ARG1 and Epstein-Barr virus infection: IDO1-high, ARG1-high, and particularly both high cases were significantly enriched in the PX3 group, while other parameters that may have predictive values for responders of immunotherapy, such as mutation numbers (MSI-high), EBV infection, and intratumoral tumor-infiltration lymphocytes (IT-TILs), failed to stratify patients into the three subtypes (Fig. 6c).