Genomic Variations and Immune-Related Features of TMB, PD-L1 Expression and CD8(+) T Cell Infiltration in Chinese Pulmonary Sarcomatoid Carcinoma

BACKGROUND: Pulmonary sarcomatoid carcinoma (PSC) is a rare and distinct subtype of lung cancer characterized by its aggressiveness and dismal prognosis. However, genomic landscape and immune contexture have not been fully elucidated among PSC patients. METHODS: In the present study, whole-exome-sequencing (WES) analyses were performed to depict genomic landscape of 38 independent PSC samples. Tumor mutation burden (TMB) was calculated with the total number of non-synonymous SNVs and indel variants per megabase of coding regions. PD-L1 expression and CD8(+) T cell density were evaluated by immunohistochemistry in PSC samples. Their associations with genomic mutation were further assessed in genes with most frequent mutation. Overall survival (OS) of PSC patients with top mutated genes and high and low TMB, PD-L1 and CD8(+) TIL expressions were further compared. Subgroup analyses of OS stratified by morphology and pathological type were conducted. Their correlation with TMB, PD-L1 and CD8(+) T cell were further assessed. RESULTS: We identified a cohort of genomic and somatic mutation in PSC patients. Subgroup patients with distinct clinicopathological features were found to harbor different genomic mutations and immunologic features. Besides, genomic profiles influenced outcomes, with SARS mutation associated with worsened prognosis. CONCLUSION: Through the mapping of genetic and immunologic landscape, we find the heterogeneity among the subgroups of PSC. Our findings may provide opportunities for therapeutic susceptibility among Chinese PSC patients.