CHI3L1 contributes to an immune suppressed tumour microenvironment in highly invasive brain metastases
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ABSTRACT: Brain metastases (BrM) occur in up to 40% of cancer patients, causing nearly one-fifth of cancer deaths. While immune checkpoint inhibitors (ICIs) benefit some BrM patients, responses remain highly variable. This variability partly reflects distinct histopathological growth patterns that include minimally invasive (MI) and highly invasive (HI) brain BrM. Here we show that MI BrM exhibit robust immune infiltration, whereas HI lesions are immunosuppressed. However, histological differentiation between MI and HI can be challenging due to subjective margin assessment. Here, using highly multiplexed spatial proteomics on 119 tumour sections from 46 patients with BrM, we identify CHI3L1 as a key mediator of the immunosuppressive microenvironment in HI BrM. In preclinical models, genetic deletion of CHI3L1 converts immune-cold metastases into lymphocyte-rich, ICI-responsive lesions infiltrated by granzyme-B+ CD8+ T cells. In BrM patients treated with ICI, immunohistochemical quantification of CHI3L1 expression was a stronger predictor of ICI response than traditional MI/HI classification. Thus, CHI3L1 represents a promising biomarker and therapeutic target for BrM.
ORGANISM(S): Homo sapiens
PROVIDER: GSE303531 | GEO | 2026/03/13
REPOSITORIES: GEO
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