Personalising glioblastoma medicine: explant organoid applications, challenges and future perspectives

Abstract

Glioblastoma (GBM) is a highly aggressive adult brain cancer, characterised by poor prognosis and a dismal five-year survival rate. Despite significant knowledge gains in tumour biology, meaningful advances in patient survival remain elusive. The field of neuro-oncology faces many disease obstacles, one being the paucity of faithful models to advance preclinical research and guide personalised medicine approaches. Recent technological developments have permitted the maintenance, expansion and cryopreservation of GBM explant organoid (GBO) tissue. GBOs represent a translational leap forward and are currently the state-of-the-art in 3D in vitro culture system, retaining brain cancer heterogeneity, and transiently maintaining the immune infiltrate and tumour microenvironment (TME). Here, we provide a review of existing brain cancer organoid technologies, in vivo xenograft approaches, evaluate in-detail the key advantages and limitations of this rapidly emerging technology, and consider solutions to overcome these difficulties. GBOs currently hold significant promise, with the potential to emerge as the key translational tool to synergise and enhance next-generation omics efforts and guide personalised medicine approaches for brain cancer patients into the future.

Keywords: Brain cancer; Explants; Glioblastoma; Heterogeneity; Organoids; Patient-derived; Personalised medicine.

Fig. 1

The History of 3D Brain Tumour Model Development. A timeline illustrating the evolution of various 3D preclinical models in GBM (A). Models include: PDOs (B), genetically engineered models (C), co-culturing models (D), bio-printed organoids (E), organotypic slice cultures (F) and PDEs (G). Abbreviations: embryonic stem cell (ES cell), cerebral organoid glioma (GLICO), neoplastic cerebral organoids (neoCOR), human glioma stem cell (HGSC), mouse embryonic stem cell (MESC), glioma stem cell (GSC), human embryonic stem cell (HESC). Created with BioRender.com

Fig. 2

GBO drug assay approaches. Step 1: GBO model establishment - involves microdissection and processing of the tumour tissue, GBO generation and biobanking. Step 2: Patient model characterisation - constitutes of genomic and transcriptomic characterisation of tumour. Drug target and/or biomarker expression can be examined by IHC staining on tumour tissue. Studies in the matching, patient-derived cell line may also be performed to select candidate drugs to take forward for testing in the GBOs. Step 3: GBO drug assay preparation – includes GBO QC, which can be performed to select viable GBOs prior to drug treatment commencement. During treatment exposure, GBO size can be tracked as a measure of treatment efficacy via bright field microscopy. Step 4: GBO endpoint analysis – this constitutes of live-cell readouts prior to GBO dissociation for scRNA-seq or embedding and downstream analysis by techniques such as immunofluorescence microscopy and spatial RNA-seq. Abbreviations: Whole exome sequencing (WES), Immunohistochemistry (IHC), Quality control (QC), single nuclei (sn), single cell (sc). Created with BioRender.com

Fig. 3

The current pros and cons of GBOs. Advantages include the retention of GBM heterogeneity, an intact TME, the quick generation time and the ability to biobank GBOs, and the apparent correlation between responses in GBOs and patients. Limitations include insufficient amount and quality of resected tissue, the lack of vascularisation and blood circulation, the absence of standardised and automated workflows for GBO assays and the inability to replicate clinical treatments due to the limited lifespan of GBOs. Abbreviations: TME: tumour microenvironment. Created with BioRender.com