Genomic profiles and their associations with TMB, PD-L1 expression, and immune cell infiltration landscapes in...

Diagnosing and treating patients with multiple primary lung cancers (MPLCs) bring challenges to the clinic, and the preliminary evidence has revealed unsatisfying outcomes after targeted therapy and immunotherapy. Therefore, we surveyed genomic profiles of MPLCs and their possible associations with tumor mutation burden (TMB), programmed death-ligand 1 (PD-L1), and the immune cell infiltration landscape.

A total of 112 patients with MPLCs with surgically resected 294 tumors were eligible, and 255 tumors were sequenced using a 1021-gene panel. Immunohistochemistry staining was performed to evaluate the levels of PD-L1 and the density of CD3+/CD8+ tumor-infiltrating lymphocytes (TILs), and CD68+/CD163+ tumor-associated macrophages (TAMs) at the central tumor and invasive margin, and immunotypes were generated based on those variables.

MPLCs often occur simultaneously in non-smoker women younger than 60 years and manifest as ground-glass opacities, adenocarcinoma, and stage I lung lesions. The most frequently mutated genes in the 255 tumors were EGFR (56%), ERBB2 (12%), TP53 (12%), BRAF (11%), RBM10 (11%), and KRAS (9%). We found 87 (77.7%) patients with diverse genomic profiles, and 61 (54.5%) who shared at least one putative driver gene between different tumors presented more aggressive tumors. The median TMB was 1.92 mutations/Mb, and high-TMB (≥3) lesions often harbored EGFR^L858R/KRAS^G12C/RBM10/TP53/LRP1B mutations or wild-type ERBB2. Only 8.1% of patients and 3.9% of lesions were positive for PD-L1 on tumor cells, and this positivity was more frequent in LRP1B/TP53-mutant tumors. EGFR^L858R/RBM10/TP53 mutations were positively associated with specific immune cells and an inflamed immunotype, but ERBB2 mutations were negatively correlated. TMB, CD3+TILs, and CD68+/CD163+ TAMs presented with significant heterogeneity among paired tumors (all kappa <0.2), but PD-L1 and CD8 +TILs were more uniformly present in tumor pairs.

MPLCs are driven by different molecular events and often exhibit low TMB, low PD-L1, and a heterogeneous immune infiltration landscape. Specific genomic profiles are associated with TMB and the tumor immune microenvironmental landscape in MPLCs. Our findings can help to guide MPLCs diagnoses and to identify patient populations that may benefit from immunotherapy and targeted therapy.