylators remain the mainstay of treatment, emphasising the primacy of good blood-brain barrier penetration. Temozolomide has emerged as a major contributor to improved patient survival. The roles of procarbazine and vincristine in the procarbazine, lomustine and vincristine (PCV) schedule have attracted scrutiny and several lines of evidence now support the use of lomustine as effective single-agent therapy. Bevacizumab has had a convoluted development history, but clearly now has no major role in first-line treatment, and may even be detrimental to quality of life in this setting. In later disease, clinically meaningful benefits are achievable in some patients, but more impressively the combination of bevacizumab and lomustine shows early promise. Over the last decade, investigational strategies in glioblastoma have largely subscribed to the targeted kinase inhibitor paradigm and have mostly failed. Low prevalence dominant driver lesions such as the FGFR-TACC fusion may represent a niche role for this agent class. Immunological, metabolic and radiosensitising approaches are being pursued and offer more generalised efficacy. Finally, trial design is a crucial consideration. Progress in clinical glioblastoma research would be greatly facilitated by improved methodologies incorporating: (i) routine pharmacokinetic and pharmacodynamic assessments by preoperative dosing; and (ii) multi-stage, multi-arm protocols incorporating new therapy approaches and high-resolution biology in order to guide necessary improvements in science.