Syngeneic Mouse Model Of Glioblastoma

01 / 22 / 2016

To assess the in vivo efficacy and mechanism of action of novel therapeutic strategies for brain cancer, Explicyte has validated a syngeneic mouse tumor model of glioma, which closely mimics human glioblastoma (GBM) in terms of tumor progression and immune response. A key advantage of this model, based on the GL261-Luc2 murine glioma cell line, relies on the possibility of quantifying tumor growth in live animals by bioluminescence imaging along the study.

A Relevant In Vivo Model Of Glioblastoma For Preclinical Testing

  • Intracranial tumor development: GL261-Luc2 murine glioma cells are stereotactically implanted in mice brain by  surgery. Tumor growth then mimics major features of human glioblastoma, including immune cell activation & infiltration, microvascular proliferation, astrogliosis …
  • Tumor-host immune interactions: tumor cells are implanted into immunocompetent mice, thus allowing to assess the ability of drug candidates to activate or restore the anti-cancer immune response.
  • Validated gold standard chemotherapy and immune checkpoint inhibitors: To assess novel combination regimens, treatment protocols have been validated and optimized for Temozolomide and cancer immunotherapies (anti-CTLA-4 and anti-PD-L1 monoclonal antibodies). In vivo efficacy and immune response profiles have been characterized.

Test compound A synergizes with anti-PDL1 in a GL261-Luc2 glioblastoma tumor model. Mice were intracranially implanted with GL261-Luc2 tumor cells, and exposed to anti-PD-L1 antibody alone and in compination witn drug candidate A. Tumor growth was followed over time and determined by bioimaging. This experimental session demonstrated that combination of anti-PDL1 with A promotes in some mice full tumor rejection.

In Vivo Study Of Anticancer Efficacy

  • In vivo imaging of tumor growth: GL261-Luc2 glioma cells stably express 2ndgeneration firefly luciferase, thus allowing quantitative measurements of tumor progression along the experimental session.
  • Standard efficacy package: Experimental groups (N=8-10) are closely monitored  for body weight and survival and tumor size assessed weekly by bioluminescence imaging .
  • Weekly progress reports enable to closely monitor the efficacy profile of compounds and possibly adjust the experimental protocol.

Effect of Temozolomide and Immune checkpoint inhibitors on tumor growth (bioluminescence imaging) and survival of GL261-Luc2 (glioblastoma) tumor bearing mice. Mice were implanted with GL261-Luc2 tumor cells, and exposed either to Temozolomide (TMZ), or anti-CTLA4 antibody. Tumor growth was followed over time and determined by in vivo bioimaging.

In Vivo Mechanism Of Action : Immune Response Profiling

  • Satellite mice can be included in each experimental group to evaluate impact of treatment exposure on tumour–host immune interactions at the tumor site and also in peripheral compartments (blood, spleen, lymph nodes).
  • Blood samples can also be collected regularly to determine serological profiles of responding or non-responding subgroups – this approach avoiding to re-launch a whole experimental session.
  • Immune biomarker analysis: key immunological markers (eg. CD4, CD8, FoxP3, CD11b, Gr1, …) can be tracked using quantitative and multiplex technologies, such as flow cytometry and RT-qPCR.

Example of immune profiling using FACS. Immune cell profiling and detection of MDSC (CD11b+/Gr1High) and FoxP3+ immune cells by flow cytometry within intracerebral glioblastoma. These results show the presence of immune suppressive cells with a majority of FoxP3+ cells being CD4 negative.