Nat Commun: Immune cell analysis of cerebrospinal fluid can characterize the microenvironment of brain metastases

Brain metastases (BrM) are the most common tumors in the brain and are a devastating cancer complication.
Previous studies have shown that immune checkpoint inhibitors (ICIs, such as anti-PD1, anti-PD-L1, anti-CTLA4, etc.
) have shown significant clinical benefits in patients with progressive or metastatic solid tumors.
However, only a small percentage of patients respond to ICI treatment.

The degree and phenotype of immune cell infiltration have been used to predict the response to ICI.
However, obtaining samples from brain malignant tumors is challenging, and the anatomical location of brain tumors and related surgical risks also limit the characterization of related immunophenotypes.

In order to comprehensively map the immune cell maps of BrM and the corresponding cerebrospinal fluid (CSF), in this study, the researchers used single-cell RNA sequencing combined with T cell receptor genotyping to characterize brain lesions and CSF.
Immune Cells.
Researchers found that tumor immune infiltration, especially CD8+ T cell infiltration, can be distinguished by analysis of cerebrospinal fluid to predict the verification status of ICI response.
Similarly, the same clonal T-cell receptors were detected in brain lesions and CSF samples, confirming that there was a cell exchange between these compartments.

Identification of tumor immune infiltration patterns in brain metastases

All in all, the results of the study revealed that CSF immune cell analysis can provide a non-invasive alternative to predict patient response to ICI and determine the presence of clonal T cell receptors in brain metastases.

Original source:

Rubio-Perez, C.
, Planas-Rigol, E.
, Trincado, JL et al.