Pembrolizumab alters the tumor immune landscape in a patient with dMMR glioblastoma.

We confirmed with a treating neurologist in this case that the treatment received by the individual whose samples are studied was part of routine clinical care and not a clinical trial, as the patient was previously diagnosed with Lynch syndrome (a mismatch repair deficiency). The use of pembrolizumab is recommended for treatment of tumors with high mutational burden due to mismatch repair deficiency and is currently considered standard of care for these tumors. Additionally, though the intervention and outcome are detailed in the manuscript, the focus of the manuscript is on reporting changes observed in the immune microenvironment at different points in the clinical trajectory - a retrospective analysis performed after clinical care was complete.