P04.05 “The Development Tumor Model” used to reproduce and follow glioblastoma evolution in the whole brain and to test and monitor novel therapies

Abstract

Background

"The development tumor model" (TDTM) is currently the only preclinical animal model which can replicate the entire glioblastoma natural history both in the bulk and in the micro-infiltrated brain parenchyma. Furthermore, the model is perfectly suited to test new therapies and continuously monitor subclonal emerging populations after treatment in order to identify molecular predictors of response to innovative therapies.

Material and Methods

TDTM is a xenogeneic orthotopic transplantation model using glioblastoma-derived cell lines from the pre-hypoxic phase of the founding clone (or of the more ancestral one, inferred after reconstruction of the phylogenetic tree) cultivated in a neurobasal serum-free medium as transplanted material. The model posits the transplantation of the same number of cells into several genetically identical immunocompromised rodents (an inbred strain of mice or rats) at the same time (time zero). Thus, the model creates a pool of twin immunodeficient transplant animals examined under the same conditions. By sacrificing one animal a week (or choosing others intervals as needed) and performing multiple biopsies (from the bulk, ipsilateral hemisphere, corpus callosum, contralateral hemisphere) and stainings on sections during xenograft progression, we can biologically and spatiotemporally (i.e geographically and longitudinally) reproduce and monitor both the entire evolution in the bulk (appreciating the evolving variegated clonal architecture and increasingly more complex intratumor heterogeneity) and the detection of all steps (from the beginning to the end of the natural history) of the brain parenchyma micro-infiltration.

Results

TDTM can allow us to identify the CSCs in the brain parenchyma shedding light on the perivascular parenchymal niche where founder CSCs settle quiescent in G₀ state until activation. Furthermore, TDTM can enable us to test new therapies. By delivering to all rodents at the same time the identical dose and modality of therapeutic treatments over xenograft progression, the model allows us to follow the dynamics, response and emergence of subclones both in the bulk and in the micro-infiltrated brain parenchyma that occur during and after innovative therapies either as chemotherapy, radiotherapy, immunotherapy or others.

Conclusion

TDTM is a very powerful tool to follow the entire glioblastoma evolution and identify appropriate CSC targets. Indeed, glioblastoma progression can be monitored over time as if it were occurring in a single animal both in the bulk and, most importantly, in the micro-infiltrated brain parenchyma. Furthermore, the model is perfectly suitable to test and monitor innovative, targeted and personalized therapies to overcome the two causes of resistance.