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Updated: Jun 11, 2025
A Robust Discovery Platform for the Identification of Novel Mediators of Melanoma Metastasis
Published on: March 8, 2022
IMMUNE AND MOLECULAR CORRELATES OF RESPONSE TO IMMUNOTHERAPY REVEALED BY BRAIN-METASTATIC MELANOMA MODELS
Amélie Daugherty-Lopès1, Eva Pérez-Guijarro2, Vishaka Gopalan3
1Inflammatory Cell Dynamics Section, Laboratory of Integrative Cancer Immunology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
Abstract:
Despite the promising results of immune checkpoint blockade (ICB) therapy, outcomes for patients with brain metastasis (BrM) remain poor. Identifying resistance mechanisms has been hindered by limited access to patient samples and relevant preclinical models. Here, we developed two mouse melanoma BrM models that recapitulate the disparate responses to ICB seen in patients. We demonstrate that these models capture the cellular and molecular complexity of human disease and reveal key factors shaping the tumor microenvironment and influencing ICB response. BR1-responsive tumor cells express inflammatory programs that polarize microglia into reactive states, eliciting robust T cell recruitment. In contrast, BR3-resistant melanoma cells are enriched in neurological programs and exploit tolerance mechanisms to maintain microglia homeostasis and limit T cell infiltration. In humans, BR1 and BR3 expression signatures correlate positively or negatively with T cell infiltration and BrM patient outcomes, respectively. Our study provides clinically relevant models and uncovers mechanistic insights into BrM ICB responses, offering potential biomarkers and therapeutic targets to improve therapy efficacy.
Insights
New mouse models reveal why brain metastases resist immune checkpoint blockade therapy. Understanding these resistance mechanisms, involving microglia and T cells, can improve cancer treatment strategies.
Area of Science:
- Oncology
- Immunology
- Neuroscience
Background:
- Immune checkpoint blockade (ICB) therapy shows promise but has poor outcomes for brain metastasis (BrM).
- Limited patient samples and preclinical models hinder the identification of ICB resistance mechanisms in BrM.
- Developing relevant models is crucial for understanding BrM and improving ICB efficacy.
Purpose of the Study:
- To develop and characterize novel mouse melanoma BrM models that mimic patient responses to ICB.
- To investigate the cellular and molecular factors influencing ICB response in BrM.
- To identify potential biomarkers and therapeutic targets for improving BrM treatment.
Main Methods:
- Development of two distinct mouse melanoma BrM models.
- Analysis of tumor microenvironment, including microglia and T cell infiltration.
- Correlation of gene expression signatures (BR1 and BR3) with ICB response and patient outcomes.
Main Results:
- The models recapitulate disparate ICB responses observed in patients.
- BR1-responsive tumors promote inflammatory microglia and T cell recruitment.
- BR3-resistant tumors utilize neurological programs and tolerance to limit T cell infiltration.
- BR1 and BR3 expression signatures correlate with T cell infiltration and patient outcomes in humans.
Conclusions:
- Clinically relevant mouse models for BrM ICB research have been established.
- Mechanistic insights into BrM resistance to ICB, involving microglia-T cell interactions, were uncovered.
- BR1 and BR3 signatures may serve as biomarkers and potential therapeutic targets for improving ICB efficacy in BrM patients.
