Development of Molecularly Targeted Agents and Immunotherapies in Glioblastoma: A Personalized Approach

Expression, prognostic significance and therapeutic implications of PD-L1 in gliomas

The advent of checkpoint immunotherapy, particularly with programmed death‐1 (PD‐1) and programmed death‐ligand 1 (PD‐L1) inhibitors, has provided ground‐breaking results in several advanced cancers. Substantial efforts are being made to extend these promising therapies to other refractory cancers such as gliomas, especially glioblastoma, which represents the most frequent and malignant glioma and carries an exceptionally grim prognosis. Thus, there is a need for new therapeutic strategies with related biomarkers. Gliomas have a profoundly immunosuppressive tumour micro‐environment and evade immunological destruction by several mechanisms, one being the expression of inhibitory immune checkpoint molecules such as PD‐L1. PD‐L1 is recognised as an important therapeutic target and its expression has been shown to hold prognostic value in different cancers. Several clinical trials have been launched and some already completed, but PD‐1/PD‐L1 inhibitors have yet to show convincing clinical efficacy in gliomas. Part of the explanation may reside in the vast molecular heterogeneity of gliomas and a complex interplay within the tumour micro‐environment. In parallel, critical knowledge about PD‐L1 expression is beginning to accumulate including knowledge on expression levels, testing methodology, co‐expression with other checkpoint molecules and prognostic and predictive value. This article reviews these aspects and points out areas where biomarker research is needed to develop more successful checkpoint‐related therapeutic strategies in gliomas.

NVP-BEZ235 or JAKi Treatment leads to decreased survival of examined GBM and BBC cells

Cancer cells almost universally harbor constitutively active Phosphatidylinositol-3 Kinase (PI3K) Pathway activity via mutation of key signaling components and/or epigenetic mechanisms. Scores of PI3K Pathway inhibitors are currently under investigation as putative chemotherapeutics. However, feedback and stem cell mechanisms induced by PI3K Pathway inhibition can lead to reduced treatment efficacy. To address therapeutic barriers, we examined whether JAKi would reduce stem gene expression in a setting of PI3K Pathway inhibition in order to improve treatment efficacy. We targeted the PI3K Pathway with NVP-BEZ235 (dual PI3K and mTOR inhibitor) in combination with the Janus Kinase inhibitor JAKi in glioblastoma (GBM) and basal-like breast cancer (BBC) cell lines. We examined growth, gene expression, and apoptosis in cells treated with NVP-BEZ235 and/or JAKi. Growth and recovery assays showed no significant impact of dual treatment with NVP-BEZ235/JAKi compared to NVP-BEZ235 treatment alone. Gene expression and flow cytometry revealed that single and dual treatments induced apoptosis. Stem gene expression was retained in dual NVP-BEZ235/JAKi treatment samples. Future in vivo studies may give further insight into the impact of combined NVP-BEZ235/JAKi treatment in GBM and BBC.