Table 1.

Comparison of the Advantages and Disadvantages of the Individual Models.

Model	Xenograft	Syngeneic	Humanized	Genetically engineered
Operation	Yes	Yes	Yes	No
Human cells	Yes	No	Yes	No
Longitudinal study	Yes	Yes	Yes	No
Immunosuppression	Yes	No	No	No
Graft vs. host reactions	Yes	No	No	No
Tumor microenvironment (human/mice)	Rodent	Rodent	Human (possible residual parts of the rodent)	Rodent
Suitable study design	•Longitudinal studies •Molecular studies(serum-free condition) •Potential for personalized  anticancer treatment •Clinical relevance •Biomarker studies •Stem cell studies  (serum-free condition)	•Longitudinal studies •Immune studies	•Patient-oriented investigations	•Molecular investigations •Studies that need an intact tumor microenvironment •Tumorigenesis studies
Limitations	•Restricted translation to humans •Immune studies  (immunodeficient rodents) •Tumorigenesis studies	•Restricted translation to humans •Non-human glioblastoma •Tumorigenesis studies	•Short time windows when examinations are to be carried out for specific patients •Tumorigenesis studies	•Translation to human biology restricted •Different molecular structure from human glioblastoma •Limited number of mutations •Longitudinal studies and (immune) therapeutic studies
References	(Lenting et al., 2017)	(Huszthy et al., 2012)	(Morton et al., 2016)	(Noorani, 2019)

The main general advantages and disadvantages of the orthotopic and xenograft approaches are additionally listed.