Heterogeneity of response to immune checkpoint blockade in hypermutated experimental gliomas

Area of Science:

• Oncology
• Immunology
• Radiology

Background:

• Malignant brain tumors like glioblastomas exhibit resistance to immune checkpoint blockade (ICB).
• Predicting ICB response and understanding resistance mechanisms are challenging due to a lack of biomarkers and limited tissue accessibility.

Purpose of the Study:

• Investigate ICB resistance mechanisms in experimental gliomas.
• Identify predictive biomarkers for ICB therapy response.
• Explore therapeutic strategies to overcome ICB resistance.

Main Methods:

• Utilized syngeneic hypermutated experimental gliomas to model resistance to anti-PD-1 and anti-CTLA-4 therapy.
• Employed serial magnetic resonance imaging (MRI) to develop a radiomic signature.
• Analyzed tumor microenvironment for immune cell populations and molecular interactions.

Main Results:

• Observed a dichotomy in ICB response and acquired immune heterogeneity between responder and non-responder tumors.
• Developed a radiomic signature capable of predicting tumor regression post-ICB therapy.
• Demonstrated that macrophage-driven resistance involves CD4 T cell suppression and T regulatory cell expansion via the PD-L1/PD-1/CD80 axis.

Conclusions:

• ICB resistance in gliomas is complex and heterogeneous, even in syngeneic models.
• A radiomic signature can predict response to ICB therapy.
• Targeting PD-L1-expressing tumor-associated macrophages presents a potential strategy to enhance ICB efficacy.