MLH1 and colorectal carcinoma: Considering all four patients are MSS based on the IHC data (nuclear expression of MLH1 (MutL homolog 1), MSH2 (MutS homolog 2), MSH6 (MutS homolog 6), and PMS2 (PMS1 homolog 2, mismatch repair system component)) (Supplementary Figure S3), a high level of PD-L1 (CD274) within specific TMEs may evoke a better immunogenic response and serve as a prognostic marker for immunotherapies for MSS CRC patients.