A new study published in Nature Communications, shows that immune cells in the cerebrospinal fluid could constitute novel biomarkers of the response to immune-based therapy. The researchers from the Vall D’Hebron Institute of Oncology found that profiling these cells enables the characterization of the brain metastasis microenvironment.
"One of the major challenges in improving outcomes for patients suffering from brain metastases caused by these cancers is that new lesions can differ immensely from the primary tumor, and thus respond in a different way to immune-based therapies," observes Joan Seoane, co-corresponding author.
Results from previous studies led by Seoane, as well as those of other groups, have evidenced that cerebrospinal fluid can provide vital insights into the genomic characteristics of brain tumors and therefore be used as a minimally invasive liquid biopsy. Spurred by these findings, the investigators conducted this present research to establish whether they could effectively characterize the immunological phenotype through the analysis of cerebrospinal fluid.
To test this hypothesis, the team analyzed samples from 48 patients with brain metastasis. They then assessed the immune cells present in the brain metastases, and in parallel, performed immune cell profiling of the cerebrospinal fluid. They sought to identify which cell types were present in the cerebrospinal fluid and compare them with those obtained from the metastatic lesions.
By analyzing cerebrospinal fluid, the researchers were able to identify the T-cells that recognize the tumor, and those that are active in treatment. "Each immune T-cell has a unique sequence that recognizes a particular tumor antigen. When their tracing and targeting commence, these cells are activated and begin to proliferate. Through this study, we have been able to characterize the individual sequences of immune cells and, in this way, identify which immune cells are fighting the tumor and discern how they evolve over time," concludes Seoane.