Immune niches in brain metastases contain TCF1+ stem-like T cells, are associated with disease control and are modulated by preoperative SRS

We analyzed immune infiltration in 67 brain metastasis (BrM) and found high frequencies of PD1+TCF1+stem-like CD8+T-cells and TCF1-effector-like cells. Overall design: CD45+ TILS and CD8+ TILS were mixed at a 1:1 ratio from patients with irradiated and unirradiated brain metastases were FACS-purified for every sample. Single-cell suspensions of FACS-purified cells were loaded onto the 10X Genomics Chromium Controller. Library construction was performed using the Chromium Single Cell 5' Library Construction Kit followed by sequencing on a HiSeq3000.