LAG3 and glioblastoma: For example, pembrolizumab in a hypermutant tumor early after resection increased the abundance of numerous cytokines and chemokines,58 including LAG-3, which is currently under clinical evaluation in GBM in combination with pembrolizumab, highlighting the potential to identify emerging resistance mechanisms through CSF analysis.59 Of note, LAG-3 increased months after surgery, indicating that resection-associated temporal CSF changes should be considered when assessing PD impact.