A Space-Time Continuum for Immunotherapy Biomarkers in Gastroesophageal Cancer?

In an annotated series of gastroesophageal adenocarcinomas differences in PD-L1 expression and tumor mutation burden occur between both paired contemporaneous primary and metastatic biopsies and pre/posttreatment samples. This work has implications for optimizing patient selection, serial testing, need for mechanistic understanding, and may underlie variable responses to checkpoint inhibitors in gastroesophageal cancers.