Selection of chemotherapy for glioblastoma expressing O(6)-methylguanine-DNA methyltransferase

Personalised therapeutic approaches to glioblastoma: A systematic review

Introduction

Glioblastoma is the most common and malignant primary brain tumour with median survival of 14.6 months. Personalised medicine aims to improve survival by targeting individualised patient characteristics. However, a major limitation has been application of targeted therapies in a non-personalised manner without biomarker enrichment. This has risked therapies being discounted without fair and rigorous evaluation. The objective was therefore to synthesise the current evidence on survival efficacy of personalised therapies in glioblastoma.

Methods

Studies reporting a survival outcome in human adults with supratentorial glioblastoma were eligible. PRISMA guidelines were followed. MEDLINE, Embase, Scopus, Web of Science and the Cochrane Library were searched to 5th May 2022. Clinicaltrials.gov was searched to 25th May 2022. Reference lists were hand-searched. Duplicate title/abstract screening, data extraction and risk of bias assessments were conducted. A quantitative synthesis is presented.

Results

A total of 102 trials were included: 16 were randomised and 41 studied newly diagnosed patients. Of 5,527 included patients, 59.4% were male and mean age was 53.7 years. More than 20 types of personalised therapy were included: targeted molecular therapies were the most studied (33.3%, 34/102), followed by autologous dendritic cell vaccines (32.4%, 33/102) and autologous tumour vaccines (10.8%, 11/102). There was no consistent evidence for survival efficacy of any personalised therapy.

Conclusion

Personalised glioblastoma therapies remain of unproven survival benefit. Evidence is inconsistent with high risk of bias. Nonetheless, encouraging results in some trials provide reason for optimism. Future focus should address target-enriched trials, combination therapies, longitudinal biomarker monitoring and standardised reporting.

Cytotoxic synergy between alisertib and carboplatin versus alisertib and irinotecan are inversely dependent on MGMT levels in glioblastoma cells

INTRODUCTION

Glioblastoma remains difficult to treat and patients whose tumors express high levels of O⁶-methylguanine DNA methyltransferase (MGMT) usually respond poorly to standard temozolomide chemotherapy. We have previously shown that the selective AURKA inhibitor alisertib potently inhibits growth of glioblastoma cells.

METHODS

We used colony formation assays, annexin V binding, and western blotting to examine the effects of alisertib on the antiproliferative capabilities of carboplatin and irinotecan in glioblastoma cells.

RESULTS

In colony formation assays, alisertib potentiated the antiproliferative effects of both carboplatin and irinotecan, often synergistically, including against glioblastoma tumor stem-like cells, as demonstrated by Chou-Talalay and Bliss statistical analyses. Western blotting showed that high MGMT expression in cell lines correlated with more pronounced potentiation of carboplatin's growth inhibitory effects by alisertib, while low MGMT expression correlated with stronger potentiation of irinotecan by alisertib. This pattern was also observed when these drug combinations were tested for their ability to induce apoptosis via annexin V binding assays. MGMT knockdown increased apoptosis caused by combined alisertib and irinotecan, while exogenous MGMT overexpression increased apoptosis from alisertib and carboplatin combination treatment.

CONCLUSIONS

These results suggest that tumor MGMT expression levels may be predictive of patient response to these drug combinations, and importantly that the combination of alisertib and carboplatin may be selectively effective in glioblastoma patients with high tumor MGMT who are resistant to standard therapy. Since clinical experience with alisertib, carboplatin and irinotecan as single agents already exists, these findings may provide rationale for the design of clinical trials for their use in combination treatment regimens.

Glioblastoma multiforme: Molecular characterization and current treatment strategy (Review)

Glioblastoma multiforme (GBM) is the most common and lethal malignant primary brain tumor. It is classified by the World Health Organization (WHO) in the group of diffusely infiltrating astrocytomas, representing up to 50% of all primary brain gliomas, and carries the poorest prognosis. Aberrant genetic events and signaling pathways have clearly demonstrated that GBM is highly anaplastic and a morphologically highly heterogeneous tumor. Understanding the genetic alterations, specific molecular biomarkers and proliferative pathways may promote therapeutic development for the management of GBM. Age, Karnofsky performance score, histology, position and the extent of tumor resection have been identified as potential prognostic factors for patients with GBM. In this study, we review the molecular characterization of tumor cells, the current standard of care for patients diagnosed with GBM, including gross or near-total resection of the tumor, followed by radiotherapy, stereotactic brachytherapy, chemotherapy and new targeted therapies. Thus, we conclude that multimodal approaches for the treatment of patients with GBM may significantly improve their prognoses.