Comparison of mutational landscape, genomic, and immune-related biomarkers with regard to degree of differentiation and primary localization. A and E-H, Comparative analysis of average somatic variants (A), MSI score (E), TMB (F), TNB (G), CD8⁺ TILs (H) in patients with NETs (n = 15) and NECs (n = 32) using unpaired t-test with Welch’s correction. Data represent mean ± SEM. **P < .01; B-D, Comparative analysis of TP53, RB1 mutation, and TP53/RB1 co-mutation frequency (B) and the ratio of cases with HLA LOH (C) or HLA-I homogeneity (D) in patients with NETs and NECs using Fisher exact test. I-L, Comparative analysis of TP53 (I), RB1 (J) mutation frequency and the ratio of cases with HLA-I homogeneity (K) or HLA LOH (L) among different primary localization using Fisher exact test; M-P, Comparative analysis of average MSI score (M), TMB (N), TNB (O), CD8⁺ TILs (P) among different primary localization using unpaired t-test with Welch’s correction. Data represent mean ± SEM. *P <.05, **P < .01.