Mutational profile and HLA tumor cell expression before pembrolizumab treatment and at disease relapse following an initial CR in a participant with DLBCL. (A) Comparison of the tumor mutational profile of a DLBCL tumor before pembrolizumab and at the time of relapse after a 1-year CR. (B) Line plot demonstrating changes in variant allele frequency of lymphoma driver mutations before pembrolizumab treatment and at the time of acquired resistance to pembrolizumab. (C) Multiparameter immunofluorescence staining revealing decreased HLA-I expression on Pax5⁺ tumor cells at the time of pembrolizumab relapse compared with baseline in the participant with DLBCL, with an acquired EZH2 mutation at disease progression. (D) Degree of tumor infiltration by CD4⁺ and CD8⁺ T cells at the time of pembrolizumab progression as assessed by IHC.