Table 1.

A comparison of different glioblastoma tumor models for studying immunotherapy.

Tumor Model	Description	Advantages	Disadvantages	References
In Vitro
Tumor cell lines	established tumor cell lines, grown as monolayers in serum-containing media	+rapid expansion +low costs +long tradition +easy genetic manipulation +well-characterized +simple	-clonal selection in cell cultures based on media selection -lack of clonal diversity and heterogeneity -lack of TME and ECM	[111]
Cancer stem cells	patient-derived tumor cells grown in serum-free and growth factor-supplemented media as tumorspheres	+reflect stem-like features and therapeutic resistance +preserve the tumor’s genetic background +phenotypic heterogeneity +3D model	-lack of TME and ECM -clonal selection	[112]
Cell co-cultures	2D or 3D co-cultures of tumor and non-tumor cells, such as immune cells and stromal cells	+heterotypic cellular interactions +simple +mechanistic studies of cellular cross-talk in TME	-lack of complex TME and architecture	[113]
Organotypic tissue slice cultures	precision-cut slices of tumor tissue, mounted onto porous membranes for mechanical support, and cultured in a controlled conditions	+recapitulate TME +preserve inter-intra-tumoral heterogeneity and heterotypic cellular interactions +clinically relevant therapeutic response +platform for studying the tumor immune cell environment +tumor cell invasion model system	-limited by the availability of fresh patient samples -short lifespan -cryopreservation method is not optimized -not adapted for high throughput analysis	[114,115]
Patient-derived organoids	3D in vitro tissue constructs composed of multiple cell types, patient-based from resected tumors	+preserve inter-intra-tumoral heterogeneity and heterotypic cellular interactions +preserve the tumor’s genetic background +recapitulate TME +pre-clinical applications +3D model +high through-put +clinically relevant therapeutic response +feasibility of co-culture with immune cells	-variable ability to maintain over very long periods -limited by the availability of fresh patient samples -limited immune component -lack of model optimization -do not recapitulate tumor initiation	[116,117]
Genetically- engineered cerebral organoids	3D in vitro tissue constructs created by using genetic manipulations to induce tumorigenesis in cerebral organoids	+3D model +good reproducibility +clinically relevant therapeutic response +enable to study early phases of tumorigenesis and tumor progression +brain tissue architecture	-poorly recapitulate TME -the tumor’s genetic background is not preserved -lack of immune component	[118,119]
In Vivo
Syngeneic mouse model	derived by transplanting mouse tumor cell lines or CSCs into strain-matched mice	+immune system and response +present TME +simple with a long tradition +allows genetic modifications +tumor cell heterogeneity and clonal diversity with implanted CSCs	-limited tumor cell heterogeneity and clonal diversity with implanted tumor cell line -high costs -laborious, time-consuming -lack of human tumor-immune cell interactions -TME is of rodent origin	[110,120]
Genetically engineered mouse tumor model	created by introducing genetic modifications that result in spontaneous tumor development	+allows genetic modifications +tumor cell heterogeneity and clonal diversity +tumor-immune cell interactions if immunocompetent mice are used +present TME	-large number of animals -laborious, time-consuming -poor inter-animal comparability -high costs -TME is of rodent origin	[121]
Patient-derived xenografts	derived by transplanting human tumor explants into immunodeficient mice	+tumor cell heterogeneity and clonal diversity +present TME +reflect tumors in human +little graft-versus-host rejection for adoptive cell therapy (CART) +preserve the tumor’s genetic background	-high costs -fail to develop a functional immune system -lack of human tumor-immune cell interactions -laborious, time-consuming -TME is of rodent origin	[90,122]
Humanized mouse tumor model	generated by the engraftment of human cancer cell lines or human PDX tumors into mice with a reconstituted human immune response	+tumor heterogeneity and clonal diversity +present TME +human immune cells +mimicking human tumor and immune system interactions +realistic representation of immunotherapy safety and clinical response +preserves the tumor’s genetic background	-long-lasting establishment -high costs -laborious, time-consuming -slow tumor growth	[110,123,124]

CSC: cancer stem cell; ECM: extracellular matrix; PDX: patient-derived xenografts; TME: tumor microenvironment.