Correlation of lung cancer mutational profile with immune profile.

Abstract

146 Background: The association between neoplasm mutational and immune profiles has not been well-characterized. Methods: We collected 26 lung cancer formalin-fixed paraffin embedded (FFPE) samples which had been tested with a comprehensive mutation profile to detect clinically actionable mutations, and a comprehensive immune gene expression profile, which interrogates PD-L1 immunohistochemistry (IHC), PD-L1/2 copy number, CD3/CD8 IHC, microsatellite instability status, mutational burden, and the expression profile of 54 immune-related genes. The ranking of gene expression and 7 immune phenotypes was compared to a reference population. Six cases were positive for an activating KRAS mutation and 2 cases were positive for an activating EGFR mutation. Principal component analysis was performed to determine the association of EGFR/KRAS mutations with the measured immune landscape. Results: The proinflammatory immune phenotype was significantly correlated with KRAS mutation positive samples (first principal component, R squared = 0.53, p < 0.05). Similarly, CD38 expression was correlated with KRAS mutation (R squared = 0.47, p < 0.05). CD137, KLRD1, and DDX58 expression was significantly correlated with EGFR positive samples (second principal component, R squared = 0.47, 0.37, 0.35 respectively, p < 0.05 in all cases). Unsupervised hierarchical clustering of the samples resulted in three distinct clusters, EGFR positive, KRAS positive, and EGFR negative/KRAS negative. In the KRAS positive cluster, high proinflammatory immune phenotype, VISTA moderate expression, presence of CD3/CD8 tumor infiltrating lymphocytes (TILs), and low KLRD1 were overrepresented (p < 0.05), while low VISTA and proinflammatory moderate immune phenotype were significantly underrepresented (p < 0.05). In the EGFR positive cluster DDX58 high, very low TILs, and very low CD8 were significantly (p < 0.05) overrepresented. Conclusions: KRAS mutation positivity is significantly associated with a proinflammatrory immune phenotype and CD3/CD8 infiltration. KRAS positive, EGFR positive, and KRAS/EGFR negative clusters are immunophenotypically distinct. A higher number of specimens is necessary to verify and expand these findings.